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Segmented Ring Gluing Question

D

Doug Reesor

Joined
Jan 7, 2009
Messages
6
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1
Location
Lancaster, PA
Website
www.morebitstoturn.com
I have been practicing gluing segmented rings for about 1 year now and have been working to improve my technique. One of the frustrations I have been dealing with is the glue lines that do not meet my goal for consistancy. I have checked out the dry fit and can find no gaps when held to a light as recommended by Malcom Tibbets, but when I glue the half rings together they are out of round. Similarly I find the condition when I do full ring gluing.

I have heard some people say that sanding the segment after cutting makes it better - the caviat to that is that your sander has got to be more accurate than your saw or it can make the problem worse - it is extremely important to get a sander with a very solid table so I went out and bought a higher quality disk sander.

I am wondering about 2 things - clamping pressure and seperating pin placement. Is it possible that I am trying to hard to get the rings tight and using too much torque on the hose clamps I use which then leads to ring distortion? Also, if you are using a pin to seperate the ring halves, is the size of the pin or exactly centering make a big difference?

Doug
 
Hey Doug, welcome to the forum. There are several answers to your questions, and opinions vary. Here are some: If your segments are cut with a good quality crosscut blade (sharp, 80 tooth carbide) the cuts will be smooth, flat, and not require sanding. The bottom edge of the cuts can have a bit of "fuzz", which should be sanded off w/ sheet of sandpaper on flat surface (saw table). "Perfect" glue surfaces do not require clamping. I glue segments two by two, up to half rings. Simply rub the two surfaces together until you feel them begin to "grab". Align and press together for a few seconds. The ends of half rings rarely align perfectly, and can be sanded flat (disc sander) so the two half rings match, removing as little material as possible. The resulting rings will be slightly out of round. Mark the glue joints and keep them pointed in essentially the same direction as you build the work, as this will help maintain good pattern alignment in the whole workpiece. If you are having to sand more than a little material to get the half ring ends straight, adjust your cutting angle. Some folks claim they can make perfect cuts, and I have done so, but not consistently. Others will follow here with additional suggestions. Good luck.
 
I actually have found that if I dry fit the ring, clamp it with a hose clamp, and see no gaps with a bright light, I will go directly to gluing up the whole ring at once...not half rings. However, a tiny bit of grit, sliver of sawdust, or dried glue, can cause a joint to be wider than expected, so cleanliness is important. Make sure you hand sand each segment to get rid of that fuzz.

With half rings, I place the pins very close to center of the width. I use pieces of 1/4 or 3/8 dowel...they seem to work fine. The smaller the dowel, the easier it will be to see if the assembly is out of round. Also, make sure the outside points of each segment line up. If one is off a bit, it can throw the assembly out of round. So use plenty of glue...it will give you more open time as you line things up.

Clamping pressure is a judgment call. Dale Nish quotes Ray Allen in his woodturning book to clamp hose clamps "two-hands-easy"...whatever that means. Although the pictures shows him using a socket head screwdriver, and gripping it with both hands to tighten...so it must be pretty tight.

I've found that if I do a rub joint, then put finger pressure on a pair of segments until glue stops squeezing out, that is enough.
 
Segmented rings

I would recommend " Wood Turning With Ray Allen " by Dale Nish. It answers evryone of your questions and shows how to cut, sand, clamp and glue.

Ray Allen was a master, his work is breathtaking.
 
Doug, you've received lots of good advice. For what it's worth, I almost always use the "half-ring" gluing technique. I don't always sand all segment ends, but often I do. Excessive clamping pressure should not be necessary. The only reason to apply any pressure is to drive excess glue from the joint and to keep things in place until the glue sets. On small rings, under about 7" diameter, I usually use rubber bands. Bigger than that, I use hose clamps,
but again, with only enough pressure to force the excessive glue from the joints. If your project requires segments that are only one inch wide (outside to inside), then before cutting your "good stuff", spend a little time cutting cheap wood into segments that are two to three inches wide (length doesn't matter as long as it's consistent). The "super sized" miter joints will quickly tell you if your saw's miter angle is dead on.
 
I haven't done enough of it to justify a blanket recommendation, but I've found that if the fuzz is only on the outside of the cut, slicing it off with a sharp knife is better. That portion gets removed in final turning anyway. Sanding the entire face could destroy an almost perfect first cut. Probably works inside too.

Joe
 
Joe Greiner said:
I haven't done enough of it to justify a blanket recommendation, but I've found that if the fuzz is only on the outside of the cut, slicing it off with a sharp knife is better. That portion gets removed in final turning anyway. Sanding the entire face could destroy an almost perfect first cut. Probably works inside too.

Joe
Click to expand...

Joe, it makes little difference how the "fuzz" is removed; any rounding on the edges is removed when the rings are flattened. As for sanding the end-grain glue surfaces, it mostly depends upon the quality of saw blade surface that you can achieve. If the naked eye can see evidence of saw blade scoring, then the surface can be improved with an accurate disc sander jig. If the saw blade produced surface can't be improved, then it's probably a waste of time. Another consideration, and this is probably very minor, test have confirmed that sanded surfaces results in a stronger glue joint - not a big deal, but something to consider. The bottom line is "do whatever it takes" to produce the best looking glue joints. Dark glue lines, usually the result of imperfect surfaces or fit, especially between light colored woods really detract from the appearance of a segmented turning.
 
Thank-you everyone for you comments and input. I have tried some turning of "plain" wood and find the experience rather hollow. I guess it takes a special kind of crazy to do the segmenting and I am hooked completely! It is a much fun putting the puzzle together as it is discovering how it looks in the final form on the lathe. Each time through so far, I am so annoyed at my mistakes I have to try again to do a better job next time and as soon as I am satisfied another pattern or idea pops to mind which has got to be done.

Cheers,

Doug
 
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