Does anybody have a good method for finishing off the bottoms of bowls.
Kevin

Hi Kevin

I do have an album that shows the end results of finishing my
bowls/patters, etc

However the way to get there is not always the same, depending on size
and shape, and on whatever you have on "tools" to do the finishing, by"
tools" I mean chucks like donut chucks, or jam chucks or cole jaws etc.
here's the address to the bowl bottom album

http://homepage.mac.com/l.vanderloo/PhotoAlbum23.html

Have fun and take care
Leo Van Der Loo

Kevin
I have three basic ways to finish off a bowl bottom.
1) jam chucking
2) working the bottom against a sanding pad held in the lathe
3) using home-made large jaws (see the web site)
in the past I have also used a compression or dough-nut chuck.

--
God bless and safe turning
Darrell Feltmate
Truro, NS Canada
www.aroundthewoods.com

"Kevin Cleary" wrote in message
news:IdPJf.707$KZ1.142@trndny09...
Does anybody have a good method for finishing off the bottoms of bowls.
Kevin


What are you after? You trying to make them ornate or presentable?

Presentable is easy. You just set up the bottom prior to reversing on a
chuck to hollow .

http://photobucket.com/albums/d160/G...t=278f0535.jpg
For a strictly inside hold.

http://photobucket.com/albums/d160/G...t=bb09ce26.jpg
Which allows hold inside or out. All that's required prior to finish is a
brief cleanup of chuck artifact, which you can see in the bottom of the
recess.

If you want to do more elaborate versions, you'll need to reverse after
hollowing and hold by one of the many methods others recommend. I'd favor
a Longworth for ease of use, though I paid for the Cole jaws, and use them
when I need them. http://www.glassgiant.com/misc/longworth_chuck/

Kevin Cleary wrote:
Does anybody have a good method for finishing off the bottoms of bowls.

No one so far has mentioned vacuum chucking which is another option to
consider, though it is expensive and I have yet to bite the bullet

If you want to reverse turn, the technique you use depends on the rim
design. For example, a bowl with a natural edge cannot be held with
anything that grips around the rim. A bowl with an in-turning rim
generally cannot be held in a standard cole jaw. I have made special
grippers for one of my popular bowl designs, but it's a lot of work for
a one-off.

try some of these google searches:

doughnut chuck

longworth chuck

vacuum chuck

cole jaws

--
Derek Andrews, woodturner

http://www.seafoamwoodturning.com
http://chipshop.blogspot.com - a blog for my customers
http://www.seafoamwoodturning.com/TheToolrest/ - a blog for woodturners

I don't like cole jaws and such because... Even when the blank is dry,
the rim is never going to be 100% because of the release of tension in
the blank as wood is removed. All of the bowl is going to move but the
rim will move the most -- I suspect that one cannot find any bowl which
would stand up to flat and completely round rim as measured by a good
method.

That said, the best way of driving a reversed blank (IMHO) is jam chuck
it with a chuck made so that the driving force is applied pretty close
to the bottom of the bowl.

Assuming that you have a 4 jaw chuck... To make a cheap jam chuck, get a
piece of schedule 40 pvc joint (the thing you use to glue two pieces of
pipe together) which will cost you well under a dollar I think.

Expand into one end of it to hold it and true up the free end. Scrape
unless you want some nasty catches.

Now reverse it and true up the other end.

Here I make a half round indentation into the end and glue in a piece of
1/4" diameter buna cord -- Packard sells it for about $10.00/5'.

Another approach which I have not tried but I bet will work is to round
over the free end and coat it with a silicone material -- some of the
gasket-making stuff you can get in a small tube at the auto parts store.

Another, even less costly approach, is to cover the end with several
layers of duct tape.

Then, you are done.

To use it, jam the reversed bowl between the chuck and the tailstock.
You can add a piece of paper towel to keep the gasket material from
marking your bowl. You can take the center pin out of the live center
so as not to mark the bottom too deeply or you can use a home-made
something which covers the tailstock pins.

Now you can detail the bottom except for a small section which you can't
get to right in the middle. You do that by hand.

Now, I usually use vacuum chucking and I have just described to you how
my vacuum chuck was made, almost. The only change to the above was a
method for keeping the vacuum in spite of a 4 jaw chuck being pretty
leaky! That is for another day.

Bill

Derek Andrews wrote:
Kevin Cleary wrote:

Does anybody have a good method for finishing off the bottoms of bowls.


No one so far has mentioned vacuum chucking which is another option to
consider, though it is expensive and I have yet to bite the bullet

If you want to reverse turn, the technique you use depends on the rim
design. For example, a bowl with a natural edge cannot be held with
anything that grips around the rim. A bowl with an in-turning rim
generally cannot be held in a standard cole jaw. I have made special
grippers for one of my popular bowl designs, but it's a lot of work for
a one-off.

try some of these google searches:

doughnut chuck

longworth chuck

vacuum chuck

cole jaws

Derek Andrews wrote:
Kevin Cleary wrote:

Does anybody have a good method for finishing off the bottoms of bowls.


No one so far has mentioned vacuum chucking which is another option to
consider, though it is expensive and I have yet to bite the bullet

If you want to reverse turn, the technique you use depends on the rim
design. For example, a bowl with a natural edge cannot be held with
anything that grips around the rim. A bowl with an in-turning rim
generally cannot be held in a standard cole jaw. I have made special
grippers for one of my popular bowl designs, but it's a lot of work for
a one-off.

try some of these google searches:

doughnut chuck

longworth chuck

vacuum chuck

cole jaws

Derek, Why can't you hold a bowl with an in-turning rim on cole jaws? I
place the grips on the inside of the rim and it works fine. I can't
tighten it to much on thin walled bowls, but it doesn't have to be to
tight just to finish the bottom.

Bill Rubenstein wrote:
I don't like cole jaws and such because... Even when the blank is dry,
the rim is never going to be 100% because of the release of tension in
the blank as wood is removed.

Unless you are looking for an absolutely concentric fixing, which
generally isn't necessary, I can't say I have ever found rim distortion
to be a real problem when using cole jaws.


That said, the best way of driving a reversed blank (IMHO) is jam chuck
it with a chuck made so that the driving force is applied pretty close
to the bottom of the bowl.

I'm gonna be pedantic about semantics here, and say that what you
describe is not a jam chuck, or at least it is contrary to my
understanding of the term.

I have always considered a jam chuck to be a piece of scrap wood turned
to exactly the right size such that a small bowl (or box etc) can be
jammed onto it and held securely in place without tailstock support. The
jam chuck may grip either inside or outside the turning. If the fit is a
little sloppy, a paper towel may be used between the jam chuck and the
turning.



--
Derek Andrews, woodturner

http://www.seafoamwoodturning.com
http://chipshop.blogspot.com - a blog for my customers
http://www.seafoamwoodturning.com/TheToolrest/ - a blog for woodturners

Derek Andrews wrote:
Ralph wrote:

Derek, Why can't you hold a bowl with an in-turning rim on cole jaws?


Sorry. I was only thinking of one specific case, and then generalised.

What I should have said was that cole jaws do not suit all rim designs.
With the buttons supplied with cole jaws you need to be able to grip the
rim at its highest point (relative to the base), or very close to it. If
that high spot isn't on the inside or outside edge of the rim, there is
nothing there to grip, at least with the cole jaw buttons supplied.

An example is this bowl:
http://www.seafoamwoodturning.com/Shopping/BB_bowl.htm

I have wooden extenders that I fit to the cole jaws. They fit around the
outside of the bowl and grip it very securely so I can turn at
reasonable speed while having full access to the bottom of the bowl.


Gotcha.

For me, most of my bottoms are a mortice (recess) which is sanded and
that is my finished bottom. This is the easiest for me.

While mounted, you can use a parting tool to part of the mortice, then
sand out the marks. This will also work for a tenon.

You can sand the bottom, and then apply a waste block using hot melt
glue (see Darrell's site), wood glue and paper or super glue, and waste
block with mortice or tenon, and after turning the inside. The waste
block parts off easily with a chisel and there is minimal cleanup.

If you don't have a chuck, and use a face plate, you just part it off
the lathe and sand it out.

Belt sanders can be used to clean up the bottoms of bowls.

You can also make a disc sander that fits on your lathe for sanding the
bottom of your bowls.

I use the angle drills for sanding out the mortices on my bowls. I have
1, 2, and 3 inch discs, which covers all of the mortice sizes that I
use.

robo hippy

Hi Derek

The vacuum chuck was covered by the etc., G I do have the setup but
don't use it very much.
You have the same problems with the vacuum as you have with any setup,
chuck etc, like holes and warping and size, especially small and
warped, as the surface area is small and the holding per square area,
1kg per cm2 or 15lbs per inch2 does not add up to much.
As for cost it does not have to be that high, a good little compressor
or vacuum pump does not have to cost very much,(Bill Noble has always
had some nice pumps for sale and also some of the accessories etc) and
the hardware if you don't have any lying around should not add up much
either, the vacuum chucks you can easily turn yourself.
I do use the jumbo jaws on my Oneway stronghold a lot, and with the 8
buttons very often there are only 4 holding because of the warping of
the bowl/platter shape, but you would be surpriced to see how close one
can get the turning to center, by pushing and shifting while tightening
up.
Then some tape wrapped around or as some use the plastic klingwrap you
can get a good hold on a piece, but again as you also know there are
limits to shape and size you can hold.
Couple of pics. in this album show my vacuum setup, it's just visual
though.

http://homepage.mac.com/l.vanderloo/PhotoAlbum25.html

Have fun and take care
Leo Van Der Loo

Ok, let's not call what I described a jam chuck -- let's call it
something which works well for me and for everybody who has copied this
design (such as it is) and is CHEAP.

My feeling is that the system I use works in all cases where cole jaws
will work also. But, cole jaws will not work in all cases where my
system works -- natural edge bowls, for instance. So, storage space and
money being limited quantities, why should I have both?

Bill

Derek Andrews wrote:
Bill Rubenstein wrote:

I don't like cole jaws and such because... Even when the blank is
dry, the rim is never going to be 100% because of the release of
tension in the blank as wood is removed.


Unless you are looking for an absolutely concentric fixing, which
generally isn't necessary, I can't say I have ever found rim distortion
to be a real problem when using cole jaws.


That said, the best way of driving a reversed blank (IMHO) is jam
chuck it with a chuck made so that the driving force is applied pretty
close to the bottom of the bowl.


I'm gonna be pedantic about semantics here, and say that what you
describe is not a jam chuck, or at least it is contrary to my
understanding of the term.

I have always considered a jam chuck to be a piece of scrap wood turned
to exactly the right size such that a small bowl (or box etc) can be
jammed onto it and held securely in place without tailstock support. The
jam chuck may grip either inside or outside the turning. If the fit is a
little sloppy, a paper towel may be used between the jam chuck and the
turning.

Hi Bill

I think I would call your jam chuck a friction drive, and maybe that's
not the right name either, but it is cheap and readily made, and
probably used by almost every turner in one way or another, be it just
a chunk of wood or in some more elaborate dimension.
The question why should I have both, well to take just my case and this
also would be so for everyone who moves the headstock to the end of
their lathe and also if a swung headstock is used, we are not able to
use the tail stock to steady the turning.
I do use the Mega jumbo jaws a lot, they are very quickly put on and
very flexible, from 5" to 15" by just moving the rubber bumpers, and if
larger is needed I have 4 1/4 pies that I will bolt on and the bumpers
are then screwed into those pies, I have used them for larger than 20",
and yes I am very careful when working with those large sizes.
Yes I do want both, friction drive and jumbo jaws.

http://homepage.mac.com/l.vanderloo/PhotoAlbum25.html

Have fun and take care
Leo Van Der Loo

I want to thank everyone for their inpuy.I'm going to experiment ansd see
what works best for me.
Kevin
"Kevin Cleary" wrote in message
news:IdPJf.707$KZ1.142@trndny09...
Does anybody have a good method for finishing off the bottoms of bowls.
Kevin

On Sun, 19 Feb 2006 13:48:43 GMT, Derek Andrews
wrote:

No one so far has mentioned vacuum chucking which is another option to
consider, though it is expensive and I have yet to bite the bullet

It's really not that expensive if you buy used parts, Derek..
I'm in the process of setting mine up now... main parts were from Bill Noble for
less that $200... I figure that if I didn't already have plumbing fittings and
stuff, that's another $20 to $40 including a couple of sealed bearings..


Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm

On Mon, 20 Feb 2006 01:39:15 GMT, Bill Rubenstein wrote:

Ok, let's not call what I described a jam chuck -- let's call it
something which works well for me and for everybody who has copied this
design (such as it is) and is CHEAP.

My feeling is that the system I use works in all cases where cole jaws
will work also. But, cole jaws will not work in all cases where my
system works -- natural edge bowls, for instance. So, storage space and
money being limited quantities, why should I have both?

Bill

I use the Oneway version of the cole jaws, (jumbo), and they have slots in
addition to the holes...
That solves the problem of oval warped bowls, but still doesn't address the
warped rim...
If it doesn't sit flat on a table when you put it rim down, you won't be happy
with the jumbo/cole jaws, either...


Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm

On 19 Feb 2006 12:23:43 -0800, "robo hippy" wrote:


You can also make a disc sander that fits on your lathe for sanding the
bottom of your bowls.


Good point, Reed...

I can't remember if I posted pictures last year, but I made a very reliable
setup by turning a tenon for the chuck on a scrap of plywood, reversing it and
turning it round, flush and 3" in diameter...
I used spray adhesive to put 3" discs on, since I always have them handy...


Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm

here is a cheap way that I have used to turn the bottom of my bowls
(natural edge) I usually have a tenon on the bottom and mark the center
with the skew I have a piece of 3/4 inch ply 9 inch round mounted on
the chuck I then put the bowl in a small rubber ball and place it up
against the flat surface of the ply in the chuck, bring up the tail and
center into the bowl bottom apply pressure to the ball turn by hand to
get to turn round and take off the bottom as far as I can reach. The
rest ( about the size of a pencil) I sand off by hand and finish. Speed
is important and getting the bowl to turn round is good but I have done
this many times with good success. Gordon