Lyn

Just one note - In the title you use the word "An" instead of the proper
word "A" - just something I noted (this type of error is common and usually
drives e crazy in my own writing!)

Ray




"Lyn J. Mangiameli" wrote in message
thlink.net...
The following is the near final draft of an article that will appear
with full formatting and photos in Fred Holder's periodical More
Woodturning. Part 2 by Joe Fleming will come out the following month.

Bowl Saving: An Comprehensive Discussion in Two Parts.

As the title indicates, this article will be composed of two parts. One
part will focus on a comparative discussion of the devices available to
obtain multiple bowls from one roughed out blank. The other part of the
article will focus on the techniques that help one most effectively use
these devices. To offer the most complete and comprehensive discussion,
Joe Fleming and I have teamed up for these articles. This offers the
opportunity to offer perspectives formed by different levels of
experience (Joe uses these devices more often than I do), different
exposure to the devices (I’ve have all of the devices, Joe is most
familiar with the Kelton), and different lathes (Joe uses the Stubby
lathe, while I use the Nova DVR).

Why Use a Bowl Coring Device?
So why bother to own a device that allows you to obtain more than one
bowl from a single blank? Clearly, the biggest issue is that it saves
wood, and even if you have a plentiful supply, there is some
satisfaction knowing that you have been able to use fully the material
available to you. When wood is unusually beautiful, expensive, or
uncommon (at least for you), the desire to obtain the maximal yield from
your supply is obvious. For some, the cost of wood includes chain and
chain saw expenses, fuel costs (both for the chain saw and to transport
both person and wood), sealers, and storage space, not to mention the
time involved obtaining the wood—so there is a lot of potential savings
from achieving maximal yield.

Most users find a coring device greatly speeds up the process of making
even one bowl. I don't think this is always the case, as it takes time
to mount, set up, then remove and stow most bowl saving systems, time
that could just be used to employ a gouge to remove the interior. But
for large bowls (say 16 inches or greater) or if considered over the
multiple bowls that are possible (i.e., production time per bowl), there
is almost always a significant time savings. Even for a recreational
woodturner, the combination of a savings in time and savings in cost is
apt to be meaningful.

There is also the issue of waste and its clean up. Obviously there will
be fewer shavings, which if you have some difficulty disposing of, can
be a big plus from using a bowl saver. Almost every turner soon learns
what a staggering amount of wood shavings and chips can be produced in
the making of a simple turning. There then becomes the problem of
getting them out of the way while turning, collecting them after the
session is over, and then somehow packaging them for final disposal.
Anything that reduces the amount of wood waste makes life a lot easier
for the turner. A bowl saver won’t eliminate waste, but it will
dramatically reduce the amount waste created for the amount of wood
initially mounted to the lathe.

And finally, apart from any monetary or material saving, some will find
it very nice to be able to make matched bowl sets of increasing size.
These nests of similar bowls have both aesthetic and financial appeal.

So the advantages of bowl savers are real, but does it still make sense
for the average woodturner to have one? Not necessarily, particularly if
one doesn’t make all that many bowls. I know of one turner who has an
expensive bowl saving system that he has used twice. He mostly makes
baseball bats and lamps. I think his purchase was more due to an
interest in the technology than a real need. Obviously that is OK, but
it does offer a good illustration of how one can purchase a very good
device, which in the end is not very useful given one's turning
preferences. The same thing can apply to people who primarily make
hollow forms, or for people who primarily make boxes, though for these
latter groups, the core can sometimes be use for a non-bowl turning like
a small hollow form.

There is also the issue of the size of the wood that is apt to be
obtainable (and/or affordable) and the size of the wood you can mount to
your lathe. You obviously don't need blades capable of removing a 18 or
20 inch bowl if you will never be able to mount wood over 16 inches on
your lathe. Nor will you need it if you are unlikely to have access to
wood over 18 inches in diameter (which by the time it is roughed down
isn't going to come in at much over 16 inches). So in such instances,
only a modest or perhaps no system at all is going to be quite
sufficient for one's needs.

The point I'm trying to make is that it is good to carefully think
through your present and future needs before purchasing a bowl saving
device. They are not an essential woodturning tool, even for those who
think of themselves as principally bowl turners, but if one does make a
lot of bowls, and takes the time to master the device, most won't ever
go back to the old methods. And for someone who sells their bowls, or
purchases expensive exotic woods, the cost of the system is apt to be
recouped in a very short time.

How Do They Work?
Specific techniques will be discussed in the second part, but here is a
very brief, generalized overview of their use. A bowl blank is
externally roughed out on the lathe and held in a chuck or with a
faceplate. Depending on choice of technique and bowl saving system, the
roughed out bowl blank may be held from either its base or the front
face, and with most systems the tailstock can be brought up for support.
Most bowl saving devices then require you to attach the device to the
lathe bed via a separate mounting plate and/or the banjo. The mount
holds a platform or gate which then supports and guides a blade into the
wood blank such that the blade separates an internal core from the outer
body (and hence the reason why bowl savers are sometimes called “coring
devices”). Often the blade (also referred to as a knife) is curved so
that when it is advanced through the wood, the resulting core resembles
a roughed out bowl (in some cases a straight blade can also be used
which results in a conical or funnel shaped core). This core may serve
as the blank for another smaller bowl. Oftentimes blades of different
size and radius can be used, or the same blade can be repositioned, in
such a way as to allow you to save multiple cores from a large blank.

Basically with all systems that use curved blades, you are making an
arcing cut into the bowl blank. Because of this, the final core size and
shape will be determined by four things: 1. the radius of the blade
itself (defining the shape of the arc); 2. where on the face of the
blank you begin your cut (determining the maximum diameter of the core);
3. the angle of entry (determining the depth of the arc, thus creating a
shallower or deeper core); and 4. the shape and size of the original
bowl blank (that restricts your freedom with respect to all of the
preceding decisions). For those that use a straight knife, the
determinants are really the same, except that the “radius” of the blade
and resulting cut is straight.

The Bowl Savers
There have been many bowl saving procedures developed over the years,
going back at least to pole lathe days using hooked tip tools. In more
recent times a number of home grown tools and methods have come into
being, including those described by the Lindquists, Ambrose and Leady.
Presently, there are four commercial bowl saving systems: The Stewart
Slicer; the Woodcut BowlSaver; the Kel McNaughton Centre-Saver System;
and the Oneway Easycore. Note that though there are four commercial
systems, there are many more packages. The Kelton has three; the
standard, the large, and the mini. Oneway has added two “mini” packages
of their own, as well as the array of posts and knives they offer as
part of their full size system. The Woodcut BowlSaver remains as a
single package. The original commercial system developed by Dennis
Stewart is composed of the Stewart Slicer and Armbrace, but is also
available in a virtually identical version manufactured by Sorby under
license from Stewart.

Though the tools all are capable of creating a core, I find there to be
a lot of differences between them, both in capability, technique and
overall ease of use. I have sometimes used one bowl saver to core the
small to medium range of bowls and another bowl saver system for the
largest outer bowls, though working with just one blank.

The Stewart Slicer was the original commercial coring system (likely
based loosely on the home made tool and techniques used by Melvin and
Mark Lindquist). Just a heavy duty straight tool mounted in the Stewart
armbrace, it offers an inexpensive way to core out bowls. The shaft is
of 3/4 inch round rod, that is tapered on its horizontal sides down to a
lightly fluted carbide tooth at the end. It is more wasteful of material
as the shaft is much thicker than the other systems’ blades and the
straight shape limits the shape of the bowl removed to more of a funnel
shape (which does happen to be a common and good aesthetic style for
bowls). Thus it is easy to have a round outer bowl and one or more
funnel shaped cores. If one already has an armbrace (be it Stewart,
Sorby or Pencil), it is a very inexpensive means to achieve occasional
cores, and it also works great as a heavy duty parting tool.

The Woodcut was one of the first single purpose dedicated coring systems
and it still has a lot going for it. It is very easy to use, very hard
to get in trouble with, and by using both a post and a tailstock mount,
is fairly stable on medium duty machines like the small Jets, Deltas and
Nova. The down side of this arrangement is that the tailstock cannot be
used to stabilize the bowl blank during coring. The sizes that the
Woodcut can core are well suited to the size bowls one can make on
lathes of 10 though 14 inch swing. However, being restricted to two
knives is obviously more limiting in the sizes and styles of bowls
obtainable compared to those systems that offer a wider variety of
blades. The Woodcut blades have Stellite tips that offer pretty good
life and can be replaced by sending the blade back to the manufacturer.
The package comes with a foam covered steel handle that will also make
for a comfortable handle for 1/2 inch diameter turning tools. It takes a
little longer to set up the Woodcut Bowl Saver than the Kelton or using
a Slicer, but the burden is not great. A video to assist with its use is
available, but I haven’t viewed it.

The Kel McNaughton Centre-Saver System (Kelton) is unique in two things,
one is its single tool gate mount via the banjo and the other is its
very wide range of knives, including straight as well as curved styles,
and both left and right handed blades that allow for the possibility of
inboard and outboard use. All of the blades are accommodated by the same
tool gate (though at present the mini blades require a spacer), which
serves to stabilize the tool against twist and to set the cutting edge
at the proper height. The main disadvantage of this arrangement, on
light to medium duty lathes is that their banjo may be too prone to
shifting position under the heavy horizontal loading passed along
through the gate. This can have disastrous results when using the Kelton
center saver; results which can include both bent knives and dismounted
bowls. This can be overcome by making up spacers to fit between the
headstock and the banjo. The spacers can be used to make for easy set up
for the proper depth of cut, and in the process deal with the shifting
of the banjo, but add to the bulk of any system (the idea comes from
Oneway and can be applied to the Kelton and Woodcut systems as well).
The up side of the banjo mounted gate, is that it is very easy and quick
to set up, or move from one lathe to another (as long as they both use
the same size tool post).

The Kelton is unmatched in the range of shapes and sizes of bowls that
can be made. It has more knives available and the knives can be easily
purchased individually from many sources. Thus you don't need to buy the
complete large set to obtain just the smallest of the large set knives.
Kelton alone has come out with a miniature set that allows for very
small cores to be removed. If one does small scale work and/or has
access to rare or expensive woods, this can be very appealing (it
certainly is to me). Many aren't aware of the small set, and Kelton has
just added a new even smaller knife. This small set presently requires a
gate spacer (provided by Kelton) to handle the smaller thinner knives,
but Kelton is considering modifying the standard gate in the near future
to take any of the sets (it will likely involve adding a new groove).
The packages usually include a Kelton steel handle that can be used with
your other turning tools. I like the Kelton versatility, but not its
relatively demanding requirement of precise technique. There are a lot
of written descriptions on its use (which don't always agree on
technique), but there is no good video to describe its use. Technique is
especially important in the larger sizes, where there is a lot of
overhang with no support. With good technique, all goes well, but with
poor technique it can be a miserable if not frightening experience.

The Oneway Easycore is an exceptionally complete, very rugged system
that is well mannered in use. The system is modular, to the extent that
you choose the bed locking plate, the mounting post height and the
specific blades that best match your lathe’s capabilities. Typical of
Oneway, it comes with all the wrenches needed for adjustment; it even
comes with a push tack to use to clear the Allen head bolts of any wood
debris buildup. Like with the other systems, the package includes one of
their Hosaluk style steel handles. It also comes with a good (not
excellent, but quite good) video describing its set up and operation.
The video is sufficiently detailed and helpful to be worth watching more
than once. The system is also much more expensive than the others, is
much bulkier to store and takes the longest time to set up (but only a
little longer).

The mounting system limits its use to lathes of 16 inch swing or larger
and is offered in separate versions for 16, 20, 24 and 26 inch swing
lathes. [Two smaller, more limited versions with only a single blade,
are available, for 10 inch and 12 inch swing lathes.] The mounting
system (what Oneway calls a “base unit”) is exceptionally solid. The
base is composed of two 1.75 inch OD posts, one thick flat mounting
plate, a bed locking plate (Oneway calls it a “clamp block”) and a large
locking bolt. The two posts are bolted to the flat plate and it is the
height of these posts that determines which of the different models will
match the swing of your lathe. Should one ever change to a lathe of
different swing, I see no reason why one shouldn't be able to just
purchase new posts of the correct height, for mounting to your existing
plate.

Oneway offers a nice selection of four curved blades and matching curved
toolrests for its original full sized system. Used together, the blades
allow conventionally shaped bowl cores to be removed in sizes from
approximately 10 inches to 18 inches in diameter. Some have reported
being able to remove cores as small as 5 inches with the smallest blade
in this system, but you won’t have a hemispherical shape. Of course
whether you can use the larger blade sizes will be dependent on the
swing of your lathe, but since the blades are purchased individually,
you can obtain only those applicable to your needs. Most will want the
first three sizes which is going to bring the cost of the system up to
almost $600 (and nearly $750 dollars with all four blades).

The blades are made from what looks to be stainless steel that has a
perpendicularly welded on post that fits in the base posts. The blade
pivots about this post. The blade on the Oneway system differs from all
the other coring systems in that is has an easily removable and
replaceable tip. Some of the many advantages to this system is greater
ease of sharpening, inexpensive replacement of worn tips, and the
ability to have extra tips of different cutting geometries. You can also
interchange tips between the various knives, which allows wear to be
spread across all of them (for the same number of bowls, the largest
blade will always have the most wear because it has the most material to
remove). The tip is made from CPM M-4, which is the same alloy steel
used in the Oneway (and some Glaser) gouges, and has fairly good, though
not outstanding edge retention. It cuts a path that is approximately 3/8
inch wide, which allows clearance for the 1/4 inch wide blades. Oneway
provides very complete directions for sharpening the tips both in print
(a copy comes with each blade and is also available on their web site)
and as a demonstration that is on the video that comes with the system.
Oneway describes use of a grinder, but I personally find them much
easier to sharpen using a vertical belt sander with a 120 or 150 grit
belt. I mount them to a small piece of square aluminum “rod” to make the
tip easier to hold (if for no other reason than heat).

To put the system to use, you must mount the base plate (with the
support posts already attached). Several methods can be used determine
the proper position, but I will leave that to the instructional video
and the second part of this article. Insert the blade you wish to use in
the blade support post (the midline post), and move the blade and base
to the position appropriate for the size core you wish to take. Clamp
the base plate to the bed firmly, now insert the tool rest in its
support post and make sure the blade will be just barely supported by
the toolrest. Fine height adjustments can be made by adjusting a bolt
that is fitted in the bottom of the blade and tool rest posts. In the
process of coring, you will swing the blade through an arc into the bowl
blank, pausing occasionally to clear chips and advance the curved tool
rest farther inwards to maintain support for the blade. It is this
continuous support, even when the blade is well advanced, that makes the
Easycore live up to its name.

So, if you’ve read this far, you probably won’t be surprised that I
don’t find any individual system to the undisputed choice for most
turners.

The Woodcut is likely the best choice for most with small and fairly
light duty lathes of 12-14 inch swing. The dual banjo and tailstock
mounting system provides an extra measure of stability for those lathes
with lighter duty banjos. The blades are well controlled and the system
easy to learn and operate, a big plus for those relatively new to
turning. The fact that the Woodcut offers two blade sizes and can be
used on a wide variety of lathe sizes (thus being transferable to future
lathe upgrade) likely gives it an advantage over the unreviewed Oneway
10 and 12 inch Easy Core systems. However, I can’t recommend the Woodcut
to those who already have larger lathes of 16 inch and up swing. Being
restricted to two blades is too limiting, and in the larger bowl sizes I
want my tailstock to be stabilizing the bowl blanks, not the bowl saver.
Still, if you make only a few bowls, want to turn them out in
traditional sizes, and want pure ease of use in an inexpensive package,
the Woodcut is actually a very appealing system.

The Kelton system is a classic, and has a long history of rave reviews.
If you want a lot of flexibility in shape and size (as small as 2 inch
with the mini blades), minimum bulk for storage off the lathe, the
ability to choose just the knives you want and need, have a stable banjo
(or are willing to help stabilize it with a spacer), are willing to be
attentive to developing and maintaining technique, and prize quick set
up and removal, the Kelton offers a great package at a price that is
moderate. However, the mount puts a lot of load on the lathe’s banjo and
for lathes like the Nova 3000 and DVR, the banjo locking mechanism is
only marginally stable enough for the task (of course this problem will
relate to the size of bowl being cored, being of no problem for small
cores). Even with a solid banjo, I just don’t believe the Kelton has the
best design for coring 16 inch or larger bowls, there is just too much
unsupported blade overhang. In the end, though, for most turners the
Kelton will offer the best balance between price, capability and
incremental expansion/upgradability.

The Oneway Easycore is an outstanding system, but at a price that will
make it unrealistic for some recreational woodturners. The Oneway offers
the greatest stability in its mount and provides unmatched support
during the largest and deepest of cuts, which makes it much safer, less
frustrating and less anxiety provoking to use. This comes at the price
of some limitation in shapes that can be achieved (there are no very
small knives and no straight blade), considerable expense, and a lot of
bulk. It will not do the very small bowls that the Kelton can (with the
appropriate knives), and does not offer the straight knives that can be
used for funnel shapes and as a heavy duty parting tool.

Finally, don’t count out the Stewart Slicer if you already have an
armbrace (be it Stewart, Sorby, or Pencil). It can be a bit scary to
use, but if you only rarely intend to core, don't need to achieve
maximal yield, have a use for a heavy duty parting tool (and most of us
do), and already have an armbrace, the Slicer will offer a lot of
capability for only $50.

In my opinion, if price were no object (which might be the case for the
professional turner as well as for the well heeled amateur), the best of
all possible worlds for the serious bowl turner would be to have BOTH
the Oneway Easy Core with #2, #3 and #4 inch blades, AND the Kelton
regular and mini packages. If one were to forego the #2 Oneway blade as
well, one can pretty much purchase the complete Kelton regular and
miniature packages for the cost of the #1 and #2 Oneway blades. The
Kelton shines at the smaller sizes, and indeed is the only system to
handle the smallest of sizes. It is also the only system, with its
straight blades, to offer maximal yield if your outer bowl is conical
rather than hemispherical in shape. On the other hand, the Oneway excels
in removal of large cores in excess of 13 inches, being both stable and
easy to operate.

Because I turn items in a wide range of sizes, it is this hybrid
combination that I find myself regularly using. If I’m working with
fairly small bowl blanks, I grab the Kelton because it is so quick to
set up and functions without incident for making smaller cores. However,
if I’m working with (what is for me) a large bowl blank that will
involve a core in the range of 13 to 15 inches (or more if I had a
larger lathe), I am happy to take the extra time to set up the Oneway to
achieve the relaxed uneventful core removal that follows. Even if you
have one or another complete system, I urge frequent bowl turners to
give thought to picking up a portion of one of the others.

Comparative Table:

Bowl Saver Blades Included Measured Blade Thickness Measured Tip
Thickness Replaceable Tip?
Kelton Mini 1 straight, two curved .20 .34 No
Kelton Regular 1 straight, three curved .23 .35 No
Kelton Large 1 straight, two curved .24 .38 No
Oneway Four curved .25 .35 User replaceable
Woodcut Two Curved .23 .33 Factory Replaceable
Stewart One straight . 15 up to .75 .17 No

Some Final Thoughts on Power:
One thing I chose not to touch on in the main review is the issue of
motor power. That is because I see motor power being an issue for all of
the coring devices. Based on my experience, motor power, as long at it
exceeds one horsepower, is definitely an issue, but does not preclude
use of any of the systems if one is willing to be patient. Power needs
are dependent on four things: the rate of entry of the knife (i.e.,
aggressiveness); friction secondary to side clearance (width of cut) and
shavings build up; diameter of the core being made, and density of the
wood. So, with lower horsepower lathes, you need to introduce the knives
slowly and gently, clear shavings often, make multiple cuts to increase
side clearance, limit your coring to smaller sizes (generally limited by
the swing of your lathe anyway) and stay away from dry exotic woods.
Doing those things, you can get by with a one horse power motor (using
your lowest speed pulley) and be fairly happy with a 1.5hp motor.
Ignoring those things, you can (and will) stall a 3 hp motor. Using my
DVR as an example, I have found it to have sufficient power to makes
cores of all sizes, in all woods, with all systems, without undue
stalling and fussiness.

The next part of the article will be by Joe Fleming and discuss both
basic and fine points in putting these systems to use.

Thanks, I caught it in the header but not the title (the mistake appears
in both areas in the WoodCentral version).

All in all, not as bad as the end of a recent Conservatorship report I
did where I wrote "And I testify under penalty of perjury that the
forging report is complete and accurate." Foregoing being the word
desired.

Lyn

Ray Sandusky wrote:

Lyn

Just one note - In the title you use the word "An" instead of the proper
word "A" - just something I noted (this type of error is common and usually
drives e crazy in my own writing!)

Ray




"Lyn J. Mangiameli" wrote in message
thlink.net...

The following is the near final draft of an article that will appear
with full formatting and photos in Fred Holder's periodical More
Woodturning. Part 2 by Joe Fleming will come out the following month.

Bowl Saving: An Comprehensive Discussion in Two Parts.

As the title indicates, this article will be composed of two parts. One
part will focus on a comparative discussion of the devices available to
obtain multiple bowls from one roughed out blank. The other part of the
article will focus on the techniques that help one most effectively use
these devices. To offer the most complete and comprehensive discussion,
Joe Fleming and I have teamed up for these articles. This offers the
opportunity to offer perspectives formed by different levels of
experience (Joe uses these devices more often than I do), different
exposure to the devices (I’ve have all of the devices, Joe is most
familiar with the Kelton), and different lathes (Joe uses the Stubby
lathe, while I use the Nova DVR).

Why Use a Bowl Coring Device?
So why bother to own a device that allows you to obtain more than one
bowl from a single blank? Clearly, the biggest issue is that it saves
wood, and even if you have a plentiful supply, there is some
satisfaction knowing that you have been able to use fully the material
available to you. When wood is unusually beautiful, expensive, or
uncommon (at least for you), the desire to obtain the maximal yield from
your supply is obvious. For some, the cost of wood includes chain and
chain saw expenses, fuel costs (both for the chain saw and to transport
both person and wood), sealers, and storage space, not to mention the
time involved obtaining the wood—so there is a lot of potential savings
from achieving maximal yield.

Most users find a coring device greatly speeds up the process of making
even one bowl. I don't think this is always the case, as it takes time
to mount, set up, then remove and stow most bowl saving systems, time
that could just be used to employ a gouge to remove the interior. But
for large bowls (say 16 inches or greater) or if considered over the
multiple bowls that are possible (i.e., production time per bowl), there
is almost always a significant time savings. Even for a recreational
woodturner, the combination of a savings in time and savings in cost is
apt to be meaningful.

There is also the issue of waste and its clean up. Obviously there will
be fewer shavings, which if you have some difficulty disposing of, can
be a big plus from using a bowl saver. Almost every turner soon learns
what a staggering amount of wood shavings and chips can be produced in
the making of a simple turning. There then becomes the problem of
getting them out of the way while turning, collecting them after the
session is over, and then somehow packaging them for final disposal.
Anything that reduces the amount of wood waste makes life a lot easier
for the turner. A bowl saver won’t eliminate waste, but it will
dramatically reduce the amount waste created for the amount of wood
initially mounted to the lathe.

And finally, apart from any monetary or material saving, some will find
it very nice to be able to make matched bowl sets of increasing size.
These nests of similar bowls have both aesthetic and financial appeal.

So the advantages of bowl savers are real, but does it still make sense
for the average woodturner to have one? Not necessarily, particularly if
one doesn’t make all that many bowls. I know of one turner who has an
expensive bowl saving system that he has used twice. He mostly makes
baseball bats and lamps. I think his purchase was more due to an
interest in the technology than a real need. Obviously that is OK, but
it does offer a good illustration of how one can purchase a very good
device, which in the end is not very useful given one's turning
preferences. The same thing can apply to people who primarily make
hollow forms, or for people who primarily make boxes, though for these
latter groups, the core can sometimes be use for a non-bowl turning like
a small hollow form.

There is also the issue of the size of the wood that is apt to be
obtainable (and/or affordable) and the size of the wood you can mount to
your lathe. You obviously don't need blades capable of removing a 18 or
20 inch bowl if you will never be able to mount wood over 16 inches on
your lathe. Nor will you need it if you are unlikely to have access to
wood over 18 inches in diameter (which by the time it is roughed down
isn't going to come in at much over 16 inches). So in such instances,
only a modest or perhaps no system at all is going to be quite
sufficient for one's needs.

The point I'm trying to make is that it is good to carefully think
through your present and future needs before purchasing a bowl saving
device. They are not an essential woodturning tool, even for those who
think of themselves as principally bowl turners, but if one does make a
lot of bowls, and takes the time to master the device, most won't ever
go back to the old methods. And for someone who sells their bowls, or
purchases expensive exotic woods, the cost of the system is apt to be
recouped in a very short time.

How Do They Work?
Specific techniques will be discussed in the second part, but here is a
very brief, generalized overview of their use. A bowl blank is
externally roughed out on the lathe and held in a chuck or with a
faceplate. Depending on choice of technique and bowl saving system, the
roughed out bowl blank may be held from either its base or the front
face, and with most systems the tailstock can be brought up for support.
Most bowl saving devices then require you to attach the device to the
lathe bed via a separate mounting plate and/or the banjo. The mount
holds a platform or gate which then supports and guides a blade into the
wood blank such that the blade separates an internal core from the outer
body (and hence the reason why bowl savers are sometimes called “coring
devices”). Often the blade (also referred to as a knife) is curved so
that when it is advanced through the wood, the resulting core resembles
a roughed out bowl (in some cases a straight blade can also be used
which results in a conical or funnel shaped core). This core may serve
as the blank for another smaller bowl. Oftentimes blades of different
size and radius can be used, or the same blade can be repositioned, in
such a way as to allow you to save multiple cores from a large blank.

Basically with all systems that use curved blades, you are making an
arcing cut into the bowl blank. Because of this, the final core size and
shape will be determined by four things: 1. the radius of the blade
itself (defining the shape of the arc); 2. where on the face of the
blank you begin your cut (determining the maximum diameter of the core);
3. the angle of entry (determining the depth of the arc, thus creating a
shallower or deeper core); and 4. the shape and size of the original
bowl blank (that restricts your freedom with respect to all of the
preceding decisions). For those that use a straight knife, the
determinants are really the same, except that the “radius” of the blade
and resulting cut is straight.

The Bowl Savers
There have been many bowl saving procedures developed over the years,
going back at least to pole lathe days using hooked tip tools. In more
recent times a number of home grown tools and methods have come into
being, including those described by the Lindquists, Ambrose and Leady.
Presently, there are four commercial bowl saving systems: The Stewart
Slicer; the Woodcut BowlSaver; the Kel McNaughton Centre-Saver System;
and the Oneway Easycore. Note that though there are four commercial
systems, there are many more packages. The Kelton has three; the
standard, the large, and the mini. Oneway has added two “mini” packages
of their own, as well as the array of posts and knives they offer as
part of their full size system. The Woodcut BowlSaver remains as a
single package. The original commercial system developed by Dennis
Stewart is composed of the Stewart Slicer and Armbrace, but is also
available in a virtually identical version manufactured by Sorby under
license from Stewart.

Though the tools all are capable of creating a core, I find there to be
a lot of differences between them, both in capability, technique and
overall ease of use. I have sometimes used one bowl saver to core the
small to medium range of bowls and another bowl saver system for the
largest outer bowls, though working with just one blank.

The Stewart Slicer was the original commercial coring system (likely
based loosely on the home made tool and techniques used by Melvin and
Mark Lindquist). Just a heavy duty straight tool mounted in the Stewart
armbrace, it offers an inexpensive way to core out bowls. The shaft is
of 3/4 inch round rod, that is tapered on its horizontal sides down to a
lightly fluted carbide tooth at the end. It is more wasteful of material
as the shaft is much thicker than the other systems’ blades and the
straight shape limits the shape of the bowl removed to more of a funnel
shape (which does happen to be a common and good aesthetic style for
bowls). Thus it is easy to have a round outer bowl and one or more
funnel shaped cores. If one already has an armbrace (be it Stewart,
Sorby or Pencil), it is a very inexpensive means to achieve occasional
cores, and it also works great as a heavy duty parting tool.

The Woodcut was one of the first single purpose dedicated coring systems
and it still has a lot going for it. It is very easy to use, very hard
to get in trouble with, and by using both a post and a tailstock mount,
is fairly stable on medium duty machines like the small Jets, Deltas and
Nova. The down side of this arrangement is that the tailstock cannot be
used to stabilize the bowl blank during coring. The sizes that the
Woodcut can core are well suited to the size bowls one can make on
lathes of 10 though 14 inch swing. However, being restricted to two
knives is obviously more limiting in the sizes and styles of bowls
obtainable compared to those systems that offer a wider variety of
blades. The Woodcut blades have Stellite tips that offer pretty good
life and can be replaced by sending the blade back to the manufacturer.
The package comes with a foam covered steel handle that will also make
for a comfortable handle for 1/2 inch diameter turning tools. It takes a
little longer to set up the Woodcut Bowl Saver than the Kelton or using
a Slicer, but the burden is not great. A video to assist with its use is
available, but I haven’t viewed it.

The Kel McNaughton Centre-Saver System (Kelton) is unique in two things,
one is its single tool gate mount via the banjo and the other is its
very wide range of knives, including straight as well as curved styles,
and both left and right handed blades that allow for the possibility of
inboard and outboard use. All of the blades are accommodated by the same
tool gate (though at present the mini blades require a spacer), which
serves to stabilize the tool against twist and to set the cutting edge
at the proper height. The main disadvantage of this arrangement, on
light to medium duty lathes is that their banjo may be too prone to
shifting position under the heavy horizontal loading passed along
through the gate. This can have disastrous results when using the Kelton
center saver; results which can include both bent knives and dismounted
bowls. This can be overcome by making up spacers to fit between the
headstock and the banjo. The spacers can be used to make for easy set up
for the proper depth of cut, and in the process deal with the shifting
of the banjo, but add to the bulk of any system (the idea comes from
Oneway and can be applied to the Kelton and Woodcut systems as well).
The up side of the banjo mounted gate, is that it is very easy and quick
to set up, or move from one lathe to another (as long as they both use
the same size tool post).

The Kelton is unmatched in the range of shapes and sizes of bowls that
can be made. It has more knives available and the knives can be easily
purchased individually from many sources. Thus you don't need to buy the
complete large set to obtain just the smallest of the large set knives.
Kelton alone has come out with a miniature set that allows for very
small cores to be removed. If one does small scale work and/or has
access to rare or expensive woods, this can be very appealing (it
certainly is to me). Many aren't aware of the small set, and Kelton has
just added a new even smaller knife. This small set presently requires a
gate spacer (provided by Kelton) to handle the smaller thinner knives,
but Kelton is considering modifying the standard gate in the near future
to take any of the sets (it will likely involve adding a new groove).
The packages usually include a Kelton steel handle that can be used with
your other turning tools. I like the Kelton versatility, but not its
relatively demanding requirement of precise technique. There are a lot
of written descriptions on its use (which don't always agree on
technique), but there is no good video to describe its use. Technique is
especially important in the larger sizes, where there is a lot of
overhang with no support. With good technique, all goes well, but with
poor technique it can be a miserable if not frightening experience.

The Oneway Easycore is an exceptionally complete, very rugged system
that is well mannered in use. The system is modular, to the extent that
you choose the bed locking plate, the mounting post height and the
specific blades that best match your lathe’s capabilities. Typical of
Oneway, it comes with all the wrenches needed for adjustment; it even
comes with a push tack to use to clear the Allen head bolts of any wood
debris buildup. Like with the other systems, the package includes one of
their Hosaluk style steel handles. It also comes with a good (not
excellent, but quite good) video describing its set up and operation.
The video is sufficiently detailed and helpful to be worth watching more
than once. The system is also much more expensive than the others, is
much bulkier to store and takes the longest time to set up (but only a
little longer).

The mounting system limits its use to lathes of 16 inch swing or larger
and is offered in separate versions for 16, 20, 24 and 26 inch swing
lathes. [Two smaller, more limited versions with only a single blade,
are available, for 10 inch and 12 inch swing lathes.] The mounting
system (what Oneway calls a “base unit”) is exceptionally solid. The
base is composed of two 1.75 inch OD posts, one thick flat mounting
plate, a bed locking plate (Oneway calls it a “clamp block”) and a large
locking bolt. The two posts are bolted to the flat plate and it is the
height of these posts that determines which of the different models will
match the swing of your lathe. Should one ever change to a lathe of
different swing, I see no reason why one shouldn't be able to just
purchase new posts of the correct height, for mounting to your existing
plate.

Oneway offers a nice selection of four curved blades and matching curved
toolrests for its original full sized system. Used together, the blades
allow conventionally shaped bowl cores to be removed in sizes from
approximately 10 inches to 18 inches in diameter. Some have reported
being able to remove cores as small as 5 inches with the smallest blade
in this system, but you won’t have a hemispherical shape. Of course
whether you can use the larger blade sizes will be dependent on the
swing of your lathe, but since the blades are purchased individually,
you can obtain only those applicable to your needs. Most will want the
first three sizes which is going to bring the cost of the system up to
almost $600 (and nearly $750 dollars with all four blades).

The blades are made from what looks to be stainless steel that has a
perpendicularly welded on post that fits in the base posts. The blade
pivots about this post. The blade on the Oneway system differs from all
the other coring systems in that is has an easily removable and
replaceable tip. Some of the many advantages to this system is greater
ease of sharpening, inexpensive replacement of worn tips, and the
ability to have extra tips of different cutting geometries. You can also
interchange tips between the various knives, which allows wear to be
spread across all of them (for the same number of bowls, the largest
blade will always have the most wear because it has the most material to
remove). The tip is made from CPM M-4, which is the same alloy steel
used in the Oneway (and some Glaser) gouges, and has fairly good, though
not outstanding edge retention. It cuts a path that is approximately 3/8
inch wide, which allows clearance for the 1/4 inch wide blades. Oneway
provides very complete directions for sharpening the tips both in print
(a copy comes with each blade and is also available on their web site)
and as a demonstration that is on the video that comes with the system.
Oneway describes use of a grinder, but I personally find them much
easier to sharpen using a vertical belt sander with a 120 or 150 grit
belt. I mount them to a small piece of square aluminum “rod” to make the
tip easier to hold (if for no other reason than heat).

To put the system to use, you must mount the base plate (with the
support posts already attached). Several methods can be used determine
the proper position, but I will leave that to the instructional video
and the second part of this article. Insert the blade you wish to use in
the blade support post (the midline post), and move the blade and base
to the position appropriate for the size core you wish to take. Clamp
the base plate to the bed firmly, now insert the tool rest in its
support post and make sure the blade will be just barely supported by
the toolrest. Fine height adjustments can be made by adjusting a bolt
that is fitted in the bottom of the blade and tool rest posts. In the
process of coring, you will swing the blade through an arc into the bowl
blank, pausing occasionally to clear chips and advance the curved tool
rest farther inwards to maintain support for the blade. It is this
continuous support, even when the blade is well advanced, that makes the
Easycore live up to its name.

So, if you’ve read this far, you probably won’t be surprised that I
don’t find any individual system to the undisputed choice for most

turners.

The Woodcut is likely the best choice for most with small and fairly
light duty lathes of 12-14 inch swing. The dual banjo and tailstock
mounting system provides an extra measure of stability for those lathes
with lighter duty banjos. The blades are well controlled and the system
easy to learn and operate, a big plus for those relatively new to
turning. The fact that the Woodcut offers two blade sizes and can be
used on a wide variety of lathe sizes (thus being transferable to future
lathe upgrade) likely gives it an advantage over the unreviewed Oneway
10 and 12 inch Easy Core systems. However, I can’t recommend the Woodcut
to those who already have larger lathes of 16 inch and up swing. Being
restricted to two blades is too limiting, and in the larger bowl sizes I
want my tailstock to be stabilizing the bowl blanks, not the bowl saver.
Still, if you make only a few bowls, want to turn them out in
traditional sizes, and want pure ease of use in an inexpensive package,
the Woodcut is actually a very appealing system.

The Kelton system is a classic, and has a long history of rave reviews.
If you want a lot of flexibility in shape and size (as small as 2 inch
with the mini blades), minimum bulk for storage off the lathe, the
ability to choose just the knives you want and need, have a stable banjo
(or are willing to help stabilize it with a spacer), are willing to be
attentive to developing and maintaining technique, and prize quick set
up and removal, the Kelton offers a great package at a price that is
moderate. However, the mount puts a lot of load on the lathe’s banjo and
for lathes like the Nova 3000 and DVR, the banjo locking mechanism is
only marginally stable enough for the task (of course this problem will
relate to the size of bowl being cored, being of no problem for small
cores). Even with a solid banjo, I just don’t believe the Kelton has the
best design for coring 16 inch or larger bowls, there is just too much
unsupported blade overhang. In the end, though, for most turners the
Kelton will offer the best balance between price, capability and
incremental expansion/upgradability.

The Oneway Easycore is an outstanding system, but at a price that will
make it unrealistic for some recreational woodturners. The Oneway offers
the greatest stability in its mount and provides unmatched support
during the largest and deepest of cuts, which makes it much safer, less
frustrating and less anxiety provoking to use. This comes at the price
of some limitation in shapes that can be achieved (there are no very
small knives and no straight blade), considerable expense, and a lot of
bulk. It will not do the very small bowls that the Kelton can (with the
appropriate knives), and does not offer the straight knives that can be
used for funnel shapes and as a heavy duty parting tool.

Finally, don’t count out the Stewart Slicer if you already have an
armbrace (be it Stewart, Sorby, or Pencil). It can be a bit scary to
use, but if you only rarely intend to core, don't need to achieve
maximal yield, have a use for a heavy duty parting tool (and most of us
do), and already have an armbrace, the Slicer will offer a lot of
capability for only $50.

In my opinion, if price were no object (which might be the case for the
professional turner as well as for the well heeled amateur), the best of
all possible worlds for the serious bowl turner would be to have BOTH
the Oneway Easy Core with #2, #3 and #4 inch blades, AND the Kelton
regular and mini packages. If one were to forego the #2 Oneway blade as
well, one can pretty much purchase the complete Kelton regular and
miniature packages for the cost of the #1 and #2 Oneway blades. The
Kelton shines at the smaller sizes, and indeed is the only system to
handle the smallest of sizes. It is also the only system, with its
straight blades, to offer maximal yield if your outer bowl is conical
rather than hemispherical in shape. On the other hand, the Oneway excels
in removal of large cores in excess of 13 inches, being both stable and
easy to operate.

Because I turn items in a wide range of sizes, it is this hybrid
combination that I find myself regularly using. If I’m working with
fairly small bowl blanks, I grab the Kelton because it is so quick to
set up and functions without incident for making smaller cores. However,
if I’m working with (what is for me) a large bowl blank that will
involve a core in the range of 13 to 15 inches (or more if I had a
larger lathe), I am happy to take the extra time to set up the Oneway to
achieve the relaxed uneventful core removal that follows. Even if you
have one or another complete system, I urge frequent bowl turners to
give thought to picking up a portion of one of the others.

Comparative Table:

Bowl Saver Blades Included Measured Blade Thickness Measured Tip
Thickness Replaceable Tip?
Kelton Mini 1 straight, two curved .20 .34 No
Kelton Regular 1 straight, three curved .23 .35 No
Kelton Large 1 straight, two curved .24 .38 No
Oneway Four curved .25 .35 User replaceable
Woodcut Two Curved .23 .33 Factory Replaceable
Stewart One straight . 15 up to .75 .17 No

Some Final Thoughts on Power:
One thing I chose not to touch on in the main review is the issue of
motor power. That is because I see motor power being an issue for all of
the coring devices. Based on my experience, motor power, as long at it
exceeds one horsepower, is definitely an issue, but does not preclude
use of any of the systems if one is willing to be patient. Power needs
are dependent on four things: the rate of entry of the knife (i.e.,
aggressiveness); friction secondary to side clearance (width of cut) and
shavings build up; diameter of the core being made, and density of the
wood. So, with lower horsepower lathes, you need to introduce the knives
slowly and gently, clear shavings often, make multiple cuts to increase
side clearance, limit your coring to smaller sizes (generally limited by
the swing of your lathe anyway) and stay away from dry exotic woods.
Doing those things, you can get by with a one horse power motor (using
your lowest speed pulley) and be fairly happy with a 1.5hp motor.
Ignoring those things, you can (and will) stall a 3 hp motor. Using my
DVR as an example, I have found it to have sufficient power to makes
cores of all sizes, in all woods, with all systems, without undue
stalling and fussiness.

The next part of the article will be by Joe Fleming and discuss both
basic and fine points in putting these systems to use.

Another excellent article Lyn. As I was reading it one thing that would
have been useful was a table...and you had that at the end. Still, there is
more info that could make the table a good reference. Stuff like lathe
swing range (10" min - 16"max), core sizes (xxx min, xxx max), retail price,
replaceable tip (Y, N), tip metal (M2, M4, etc).

I've been thinking about getting a corer, and this article really helped lay
out the different decision points.

Jeff Jilg
Austin, TX

Where was the article first posted?

Hi, Lyn! Can't recall if this has been raised with you before, but don't
you think it's time to consider burning a CD or two with all your articles
on it? I love the CD Steven produced and apparently a second one is in the
birthing process!

Leif
"Lyn J. Mangiameli" wrote in message
thlink.net...
The following is the near final draft of an article that will appear
with full formatting and photos in Fred Holder's periodical More
Woodturning. Part 2 by Joe Fleming will come out the following month.

Bowl Saving: An Comprehensive Discussion in Two Parts.

As the title indicates, this article will be composed of two parts. One
part will focus on a comparative discussion of the devices available to
obtain multiple bowls from one roughed out blank. The other part of the
article will focus on the techniques that help one most effectively use
these devices. To offer the most complete and comprehensive discussion,
Joe Fleming and I have teamed up for these articles. This offers the
opportunity to offer perspectives formed by different levels of
experience (Joe uses these devices more often than I do), different
exposure to the devices (I’ve have all of the devices, Joe is most
familiar with the Kelton), and different lathes (Joe uses the Stubby
lathe, while I use the Nova DVR).

Why Use a Bowl Coring Device?
So why bother to own a device that allows you to obtain more than one
bowl from a single blank? Clearly, the biggest issue is that it saves
wood, and even if you have a plentiful supply, there is some
satisfaction knowing that you have been able to use fully the material
available to you. When wood is unusually beautiful, expensive, or
uncommon (at least for you), the desire to obtain the maximal yield from
your supply is obvious. For some, the cost of wood includes chain and
chain saw expenses, fuel costs (both for the chain saw and to transport
both person and wood), sealers, and storage space, not to mention the
time involved obtaining the wood—so there is a lot of potential savings
from achieving maximal yield.

Most users find a coring device greatly speeds up the process of making
even one bowl. I don't think this is always the case, as it takes time
to mount, set up, then remove and stow most bowl saving systems, time
that could just be used to employ a gouge to remove the interior. But
for large bowls (say 16 inches or greater) or if considered over the
multiple bowls that are possible (i.e., production time per bowl), there
is almost always a significant time savings. Even for a recreational
woodturner, the combination of a savings in time and savings in cost is
apt to be meaningful.

There is also the issue of waste and its clean up. Obviously there will
be fewer shavings, which if you have some difficulty disposing of, can
be a big plus from using a bowl saver. Almost every turner soon learns
what a staggering amount of wood shavings and chips can be produced in
the making of a simple turning. There then becomes the problem of
getting them out of the way while turning, collecting them after the
session is over, and then somehow packaging them for final disposal.
Anything that reduces the amount of wood waste makes life a lot easier
for the turner. A bowl saver won’t eliminate waste, but it will
dramatically reduce the amount waste created for the amount of wood
initially mounted to the lathe.

And finally, apart from any monetary or material saving, some will find
it very nice to be able to make matched bowl sets of increasing size.
These nests of similar bowls have both aesthetic and financial appeal.

So the advantages of bowl savers are real, but does it still make sense
for the average woodturner to have one? Not necessarily, particularly if
one doesn’t make all that many bowls. I know of one turner who has an
expensive bowl saving system that he has used twice. He mostly makes
baseball bats and lamps. I think his purchase was more due to an
interest in the technology than a real need. Obviously that is OK, but
it does offer a good illustration of how one can purchase a very good
device, which in the end is not very useful given one's turning
preferences. The same thing can apply to people who primarily make
hollow forms, or for people who primarily make boxes, though for these
latter groups, the core can sometimes be use for a non-bowl turning like
a small hollow form.

There is also the issue of the size of the wood that is apt to be
obtainable (and/or affordable) and the size of the wood you can mount to
your lathe. You obviously don't need blades capable of removing a 18 or
20 inch bowl if you will never be able to mount wood over 16 inches on
your lathe. Nor will you need it if you are unlikely to have access to
wood over 18 inches in diameter (which by the time it is roughed down
isn't going to come in at much over 16 inches). So in such instances,
only a modest or perhaps no system at all is going to be quite
sufficient for one's needs.

The point I'm trying to make is that it is good to carefully think
through your present and future needs before purchasing a bowl saving
device. They are not an essential woodturning tool, even for those who
think of themselves as principally bowl turners, but if one does make a
lot of bowls, and takes the time to master the device, most won't ever
go back to the old methods. And for someone who sells their bowls, or
purchases expensive exotic woods, the cost of the system is apt to be
recouped in a very short time.

How Do They Work?
Specific techniques will be discussed in the second part, but here is a
very brief, generalized overview of their use. A bowl blank is
externally roughed out on the lathe and held in a chuck or with a
faceplate. Depending on choice of technique and bowl saving system, the
roughed out bowl blank may be held from either its base or the front
face, and with most systems the tailstock can be brought up for support.
Most bowl saving devices then require you to attach the device to the
lathe bed via a separate mounting plate and/or the banjo. The mount
holds a platform or gate which then supports and guides a blade into the
wood blank such that the blade separates an internal core from the outer
body (and hence the reason why bowl savers are sometimes called “coring
devices”). Often the blade (also referred to as a knife) is curved so
that when it is advanced through the wood, the resulting core resembles
a roughed out bowl (in some cases a straight blade can also be used
which results in a conical or funnel shaped core). This core may serve
as the blank for another smaller bowl. Oftentimes blades of different
size and radius can be used, or the same blade can be repositioned, in
such a way as to allow you to save multiple cores from a large blank.

Basically with all systems that use curved blades, you are making an
arcing cut into the bowl blank. Because of this, the final core size and
shape will be determined by four things: 1. the radius of the blade
itself (defining the shape of the arc); 2. where on the face of the
blank you begin your cut (determining the maximum diameter of the core);
3. the angle of entry (determining the depth of the arc, thus creating a
shallower or deeper core); and 4. the shape and size of the original
bowl blank (that restricts your freedom with respect to all of the
preceding decisions). For those that use a straight knife, the
determinants are really the same, except that the “radius” of the blade
and resulting cut is straight.

The Bowl Savers
There have been many bowl saving procedures developed over the years,
going back at least to pole lathe days using hooked tip tools. In more
recent times a number of home grown tools and methods have come into
being, including those described by the Lindquists, Ambrose and Leady.
Presently, there are four commercial bowl saving systems: The Stewart
Slicer; the Woodcut BowlSaver; the Kel McNaughton Centre-Saver System;
and the Oneway Easycore. Note that though there are four commercial
systems, there are many more packages. The Kelton has three; the
standard, the large, and the mini. Oneway has added two “mini” packages
of their own, as well as the array of posts and knives they offer as
part of their full size system. The Woodcut BowlSaver remains as a
single package. The original commercial system developed by Dennis
Stewart is composed of the Stewart Slicer and Armbrace, but is also
available in a virtually identical version manufactured by Sorby under
license from Stewart.

Though the tools all are capable of creating a core, I find there to be
a lot of differences between them, both in capability, technique and
overall ease of use. I have sometimes used one bowl saver to core the
small to medium range of bowls and another bowl saver system for the
largest outer bowls, though working with just one blank.

The Stewart Slicer was the original commercial coring system (likely
based loosely on the home made tool and techniques used by Melvin and
Mark Lindquist). Just a heavy duty straight tool mounted in the Stewart
armbrace, it offers an inexpensive way to core out bowls. The shaft is
of 3/4 inch round rod, that is tapered on its horizontal sides down to a
lightly fluted carbide tooth at the end. It is more wasteful of material
as the shaft is much thicker than the other systems’ blades and the
straight shape limits the shape of the bowl removed to more of a funnel
shape (which does happen to be a common and good aesthetic style for
bowls). Thus it is easy to have a round outer bowl and one or more
funnel shaped cores. If one already has an armbrace (be it Stewart,
Sorby or Pencil), it is a very inexpensive means to achieve occasional
cores, and it also works great as a heavy duty parting tool.

The Woodcut was one of the first single purpose dedicated coring systems
and it still has a lot going for it. It is very easy to use, very hard
to get in trouble with, and by using both a post and a tailstock mount,
is fairly stable on medium duty machines like the small Jets, Deltas and
Nova. The down side of this arrangement is that the tailstock cannot be
used to stabilize the bowl blank during coring. The sizes that the
Woodcut can core are well suited to the size bowls one can make on
lathes of 10 though 14 inch swing. However, being restricted to two
knives is obviously more limiting in the sizes and styles of bowls
obtainable compared to those systems that offer a wider variety of
blades. The Woodcut blades have Stellite tips that offer pretty good
life and can be replaced by sending the blade back to the manufacturer.
The package comes with a foam covered steel handle that will also make
for a comfortable handle for 1/2 inch diameter turning tools. It takes a
little longer to set up the Woodcut Bowl Saver than the Kelton or using
a Slicer, but the burden is not great. A video to assist with its use is
available, but I haven’t viewed it.

The Kel McNaughton Centre-Saver System (Kelton) is unique in two things,
one is its single tool gate mount via the banjo and the other is its
very wide range of knives, including straight as well as curved styles,
and both left and right handed blades that allow for the possibility of
inboard and outboard use. All of the blades are accommodated by the same
tool gate (though at present the mini blades require a spacer), which
serves to stabilize the tool against twist and to set the cutting edge
at the proper height. The main disadvantage of this arrangement, on
light to medium duty lathes is that their banjo may be too prone to
shifting position under the heavy horizontal loading passed along
through the gate. This can have disastrous results when using the Kelton
center saver; results which can include both bent knives and dismounted
bowls. This can be overcome by making up spacers to fit between the
headstock and the banjo. The spacers can be used to make for easy set up
for the proper depth of cut, and in the process deal with the shifting
of the banjo, but add to the bulk of any system (the idea comes from
Oneway and can be applied to the Kelton and Woodcut systems as well).
The up side of the banjo mounted gate, is that it is very easy and quick
to set up, or move from one lathe to another (as long as they both use
the same size tool post).

The Kelton is unmatched in the range of shapes and sizes of bowls that
can be made. It has more knives available and the knives can be easily
purchased individually from many sources. Thus you don't need to buy the
complete large set to obtain just the smallest of the large set knives.
Kelton alone has come out with a miniature set that allows for very
small cores to be removed. If one does small scale work and/or has
access to rare or expensive woods, this can be very appealing (it
certainly is to me). Many aren't aware of the small set, and Kelton has
just added a new even smaller knife. This small set presently requires a
gate spacer (provided by Kelton) to handle the smaller thinner knives,
but Kelton is considering modifying the standard gate in the near future
to take any of the sets (it will likely involve adding a new groove).
The packages usually include a Kelton steel handle that can be used with
your other turning tools. I like the Kelton versatility, but not its
relatively demanding requirement of precise technique. There are a lot
of written descriptions on its use (which don't always agree on
technique), but there is no good video to describe its use. Technique is
especially important in the larger sizes, where there is a lot of
overhang with no support. With good technique, all goes well, but with
poor technique it can be a miserable if not frightening experience.

The Oneway Easycore is an exceptionally complete, very rugged system
that is well mannered in use. The system is modular, to the extent that
you choose the bed locking plate, the mounting post height and the
specific blades that best match your lathe’s capabilities. Typical of
Oneway, it comes with all the wrenches needed for adjustment; it even
comes with a push tack to use to clear the Allen head bolts of any wood
debris buildup. Like with the other systems, the package includes one of
their Hosaluk style steel handles. It also comes with a good (not
excellent, but quite good) video describing its set up and operation.
The video is sufficiently detailed and helpful to be worth watching more
than once. The system is also much more expensive than the others, is
much bulkier to store and takes the longest time to set up (but only a
little longer).

The mounting system limits its use to lathes of 16 inch swing or larger
and is offered in separate versions for 16, 20, 24 and 26 inch swing
lathes. [Two smaller, more limited versions with only a single blade,
are available, for 10 inch and 12 inch swing lathes.] The mounting
system (what Oneway calls a “base unit”) is exceptionally solid. The
base is composed of two 1.75 inch OD posts, one thick flat mounting
plate, a bed locking plate (Oneway calls it a “clamp block”) and a large
locking bolt. The two posts are bolted to the flat plate and it is the
height of these posts that determines which of the different models will
match the swing of your lathe. Should one ever change to a lathe of
different swing, I see no reason why one shouldn't be able to just
purchase new posts of the correct height, for mounting to your existing
plate.

Oneway offers a nice selection of four curved blades and matching curved
toolrests for its original full sized system. Used together, the blades
allow conventionally shaped bowl cores to be removed in sizes from
approximately 10 inches to 18 inches in diameter. Some have reported
being able to remove cores as small as 5 inches with the smallest blade
in this system, but you won’t have a hemispherical shape. Of course
whether you can use the larger blade sizes will be dependent on the
swing of your lathe, but since the blades are purchased individually,
you can obtain only those applicable to your needs. Most will want the
first three sizes which is going to bring the cost of the system up to
almost $600 (and nearly $750 dollars with all four blades).

The blades are made from what looks to be stainless steel that has a
perpendicularly welded on post that fits in the base posts. The blade
pivots about this post. The blade on the Oneway system differs from all
the other coring systems in that is has an easily removable and
replaceable tip. Some of the many advantages to this system is greater
ease of sharpening, inexpensive replacement of worn tips, and the
ability to have extra tips of different cutting geometries. You can also
interchange tips between the various knives, which allows wear to be
spread across all of them (for the same number of bowls, the largest
blade will always have the most wear because it has the most material to
remove). The tip is made from CPM M-4, which is the same alloy steel
used in the Oneway (and some Glaser) gouges, and has fairly good, though
not outstanding edge retention. It cuts a path that is approximately 3/8
inch wide, which allows clearance for the 1/4 inch wide blades. Oneway
provides very complete directions for sharpening the tips both in print
(a copy comes with each blade and is also available on their web site)
and as a demonstration that is on the video that comes with the system.
Oneway describes use of a grinder, but I personally find them much
easier to sharpen using a vertical belt sander with a 120 or 150 grit
belt. I mount them to a small piece of square aluminum “rod” to make the
tip easier to hold (if for no other reason than heat).

To put the system to use, you must mount the base plate (with the
support posts already attached). Several methods can be used determine
the proper position, but I will leave that to the instructional video
and the second part of this article. Insert the blade you wish to use in
the blade support post (the midline post), and move the blade and base
to the position appropriate for the size core you wish to take. Clamp
the base plate to the bed firmly, now insert the tool rest in its
support post and make sure the blade will be just barely supported by
the toolrest. Fine height adjustments can be made by adjusting a bolt
that is fitted in the bottom of the blade and tool rest posts. In the
process of coring, you will swing the blade through an arc into the bowl
blank, pausing occasionally to clear chips and advance the curved tool
rest farther inwards to maintain support for the blade. It is this
continuous support, even when the blade is well advanced, that makes the
Easycore live up to its name.

So, if you’ve read this far, you probably won’t be surprised that I
don’t find any individual system to the undisputed choice for most
turners.

The Woodcut is likely the best choice for most with small and fairly
light duty lathes of 12-14 inch swing. The dual banjo and tailstock
mounting system provides an extra measure of stability for those lathes
with lighter duty banjos. The blades are well controlled and the system
easy to learn and operate, a big plus for those relatively new to
turning. The fact that the Woodcut offers two blade sizes and can be
used on a wide variety of lathe sizes (thus being transferable to future
lathe upgrade) likely gives it an advantage over the unreviewed Oneway
10 and 12 inch Easy Core systems. However, I can’t recommend the Woodcut
to those who already have larger lathes of 16 inch and up swing. Being
restricted to two blades is too limiting, and in the larger bowl sizes I
want my tailstock to be stabilizing the bowl blanks, not the bowl saver.
Still, if you make only a few bowls, want to turn them out in
traditional sizes, and want pure ease of use in an inexpensive package,
the Woodcut is actually a very appealing system.

The Kelton system is a classic, and has a long history of rave reviews.
If you want a lot of flexibility in shape and size (as small as 2 inch
with the mini blades), minimum bulk for storage off the lathe, the
ability to choose just the knives you want and need, have a stable banjo
(or are willing to help stabilize it with a spacer), are willing to be
attentive to developing and maintaining technique, and prize quick set
up and removal, the Kelton offers a great package at a price that is
moderate. However, the mount puts a lot of load on the lathe’s banjo and
for lathes like the Nova 3000 and DVR, the banjo locking mechanism is
only marginally stable enough for the task (of course this problem will
relate to the size of bowl being cored, being of no problem for small
cores). Even with a solid banjo, I just don’t believe the Kelton has the
best design for coring 16 inch or larger bowls, there is just too much
unsupported blade overhang. In the end, though, for most turners the
Kelton will offer the best balance between price, capability and
incremental expansion/upgradability.

The Oneway Easycore is an outstanding system, but at a price that will
make it unrealistic for some recreational woodturners. The Oneway offers
the greatest stability in its mount and provides unmatched support
during the largest and deepest of cuts, which makes it much safer, less
frustrating and less anxiety provoking to use. This comes at the price
of some limitation in shapes that can be achieved (there are no very
small knives and no straight blade), considerable expense, and a lot of
bulk. It will not do the very small bowls that the Kelton can (with the
appropriate knives), and does not offer the straight knives that can be
used for funnel shapes and as a heavy duty parting tool.

Finally, don’t count out the Stewart Slicer if you already have an
armbrace (be it Stewart, Sorby, or Pencil). It can be a bit scary to
use, but if you only rarely intend to core, don't need to achieve
maximal yield, have a use for a heavy duty parting tool (and most of us
do), and already have an armbrace, the Slicer will offer a lot of
capability for only $50.

In my opinion, if price were no object (which might be the case for the
professional turner as well as for the well heeled amateur), the best of
all possible worlds for the serious bowl turner would be to have BOTH
the Oneway Easy Core with #2, #3 and #4 inch blades, AND the Kelton
regular and mini packages. If one were to forego the #2 Oneway blade as
well, one can pretty much purchase the complete Kelton regular and
miniature packages for the cost of the #1 and #2 Oneway blades. The
Kelton shines at the smaller sizes, and indeed is the only system to
handle the smallest of sizes. It is also the only system, with its
straight blades, to offer maximal yield if your outer bowl is conical
rather than hemispherical in shape. On the other hand, the Oneway excels
in removal of large cores in excess of 13 inches, being both stable and
easy to operate.

Because I turn items in a wide range of sizes, it is this hybrid
combination that I find myself regularly using. If I’m working with
fairly small bowl blanks, I grab the Kelton because it is so quick to
set up and functions without incident for making smaller cores. However,
if I’m working with (what is for me) a large bowl blank that will
involve a core in the range of 13 to 15 inches (or more if I had a
larger lathe), I am happy to take the extra time to set up the Oneway to
achieve the relaxed uneventful core removal that follows. Even if you
have one or another complete system, I urge frequent bowl turners to
give thought to picking up a portion of one of the others.

Comparative Table:

Bowl Saver Blades Included Measured Blade Thickness Measured Tip
Thickness Replaceable Tip?
Kelton Mini 1 straight, two curved .20 .34 No
Kelton Regular 1 straight, three curved .23 .35 No
Kelton Large 1 straight, two curved .24 .38 No
Oneway Four curved .25 .35 User replaceable
Woodcut Two Curved .23 .33 Factory Replaceable
Stewart One straight . 15 up to .75 .17 No

Some Final Thoughts on Power:
One thing I chose not to touch on in the main review is the issue of
motor power. That is because I see motor power being an issue for all of
the coring devices. Based on my experience, motor power, as long at it
exceeds one horsepower, is definitely an issue, but does not preclude
use of any of the systems if one is willing to be patient. Power needs
are dependent on four things: the rate of entry of the knife (i.e.,
aggressiveness); friction secondary to side clearance (width of cut) and
shavings build up; diameter of the core being made, and density of the
wood. So, with lower horsepower lathes, you need to introduce the knives
slowly and gently, clear shavings often, make multiple cuts to increase
side clearance, limit your coring to smaller sizes (generally limited by
the swing of your lathe anyway) and stay away from dry exotic woods.
Doing those things, you can get by with a one horse power motor (using
your lowest speed pulley) and be fairly happy with a 1.5hp motor.
Ignoring those things, you can (and will) stall a 3 hp motor. Using my
DVR as an example, I have found it to have sufficient power to makes
cores of all sizes, in all woods, with all systems, without undue
stalling and fussiness.

The next part of the article will be by Joe Fleming and discuss both
basic and fine points in putting these systems to use.

Hi Jeff,
I agree I like the quick accessiblility of information available in a
table.

I had intended to discuss core sizes, then decided against it. Core
diameter is determined not just by knife, but by the depth you can/wish
to work with, your intended yield and stylistic issues. Thus I'm not
certain it is actually that informative to talk of sizes of pure
hemispherical cores, particularly when the Kelton and Slicer can produce
conical cores.

Minimum swing is a limiting issue on only the Oneway, which is described
in the text.

Even retail prices are problematic as the Kelton and Oneway are
available in so many different configurations.

I did list whether the tip was replaceable in the table, but this
information was likely hard to decipher as my formatted Word tables
become gobbledygook when the hit the text only NG.

Tip metal is described in the text for the Slicer (carbide), Woodcut
(Stellite), and Oneway (M4), but the Kelton tip is integral to the shaft
and to my knoweldge the tool steel used remains proprietary information.

I do appreciate the comments and will see if I can work some of your
suggestions into the final table.

Lyn

Jeff Jilg wrote:
Another excellent article Lyn. As I was reading it one thing that would
have been useful was a table...and you had that at the end. Still, there is
more info that could make the table a good reference. Stuff like lathe
swing range (10" min - 16"max), core sizes (xxx min, xxx max), retail price,
replaceable tip (Y, N), tip metal (M2, M4, etc).

I've been thinking about getting a corer, and this article really helped lay
out the different decision points.

Jeff Jilg
Austin, TX

Hi Leif,
This came up a few months ago and I have given it some thought. From my
side of things, I try to provide information that might have some
reference value, but at the same time I recognize that much of what I
write about is constantly changing and evolving. Most articles I have
written have been revised and updated at least once, and usually more
than once. That is the rub. I don't have the energy to put up my own
website (where it would be easy to keep the current versions available),
in the end I'm skittish about turning them over to someone else's
website (though I have received some very generous offers), I don't want
to compete with Fred Holder's back issue sales, and a CD would burn in
plastic words that might change two weeks later. For example, my buffing
article has been updated four times, and is about to be completely
overhauled to incorporate some new products. So I'd feel strange about
someone having paid for a CD, then having the article they paid for not
contain the current information.

I am open for suggestions and possibly even joint ventures. I'm not
really interested in making any money, but I must admit I would like to
have some of these articles be more readily available as a resource and
reference, particularly in a way that could include the photos and
diagrams and formatted tables that I am not able to offer at the
newsgroup level, and are only viewable in gray scale in More Woodturning.

Lyn

Leif Thorvaldson wrote:

Hi, Lyn! Can't recall if this has been raised with you before, but don't
you think it's time to consider burning a CD or two with all your articles
on it? I love the CD Steven produced and apparently a second one is in the
birthing process!

Leif

Hello Mike,

I can verify that there is indeed a left handed set of Kelton knives for the
Centre Saver, as I have two sets. They work as you mentioned, cutting from
the headstock to the tailstock end.

They can also be used on the large outboard side of the Oneway (and other
lathes) for reverse coring. In fact, I use them often in this manner. Take
care and all the best to you and yours!
--
Better Woodturning and Finishing Through Chemistry...

"Woodturning with Steven D. Russell" CD now available!
More than 93,000 words, and 500+ photos in 21 articles, email for details.

Steven D. Russell
Eurowood Werks Woodturning Studio
The Woodlands, Texas

Machinery, Tool and Product Testing for
the Woodturning and Woodworking Industries
"Mike Paulson" wrote in message
...
Hi Lyn,

Nice article, as usual. Perhaps you will talk about this in the second
part, but I believe it is worth a mention in the categories of saving wood
and lessening shavings - using the coring tools to rough shape the
exterior of the largest bowl. You basically part off a ring of wood from
the outside. I have heard of some people who save these to make mirror
frames, but I just do it to help reduce the shavings pile. I have a
standard McNaughton which I must use from the tailstock end, so that means
mounting the blank on a faceplate with the bottom of the future bowl
towards the headstock. I have heard but not verified that there is / was
a reverse curve McNaughton blade that would allow you to make this cut
from the headstock end while the blank was mounted between centers.
Actually, I am more likely to pick up my Stewart Slicer to make this cut
during initial roughing out with the blank between centers, cutting from
the side first, and then coming straight in from the bottom to meet the
original cut and part off the ring. This has the advantage of being
easier to remove the ring - loosen the tailstock as opposed to unscrewing
the faceplate with blank attached - and I prefer to rough out the external
bowl shape at this stage rather than after the blank has been mounted on
the faceplate or chuck.

-mike paulson, fort collins, co

"Lyn J. Mangiameli" wrote in message rthlink.net...
The following is the near final draft of an article that will appear
with full formatting and photos in Fred Holder's periodical More
Woodturning. Part 2 by Joe Fleming will come out the following month.
go back to the old methods.................

Lyn!
It has been some time since I looked at this news group. What a good
description of the subject!Absolutely perfect from what I know about
the subject.
I do not have a coring system but if I decide to buy one in the future
this sure will help me make a choice much easier
Would it be possible to post it on WoW in the "Filing Cabinet"
perhaps?
maybe Herm does not know you wrote this article.
There will be many family Members interested in this one.
Thank you very much
Eugen Schlaak