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Segmented Bowl Question

H

Howard Beaver

Joined
Feb 22, 2007
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Location
Paddock Lake, WI
This is my first post on the forum, however I have lurking for quite a while.

I've just been bitten by the segmented bug, and bitten hard. One thing I have noticed in all the vast number of segmented bowls I have turned - 3, there is some fine tear out on each segment just prior to the next segment the tool touches. As the tool cuts the next segment initially it's smooth then progresses to the fine tear out again. Any suggestions?


Howard Beaver
 
Try shorter segments (more segments per ring), you'll see that it won't happen any more (or not as much).

The grain at the joints ends are very short and do not have enough wood to support itself.
 
Howard, normally, the "tear out" problem would be at the beginning of each segment, because that's where you would be cutting into the angular end grain of the segment; so I'm not sure why you would be having this problem on the out-going side of the cut. Ron's suggestion to build your ring with more segments will definitely help reduce tear-out. I occasionally construct rings with less than 16 segments, but 16 has become my norm.
 
I used to experience that problem so I simply tried different tools and cutting techniques. Sometimes the bevel rubbing bowl gouge worked best and sometimes a good sharp scraper. It depends on how the grain runs in the piece. I found a skew ground so the edge curved and used on it's side was often the best. I think because the sharpening angle is so fine compared to some scrapers. It might also have something to do with the negative rake as well.
Now I mostly use good sharp bowl gouges with the proper technique.
 
Just an aside, I found a difference also if the grain was horizontal versus vertical to the piece( with the segments glued side grain to side grain), I found the vertical direction having less tear out as you are cutting across the grain instead of into the end grain ( beginning cut) of the leading edge when glueing them end grain to end grain the down side is end grain to end grain glue up in the vertical instead of edge grain to edge grain, which may cause some weekness if the piece is to be used , Malcolm may have some insight to this , I also found in doing OT (Index / Rose engine) work on segments one should never have end grain showing , I always use edge grain in the vertical or horizontal to the piece depending which way the cutter is mounted and got way less tear out or none at all. Of course " scary sharp" tooling/tools and steady presentation are critical to smooth results and may be even more important as you get better at it. Like fine tuning ones golf swing once you learn how that mullagan happened .....😱
 
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