Need help learning to build the bottom of a segmented bowl

msgJohn

New Member
when i try to create a bottom ring using segments, i wind of with gaps between the segments. This happens as i get closer to the center of the bowl bottom. Is there a video showing the correct way to do this or how to fix it.
 

mfisher

Super Moderator
Staff member
Hi John.

I don't know of links to videos that covers what you are wanting to explain.
Creating a base out of segments for a base is challenging as you have discovered. Part of the problem is the thinness of the wood at the point. When gluing it can cause the wood swell and possible warp.
- Do a dry fit at see how well the disk is formed.
- Don't glue the tip end of the segment. You can come back later at glue with thin CA
- You could try making half circles and then sand the joining edges to make a clean tight fit circle.

If the base in less than four inches, consider using a thin solid base.
 

Mike Mitchell

PRO Member
Hi John.

I don't know of links to videos that covers what you are wanting to explain.
Creating a base out of segments for a base is challenging as you have discovered. Part of the problem is the thinness of the wood at the point. When gluing it can cause the wood swell and possible warp.
- Do a dry fit at see how well the disk is formed.
- Don't glue the tip end of the segment. You can come back later at glue with thin CA
- You could try making half circles and then sand the joining edges to make a clean tight fit circle.

If the base in less than four inches, consider using a thin solid base.
Could I chime in here with a question for mfisher?????
I have heard people say to use a floating bottom, as if for some reason there is a chance for the bottom to change dimensions in different weather and cause a crack. Is that anything to worry about? I don't know how they make their floating bottoms.
 

mfisher

Super Moderator
Staff member
Could I chime in here with a question for mfisher?????
I have heard people say to use a floating bottom, as if for some reason there is a chance for the bottom to change dimensions in different weather and cause a crack. Is that anything to worry about? I don't know how they make their floating bottoms.

Depends on the size of your bottom. I have made numerous turnings with a solid base which are over 11 years old. None of them have cracked. Some of them were gifts and resides in a different humidity area in the US.

Some have said a good rule is if the base is 4" or less you most likely will not have a problem.

Attached are two articles . 1 covering base basics and the second one on floating bases.

=============
Forgot to mention from your first post.
My comment on gluing is when dealing with a large number of segments per ring. (like 36 segments in a 4" or less diameter ring.)
the issue is the wood is paper thin near the center of the circle/ring. The glue swells the wood.

Some have build half rings and then sand the two halves for a good fit.
 

Attachments

  • BASE-ics.pdf
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  • floating_base.pdf
    1.4 MB · Views: 31
I did segmented bottoms when I started, but rarely do them anymore. I use a solid bottom unless the dimension is 6" or more. Then I might do a segmented bottom, but only six segments (which works fine even on a bowl with 12, 24 or 36 segments per ring). If you really want to do a segmented bottom with more than 6 segments you have to glue the segments together in pairs first, clamping both the top and bottom because the wet glue tends to curl the thinner top of the wedge (as another person responded). Then glue the pairs together until you have two halves. Sand the two halves where they will meet (carefully to avoid distorting the center), and then glue the halves together. Even then, I have had cracks develop over time as the wood moves. I decided it wasn't worth the hassle.
 

Mark Inmon

PRO Member
Mr Kevin Neelley has a good writeup on this in the segmented woodturners user group with very detailed photos of the process.
 

Lloyd Johnson

Administrator
Staff member
when i try to create a bottom ring using segments, i wind of with gaps between the segments. This happens as i get closer to the center of the bowl bottom. Is there a video showing the correct way to do this or how to fix it.
If there are ever gaps between the segments, it means that your cutting angle is not correct. If the gaps are towards the inside of the ring, it means that your cutting angle is greater than the target angle and less than the target angle if the gaps are on the outside.

If you’re using a wedgie sled to cut your segments that has a perfectly-angled wedge to align the fences, the culprit is likely that one or both of your fences has long edges that are not parallel. It could also mean that the board from which you are cutting the segments does not have parallel long edges. Finally, make sure you mark one side of the board and that the marked side is ALWAYS facing up and that the mark on each segment is facing up when you glue the ring. Practically every cutting sled has an angle that is not perfect. If all segments have the mark on the side facing up, the error will be zeroed out and the ring will have no gaps. If the segments aren’t facing correctly, there will likely be gaps.

Lloyd
 
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