Keith Young wrote:
I,ve been turning bowls now for a few years off and on. One thing that
bothers me is that every now and then after i finish one i notice that i
didn,t turn the bottom flat ( if that was my purpose.) Its only after the
finish is applied that this becomes obvious.Any suggestions.

If you mean that you FORGOT to turn the bottom before you finished the
bowl, I would suggest laying off the booze until you have finished in
the workshop

If you mean that what appeared flat when it was on the lathe, but looks
rippled when it is polished, then I can sympathise with that. I recently
turned a very shallow artsy piece which is basically a platter. I
thought it was flat across the 'platter' surface, but a few coats of
danish and a good buffing prooved otherwise. Flat surfaces are tricky.

More care and attention is needed. Maybe offer up a straight edge. Maybe
polish it with fine abrasive and shine a light across the 'flat'.

I am guessing though that your problem is the base that the bowl sits
on. I think the best solution is to dish it out somewhat, or decorate it
by some means. I don't find totally flat bases aesthetically pleasing.


--
Derek Andrews, woodturner

http://www.seafoamwoodturning.com
Wedding Favors ~ Artisan Crafted Gifts ~ One-of-a-Kind Woodturning

Large flat surfaces such as on flat platters or plates are a challenge
without a doubt. I use a straightedge but that won't necessarily catch the
very small waviness that shows up when finished. You can try shining a light
on the surface at a shallow angle and your sense of touch can be a help. If
you can feel it you can see it - note these are also drywall sanding
techniques as well.

I find that power sanding is better than hand sanding. If you are also
referring to the bump that appears in the center of bowl bottoms, I find
power sanding to be a great help since there is sandpaper "movement"
produced by the turning disk. When you hand sand in the center there is very
little movement since the workpiece radius is very small which means you
remove less material at the absolute center and increasingly more as the
radius increases for a given application of the paper.
Billh

"Keith Young" wrote in message
...
Hi

I,ve been turning bowls now for a few years off and on. One thing that
bothers me is that every now and then after i finish one i notice that i
didn,t turn the bottom flat ( if that was my purpose.) Its only after the
finish is applied that this becomes obvious.Any suggestions.

Keith

Wood moves and if you don't allow for it you are saking for trouble. A flat bottom is a no-
no. The piece should sit on a foot which is distinct and the rest of the bottom should be
concave so as to clear the table or whatever.

Now, that will almost get you there. Even if the wood is perfectly dry when you finish the
bottom, because you are removing wood which may relieve stresses in the wood which is left,
you need to take one additional step. Make yourself a sanding block maybe 6" x 6" and glue
some 220 or so to it. After the piece has aired for a little while (maybe the next day) rub
the bottom on the sanding block to re-flatten it.

Then if it moves, you have done all that you can do...

Bill

In article ,
says...
Keith Young wrote:
I,ve been turning bowls now for a few years off and on. One thing that
bothers me is that every now and then after i finish one i notice that i
didn,t turn the bottom flat ( if that was my purpose.) Its only after the
finish is applied that this becomes obvious.Any suggestions.

If you mean that you FORGOT to turn the bottom before you finished the
bowl, I would suggest laying off the booze until you have finished in
the workshop

If you mean that what appeared flat when it was on the lathe, but looks
rippled when it is polished, then I can sympathise with that. I recently
turned a very shallow artsy piece which is basically a platter. I
thought it was flat across the 'platter' surface, but a few coats of
danish and a good buffing prooved otherwise. Flat surfaces are tricky.

More care and attention is needed. Maybe offer up a straight edge. Maybe
polish it with fine abrasive and shine a light across the 'flat'.

I am guessing though that your problem is the base that the bowl sits
on. I think the best solution is to dish it out somewhat, or decorate it
by some means. I don't find totally flat bases aesthetically pleasing.

What Bill said, except that you may have any bottom contour you like, not
necessarily what most call a "foot." As long as you begin with a
relieved -concave- area at the bottom, you can wait a week or so and either
drag it over paper or run the block over it. I keep some stickyback paper
adhered to a tabletop to get a flat seat for bowls turned green to finish
contour.

If you're having these problems with bowls you think were dry, have a bit
of patience and dry them longer. Unless you've got some truly thin bottoms,
the wood will adjust along the lines of least resistance as you scoop it
out - the thin end grain above.

"Bill Rubenstein" wrote in message
. net...
Wood moves and if you don't allow for it you are saking for trouble. A
flat bottom is a no-
no. The piece should sit on a foot which is distinct and the rest of the
bottom should be
concave so as to clear the table or whatever.

Now, that will almost get you there. Even if the wood is perfectly dry
when you finish the
bottom, because you are removing wood which may relieve stresses in the
wood which is left,
you need to take one additional step. Make yourself a sanding block maybe
6" x 6" and glue
some 220 or so to it. After the piece has aired for a little while (maybe
the next day) rub
the bottom on the sanding block to re-flatten it.


Keith Young wrote:
I,ve been turning bowls now for a few years off and on. One thing
that
bothers me is that every now and then after i finish one i notice that
i
didn,t turn the bottom flat ( if that was my purpose.) Its only after
the
finish is applied that this becomes obvious.Any suggestions.

On Sat, 6 Nov 2004 09:21:38 -0330, "Keith Young"
wrote:

Derek
No not the base that it sits on. That I concave in slightly. The interior
of the bowl i,m refering too. I don,t like all my bowls that concave in (
on the inside ) but some that seem perfectly flat when i,m finished are not
when the finish is applied.maybe a flat edged plastic ruler would give me a
good indication before i decide there finished.

Keith

when I visualize trying to get a bowl (what size are we talking
about?) totally flat inside, I wonder how you are doing the
transition from bottom to side. That is particularly hard to sand. If
a bowl is wide enough, then yes, a small straight edge could help, but
if you look in your cupboard at the various metal, ceramic and pottery
bowls, you won't find many with a 'flat' bottom because even a small
curve makes them easier to work with.

If you are determined to achieve a certain 'look', just make several
wooden blocks of various widths that you can use as small
straightedges,,,

"Bill Day" wrote in message
...
On Sat, 6 Nov 2004 09:21:38 -0330, "Keith Young"
wrote:
SNIP ...
when I visualize trying to get a bowl (what size are we talking
about?) totally flat inside, I wonder how you are doing the
transition from bottom to side. That is particularly hard to sand. If
a bowl is wide enough, then yes, a small straight edge could help, but
if you look in your cupboard at the various metal, ceramic and pottery
bowls, you won't find many with a 'flat' bottom because even a small
curve makes them easier to work with.

If you are determined to achieve a certain 'look', just make several
wooden blocks of various widths that you can use as small
straightedges,,,
===========================
If you do the above and put some adhesive back sand paper on each one, it
will help achieve that flat you're looking for.

Ken Moon
Webberville, TX

Keith,

I believe I would be trying for a curved inside bottom, rather than one that
is tabletop flat. Curves are inherently more pleasing to the eye. Of
course, not all curves are pleasing. It takes some work to get just the
right curve. Flats simply are.......well, boring.

Also, as you have discovered, absolutely flat surfaces are very hard to come
by in woodturning. I vote for curves!

Just think how unappealing the "other gender" would look if composed
entirely of straight lines!

Barry


"Keith Young" wrote in message
...
Derek
No not the base that it sits on. That I concave in slightly. The interior
of the bowl i,m refering too. I don,t like all my bowls that concave in (
on the inside ) but some that seem perfectly flat when i,m finished are
not
when the finish is applied.maybe a flat edged plastic ruler would give me
a
good indication before i decide there finished.

Keith


"Derek Andrews" wrote in message
...
Keith Young wrote:
I,ve been turning bowls now for a few years off and on. One thing that
bothers me is that every now and then after i finish one i notice that
i
didn,t turn the bottom flat ( if that was my purpose.) Its only after
the
finish is applied that this becomes obvious.Any suggestions.

If you mean that you FORGOT to turn the bottom before you finished the
bowl, I would suggest laying off the booze until you have finished in
the
workshop

If you mean that what appeared flat when it was on the lathe, but looks
rippled when it is polished, then I can sympathise with that. I recently
turned a very shallow artsy piece which is basically a platter. I
thought
it was flat across the 'platter' surface, but a few coats of danish and
a
good buffing prooved otherwise. Flat surfaces are tricky.

More care and attention is needed. Maybe offer up a straight edge. Maybe
polish it with fine abrasive and shine a light across the 'flat'.

I am guessing though that your problem is the base that the bowl sits
on.
I think the best solution is to dish it out somewhat, or decorate it by
some means. I don't find totally flat bases aesthetically pleasing.


--
Derek Andrews, woodturner

http://www.seafoamwoodturning.com
Wedding Favors ~ Artisan Crafted Gifts ~ One-of-a-Kind Woodturning

The most recent issue of Woodturning Design has an article on getting a
perfectly flat surface on a platter. After using a straight edge to get it
as flat as possible, the author power sands. Before he sands though, he
makes some radial pencil lines and gives a quick sanding, this will show the
slight ripple remaining. I don't have the article with me, so I might not
have it 100% right.
Martin

"billh" wrote in message
...
Large flat surfaces such as on flat platters or plates are a challenge
without a doubt. I use a straightedge but that won't necessarily catch the
very small waviness that shows up when finished. You can try shining a
light
on the surface at a shallow angle and your sense of touch can be a help.
If
you can feel it you can see it - note these are also drywall sanding
techniques as well.

I find that power sanding is better than hand sanding. If you are also
referring to the bump that appears in the center of bowl bottoms, I find
power sanding to be a great help since there is sandpaper "movement"
produced by the turning disk. When you hand sand in the center there is
very
little movement since the workpiece radius is very small which means you
remove less material at the absolute center and increasingly more as the
radius increases for a given application of the paper.
Billh

"Keith Young" wrote in message
...
Hi

I,ve been turning bowls now for a few years off and on. One thing that
bothers me is that every now and then after i finish one i notice that i
didn,t turn the bottom flat ( if that was my purpose.) Its only after
the
finish is applied that this becomes obvious.Any suggestions.

Keith