Hi Barry. Just read your post but see it was written a week ago. Have
you had success since then? Here's a situation where instruction from a
professional turner would be valuable. An expert would see the cause of
the problem at a glance and help you overcome it easily. In lieu of that,
here are some things to consider:

When you say ripples, do you mean chatter marks versus ridges that are
even all the way around the bowl, or do you mean shiny rings that are
basically flush with the surface, or do you mean rings of torn grain? If
you are getting chatter, it can come from either the tool flexing or the
wood bouncing against the tool. Is your lathe heavy enough? Does it
vibrate as you turn? Is your bowl supported adequately? Bring up the
tailstock and see if that helps. If it does, then your headstock or
bearings or chuck/faceplate may be the problem. A 6" bowl should be well
within the capabilities of even a small lathe.

Ripples in the traditional meaning of the term (shallow ridges) often come
from less than perfect tool control. Are you moving the tool with body
motion (good) or hand and arm motion? Is the tool held firmly against the
tool rest? Ripples usually sand out easily. Is your sandpaper fresh and
sharp? Are you using a coarse grit to start? Is your wood too wet to
sand easily? Is a wet slurry clogging your sandpaper? Are you sanding
with the grain or against the grain?

If the grain is torn, are you cutting from base to rim on the outside of
the bowl (with the grain) or from rim to base (against the grain). Is
your tool angle 45 degrees or more (the part of the cutting edge touching
the wood, not the tool shaft/handle angle)? Are you using the best tool
for the finishing cut? A small gouge with a thin bevel (not so small that
it chatters) will make a cleaner cut than a bigger tool or coarser bevel.

Shiny rings are caused by too much bevel pressure and can be difficult to
sand out. Rubbing the bevel is a bit of a misnomer. Touch the bevel
lightly against the wood, as close to zero pressure as possible. Keep
pressure against the tool rest but don't put pressure against the wood.

If your ridges are truly too deep to sand out easily, they can be levelled
with shear scraping. Scraping with the tool flat on the tool rest usually
causes some tear out. Hold a freshly sharpened scraper so that the part
of the metal touching the wood is at 45 degrees (like a clock hand
pointing at 10:30), moving the tool from base to rim. Use a light touch
against the wood. Stop and resharpen every 5 seconds when shear scraping.

Let me know if any of this helps.

-mike paulson, fort collins, co

------

On Tue Sep 14, 2004, "Barry N. Turner" wrote:

I am turning a bowl (about 6" in diameter by about 6" deep, side grain)
from green Black Walnut. I have shaped the exterior of the bowl. When I
started to power sand, I noticed that the outside of the bowl had several
concentric ripples. These ripples are a bit too deep to remove by power
sanding, but have eluded removal with a bowl gouge or scraper. I have not
hollowed the bowl yet, so it shouldn't be moving too much.

I have tried taking a very fine cut with a sharp bowl gouge, but the new
surface had just as many ripples. What is going on here? I'm pretty new
to green wood turning. Do I just need to rough the bowl and let it dry
for a couple of weeks before I proceed? Any suggestions will be much
appreciated. Thanks.

Barry

It was the chuck. I started with my Supernova chuck, but turned the foot
too small and switched to my Nova Compac chuck. The Compac chuck just
didn't grip tight enough and the blank was moving slightly with every
revolution of the lathe when I tried to make a cut. I reversed the blank
back onto the Supernova and brought the tailstock up. Problem solved!
Thanks for helping me figure it out. I'm usually able to figure things
like
this out myself, but for some reason, this one eluded me.

Barry

"Mike Paulson" wrote in message
...
Hi Barry. Just read your post but see it was written a week ago. Have
you had success since then? Here's a situation where instruction from a
professional turner would be valuable. An expert would see the cause of
the problem at a glance and help you overcome it easily. In lieu of that,
here are some things to consider:

When you say ripples, do you mean chatter marks versus ridges that are
even all the way around the bowl, or do you mean shiny rings that are
basically flush with the surface, or do you mean rings of torn grain? If
you are getting chatter, it can come from either the tool flexing or the
wood bouncing against the tool. Is your lathe heavy enough? Does it
vibrate as you turn? Is your bowl supported adequately? Bring up the
tailstock and see if that helps. If it does, then your headstock or
bearings or chuck/faceplate may be the problem. A 6" bowl should be well
within the capabilities of even a small lathe.

Ripples in the traditional meaning of the term (shallow ridges) often come
from less than perfect tool control. Are you moving the tool with body
motion (good) or hand and arm motion? Is the tool held firmly against the
tool rest? Ripples usually sand out easily. Is your sandpaper fresh and
sharp? Are you using a coarse grit to start? Is your wood too wet to
sand easily? Is a wet slurry clogging your sandpaper? Are you sanding
with the grain or against the grain?

If the grain is torn, are you cutting from base to rim on the outside of
the bowl (with the grain) or from rim to base (against the grain). Is
your tool angle 45 degrees or more (the part of the cutting edge touching
the wood, not the tool shaft/handle angle)? Are you using the best tool
for the finishing cut? A small gouge with a thin bevel (not so small that
it chatters) will make a cleaner cut than a bigger tool or coarser bevel.

Shiny rings are caused by too much bevel pressure and can be difficult to
sand out. Rubbing the bevel is a bit of a misnomer. Touch the bevel
lightly against the wood, as close to zero pressure as possible. Keep
pressure against the tool rest but don't put pressure against the wood.

If your ridges are truly too deep to sand out easily, they can be levelled
with shear scraping. Scraping with the tool flat on the tool rest usually
causes some tear out. Hold a freshly sharpened scraper so that the part
of the metal touching the wood is at 45 degrees (like a clock hand
pointing at 10:30), moving the tool from base to rim. Use a light touch
against the wood. Stop and resharpen every 5 seconds when shear scraping.

Let me know if any of this helps.

-mike paulson, fort collins, co

------

On Tue Sep 14, 2004, "Barry N. Turner" wrote:

I am turning a bowl (about 6" in diameter by about 6" deep, side grain)
from green Black Walnut. I have shaped the exterior of the bowl. When I
started to power sand, I noticed that the outside of the bowl had several
concentric ripples. These ripples are a bit too deep to remove by power
sanding, but have eluded removal with a bowl gouge or scraper. I have not
hollowed the bowl yet, so it shouldn't be moving too much.

I have tried taking a very fine cut with a sharp bowl gouge, but the new
surface had just as many ripples. What is going on here? I'm pretty new
to green wood turning. Do I just need to rough the bowl and let it dry
for a couple of weeks before I proceed? Any suggestions will be much
appreciated. Thanks.

Barry