When making segmented blanks, how are you measuring the length of your segment edges?

I want to try my hand at some segmented rings.
I've got the Segmented Projet Planer software.
I draw my vessel, and on one ring, the length of my segment is to be 1-25/32" long.

20 segment ring.

First of all, how important that each segment be 1-25/32" long...on the dot?

If I need to be dead on, within 1/32, how are you guys measuring your segment lengths, before you cut them, to achieve this?
 
Sue, I'm not a segmenter, so take this with a grain of salt, but I believe the very good segmented turners like Malcolm Tibbets use digital calipers to measure their segments, and they're shooting for a lot closer tolerances than 1/32". Malcolm uses various jigs for cutting and sanding his pieces, so once a jig is dialed in, he doesn't have to measure each piece. But while getting things set up, the more accurate the cuts are the more accurate the finished work will be. A 1/32 difference between two pieces of wood on a table is no biggie, but a 1/32" difference on a dozen segments in a ring can add up to problems.

That said, if the error is consistent among all the pieces in a ring, as long as the angle is right you'll still get tight joints. The ring will be a bit smaller or larger than you'd planned, but it'll still be structurally sound.
 
Sue, I'm not a segmenter, so take this with a grain of salt, but I believe the very good segmented turners like Malcolm Tibbets use digital calipers to measure their segments, and they're shooting for a lot closer tolerances than 1/32". Malcolm uses various jigs for cutting and sanding his pieces, so once a jig is dialed in, he doesn't have to measure each piece. But while getting things set up, the more accurate the cuts are the more accurate the finished work will be. A 1/32 difference between two pieces of wood on a table is no biggie, but a 1/32" difference on a dozen segments in a ring can add up to problems.

That said, if the error is consistent among all the pieces in a ring, as long as the angle is right you'll still get tight joints. The ring will be a bit smaller or larger than you'd planned, but it'll still be structurally sound.


Yes, I realize this.
I'm trying to figure out what sort of jig to rig up.
 
You might check out Malcolm Tibbetts' book or DVDs. I think he shows some jig ideas in them.

As I recall, Malcolm uses a sliding compound miter saw to cut his segments to rough length, then uses a jig on a big disk sander to get to the final length. I know some other segmenters use a table saw sled for cutting their segments, but don't recall how they set them up for cutting the exact angles and lengths they need.
 
Sue, I don't actually measure the segments as such before cutting, just check the jig stop settings on a scrap piece.
Now Jig is rather a grand word as I use a chop saw to cut my segments.
(It's essential that the blade and support base are set up square to get a true 90deg.cut)
I just have a simple adjustable stop fence to locate the first cut edge on for narrow segments.
For wider segments for lids where I use a lot of small offcuts up I use a simple pencil line on the Left Hand Fence to set the width.

See attached images.

I find that by using my calculator with a bit of size padding added to cover dimension and glue up errors that the method is close enough.
 

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Like Vaughn said, Tibbett's book/DVD is a very good reference for segmented turners.

For simple segments, a table-saw sled works just fine.

http://semiww.org/wiki/doku.php/members/segmented_bowl_table_saw_sled

For more precision and particularly for feature/design rings, a disc-sander jig is needed. I think Curt Theobald also uses a jig like that in his DVD
http://www.curttheobald.com/store.html

This is how I calculate segments without any software:
http://familywoodworking.org/forums/showthread.php?t=11646&highlight=segmented
 
Sue I to use a table saw sled nothing fancy just enough to hold segments and a stop block to keep each piece the same size. as far as dimensions you can be off a little but the more segments the dimensions become more critical .
 
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