Rings oval instead of circular

[Mark McClellan]

for the first time I am making rings that the segments for me are quite small. 40 segments per ring at 4.5 degree cuts and About .375 thick, 0.40 width and 0.70 S.E.L. I used regular metal band clamps and the ring looked ok as I set it aside but when I came back after the glue dried some were oval instead of circular. I'm guessing that I cranked the band clamp too tight. Any comments on one what to do to prevent this in the future and second any idea if I can salvage the slightly oval rings, maybe break them in a few places and re glue? Thanks, Mark

 

[mfisher]

I have had rings come out as an oval after gluing. You are not alone. Some of the causes for me were:

- not all SEL were close enough to each other. That is some short or long causing the ring to not be a circle.
- excess glue in some joints changing the SEL.
- very thin segments warped due to glue moisture.
- metal band clamp not making a true circle. worm gear portion can force a segment out of alignment.
- stock used to cut segments not having parallel sides
Here is a clamp that I now use.

 

[Mark McClellan]

I have had rings come out as an oval after gluing. You are not alone. Some of the causes for me were:

- not all SEL were close enough to each other. That is some short or long causing the ring to not be a circle.
- excess glue in some joints changing the SEL.
- very thin segments warped due to glue moisture.
- metal band clamp not making a true circle. worm gear portion can force a segment out of alignment.
- stock used to cut segments not having parallel sides
Here is a clamp that I now use.

Thanks for the input. After cutting 600 segments I am at wits end. The only strong point I have in my repertoire is for all the years I have been woodworking I have gotten very good at fixing screw ups because I screw up so often so before I cut another 300 or so segments for the oval rings I'm going to try and salvage what I can, I mean the worst that can happen is I blow them up and have to cut now ones anyhow. Maybe I can salvage a couple or two. Thanks, Mark

 

[Charles Broadbent]

for the first time I am making rings that the segments for me are quite small. 40 segments per ring at 4.5 degree cuts and About .375 thick, 0.40 width and 0.70 S.E.L. I used regular metal band clamps and the ring looked ok as I set it aside but when I came back after the glue dried some were oval instead of circular. I'm guessing that I cranked the band clamp too tight. Any comments on one what to do to prevent this in the future and second any idea if I can salvage the slightly oval rings, maybe break them in a few places and re glue? Thanks, Mark

When working with higher segment volumes, you can't completely rely upon the segment angle cuts to bring it under hose clamp compression to a near-perfect circle like you can with, say, 12 segments in a ring. Something I have done with success is assemble the ring and begin to tighten the hose clamp encircling it all. I then measure the diameter of this ring vertically, crossways, and maybe a few other directions, pushing the longer diameter positions together or pulling the shorter diameter positions apart. Under light or moderate compression pressure, you will be able to manually adjust the ring until it is pretty equal no matter which way you measure the diameter, at which point you tighten the pressure and do your final checks before letting the glue set. You need to work reasonably quickly, because rings with a lot of segments take some time to assemble, and you need to complete the assembly and "rounding" before the glue sets. If that is a challenge, consider using Titebond extend glue, which gives you a little more assembly time.

 

[Mark McClellan]

When working with higher segment volumes, you can't completely rely upon the segment angle cuts to bring it under hose clamp compression to a near-perfect circle like you can with, say, 12 segments in a ring. Something I have done with success is assemble the ring and begin to tighten the hose clamp encircling it all. I then measure the diameter of this ring vertically, crossways, and maybe a few other directions, pushing the longer diameter positions together or pulling the shorter diameter positions apart. Under light or moderate compression pressure, you will be able to manually adjust the ring until it is pretty equal no matter which way you measure the diameter, at which point you tighten the pressure and do your final checks before letting the glue set. You need to work reasonably quickly, because rings with a lot of segments take some time to assemble, and you need to complete the assembly and "rounding" before the glue sets. If that is a challenge, consider using Titebond extend glue, which gives you a little more assembly time.

Charles, thank you that makes a lot of sense something I don't often exhibit when I get in a hurry. Patience is not my strong suit.

 

[mfisher]

You may want to look at Tom Lohman website for some tips on high segment rings.
His jig seems to be one answer to getting round rings when the segment count per ring is high.

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