Segment ring dry time

Discussion in 'Woodturning Discussion Forum' started by Gary Beasley, Oct 27, 2017.

  1. Gary Beasley

    Gary Beasley

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    Having recently started segmentation I've just noticed bowls I've turned developing ridges where the ring has shrunk a bit after finishing. My take on this is the wood glue is adding a lot of moisture to the wood, and as it dries the ring is shrinking. Is this the usual problem in segmentation? Knowing this, how long should a glued up ring be allowed to "cure" before stacking if it makes a difference. Should I leave the glued up bowl blank to dry like a roughed out blank and for how long?
     
  2. Mike Johnson

    Mike Johnson

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    The wood species will make a difference as to how much moisture is readily absorbed.
    I usually glue the segment rings and let them dry and plane them or sand them flat.
    A few extra days of the individual rings exposed to the air will help them dry.
    Using a moisture meter may help in determining if you have moisture issues from the glue.
     
  3. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Glue creep is a very common issue in all types of woodworking and with several different kinds of glue. There are various factors that cause it. One of the main causes is seasonal movement of the wood that creates very high stresses in the glue. Because wood moves, most kinds of wood glue never gets completely hard. The best solution to the problem is to avoid putting too much glue in a joint.
     
  4. john lucas

    john lucas

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    I have had that problem. It's very hard to turn a piece and then let it dry for more than overnight before final finishing. In fact most of us will pretty much finish it that day. We should probably wait longer but I would have to ask the true segemented experts how long. I have a piece that I did take my time building. It's all out of one wood because it was a competition about form and the piece had to made out of one wood. It was perfect for a year or so. It now has those little bumps as well. So hopefully the experts will chime in and tell us what they do. I will ask one this morning. I'm going to a club function and one our turners is very very good at segmenting and has probably asked others about this problem since he also goes to the segmented symposium.
     
  5. Andy Chen

    Andy Chen

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    Welcome to segmenting, Gary. To start with, one should always kiln dried wood for segmenting. Even so, do expect "glue creep" over time. The consensus among segmenters nowadays is the glue does not creep, rather it's the wood movement that creates those line between segments. It'll happen even with kiln dried wood and even the same species or even pieces from the same board. Of course it's worse when you mix different species, which us segmenters love to do. As to how long you have to wait for the glue (wood glue of course) to dry, I usually wait no more than 2 h on each ring. Heck, I have started stacking rings in 20 min during demos. However, after the entire vessel is finished it is probably a good idea to let it sit overnight before you do the final sanding and put the finishing on.

    It you do sell them just be honest with the client that over time they will feel lines between segments (rings as well) and that's just the nature of the beast. If they don't like it maybe they should go for pottery but my segmented bowls are one up on the pottery because my design goes through the wall and not just painted on the surface.:p Or, they can buy my Corian turnings which will always be silk smooth.

    Enjoy segmented turning.
     
  6. Gerald Lawrence

    Gerald Lawrence

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    This is also a problem with flat work . Andy has more or less got the answer. The moisture in the glue causes the wood to swell . In flat work if you surface the work while the wood is still raised it will leave a slight valley when it dries. I am not sure how this relates to segmented but it does tell you something about wood movement and its causes. I would think the longer you can let it dry before final cuts are made the better. Still the long term answer Andy gave is great.
     
  7. Bill Boehme

    Bill Boehme Administrator Staff Member

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    The worst case of glue creep that I ever encountered was when I used hide glue to assemble a cedar blanket chest. I suspect that the resin in the cedar was a contributing factor because the problem went on for many months in a few spots where there was probably too much squeeze out during assembly. On flat work it is relatively easy to remove the ridge of glue with a cabinet scraper. That would be a little trickier on a curved surface.
     
  8. Gary Beasley

    Gary Beasley

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    John I haven't heard of a segmentation symposium. Can you point me towards the one you refer to?
    One thing I worry about when glueing the stack is glue gaps, and even though I built a ring press and use it getting perfectly flat rings is a challenge. I tried the drum sander but it seems to snipe a bit. The disc sander is only good for smaller rings. Best I've come up with is a flat board with sticky sandpaper.
    I also tried to get one of those adapters to put a chuck on the tailstock to help with ring stacking but it was made for Oneway live centers and mine turned out to be a not so perfect clone that didn't fit the adapter. Have yet to fix this problem. Thanks for your thoughts on this matter. I might resort to treating this like like rough turned green wood after glueup to let the structure stabilize.
     
  9. Bill Boehme

    Bill Boehme Administrator Staff Member

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  10. john lucas

    john lucas

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    Gary I talked to my segmented turner friend today and he varified what I thought and what Andy just said. It's wood movement that causes the bumps not glue creep. I did some research for a while and you can find wood movement charts online for all species. Nobody does it but if you buy woods that have the same movement ratios you could feasibly glue up a bowl and not have it move. Of course you would also have to orient the grain the same way on every ring.
    I have tried most of the ways to flatten a ring. You have to find what works for you. A disc sander works but there is a learning curve. Same with a thickness sander. I have put rings on the lathe and flattened them carefully by shear scraping. I have also just used sandpaper glued to a flattened board both on the lathe and just on my workbench. Slow but it does work. I have made rings that were only 1/8" thick and the sandpaper on a board was the only way to flatten those. Just keep at it and you will find a way that works for you.
     
  11. Bill Boehme

    Bill Boehme Administrator Staff Member

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    John, what I have seen in flat woodworking is far too much to be just wood movement. In rail and stile joints in the cedar blanket chest that I mentioned above the thin glue ridges were on the order of 1/16". I would scrape it off and a few weeks later there would be a new ridge. It's been about 20 years since I built it, but I think that it has settled down.

    Some "experts" claim that hide glue doesn't creep, but I beg to differ since I have experienced it big time. Cedar might be a special case because of the outgassing of resins.

    Here is some information that I found on glue creep
     
  12. Gary Beasley

    Gary Beasley

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    The one bowl I have on the table now is 100% white pine, the ridges are quite noticeable. You would think it would all shrink together but it don't. It might have something to do with ring diameter, ratio of diameter to segment width, whatever. I'm going to try resanding and refinishing and watch it to see if anything else happens.
     
  13. Andy Chen

    Andy Chen

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    #6 will be in St Louis next year. There is a segmented chapter and here is their website, http://segmentedwoodturners.org/. You'll find a lot of useful info there. Also, you are pretty close to Arrowmont and they have classes on segmented turning just about every year. If you don't mind traveling to Indianapolis Marc Adams has segmenting classes too.
     
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  14. john lucas

    john lucas

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    I didn't notice you were in Marietta. There is a club that meets outside Atlanta on the east side of I20. Can't remember the name but I've demoed there a couple of times. they meet at Don Russels house. Don is a fantastic segmented turner and a hell of nice guy. If you can get in touch with him you can get all of your questions answered. There are clubs all over Atlanta. I have demoed at them all. My mother lives in Atlanta so I visit there a lot and it saves them money on my demos since I can stay with her. I will be trying to go the St Louis segmented sympsium. I have an Uncle who lives there and plan to visit him.
    Don usually teaches a class at John C Campbell folk school. If you ever get a chance to go there it is a blast. https://www.folkschool.org/
     
  15. Mike Johnson

    Mike Johnson

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    Here is my 2-cents on this topic.
    After the wood project is finished (segmented or flat work) the relative humidity can change in the
    environment that the wood project is exposed to. As the wood piece absorbs humidity from the
    surrounding area it will expand, as the humidity level decreases the wood can lose moisture content
    and shrink. All of the glued wood joints will end up compressing the glue in the joint forcing a percentage
    of the glue above the surface of the wood joint. Most flat work projects will incorporate an expansion joint for wood movement on large surface areas. A segmented piece has no way of providing for expansion joints and all of the glued joints horizontal and vertical will exert forces in various directions based on the grain orientation. Starting with kiln dried wood and letting the turned piece dry completely before sanding and finishing will reduce the amount of glue creep. Having a number of projects to work on will decrease the temptation to speed through a project and allow drying time for each project being worked on. Most bowl turners will have plenty of turned bowls to work on in various stages of completion.
     

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