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Cinderblocks for gluing?

Discussion in 'Luthier's Corner' started by jordan_frerichs, Mar 25, 2009.

  1. jordan_frerichs


    Jan 20, 2008
    I need to glue some thin woods together, and they are each about 3-6" wide and all about 25" long. I do not have many clamps, but i do a few cinder blocks. Could i get by with the cinder blocks for this one? What is the safest way of gluing the faces of thin woods together, without a risk of them cracking, or getting a bad join?
  2. Sounds plausible. You might want to tape the joints together to keep from slipping apart & use a large(larger than the entire piece to be glued)caul to keep the pressure nice & uniform/even. Try it on a couple of testers first. I plan on using something similar in the way of large weights to glue tops onto my(long-stagnated)EUB bodies.
  3. vbasscustom


    Sep 8, 2008
    +1 on the testers, cause, if it frigs up, you really have no way of fixing it, because the wood is thin
  4. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    Mind you, I haven't tried this, but I think you'd need an awful lot of cinder blocks.

    Figure it might be reasonable to glue something like that up with, say, six clamps if you use a proper caul. I just looked up that Bessey's lightest-duty woodworking clamp (a quick-release clamp) applies up to 260 pounds of force; a medium duty clamp is 600-800 pounds max load; some of them go up to 1500 pounds. So, six light duty clamps, if they were tightened to only half their max load (and you'd probably use them closer to their max) is still over 750 pounds of force. You'd have to stack 750 pounds of bricks to equal that force.

    Or, consider that people use vacuum bagging successfully on veneer work like this. If you pull a decent vacuum, I'm guessing you get close to atmospheric pressure, so maybe 14 psi (pounds per square inch). That doesn't seen like a lot, until you figure that a 4" x 25" board is presenting 100 square inches, and so is getting a total of 1400 pounds of force.

    That's a lot of cinder blocks.

    Clamps are actually pretty awesome things.
  5. LedBelli Bass

    LedBelli Bass Fine, Handmade Custom Bass Guitars

    Dec 25, 2008
    Pasco, WA
    +1 w/jones

    Whatever you do, you need to compress the glue layer sufficiently to bond the wood without voids. Cinder blocks (unless you have a car parked on top of them . . . DON'T DO IT JORDAN!) don't provide enough pressure to squeeze the bond.

    Maybe you could borrow some clamps. How'd the school shop thing turn out?
  6. bronzehydra


    Oct 14, 2008
    Mukilteo, WA
    I've tried to do something similar to this, and it did not work at all.
    There was almost a 1/2 mm of glue between the wood in some parts of the pieces. Doesn't sound like much, but if you look at it, it's really obvious

    Clamps ARE awesome things.
  7. T2W


    Feb 24, 2007
    Montreal, Canada.
    You can use duct tape. apparently it works miracles, miracles with 13 strings..
  8. Greenman


    Dec 17, 2005
    Ontario Canada
    Put a 1500 lb. clamp on one side of a body/top lam and I could split the other side easily so you have to take in per square inch factor.
  9. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    Right, the force has to be distributed, hence the mention of using cauls, many smaller clamps, or the fully distributed pressure of a vacuum bag. The numbers I used were meant to address the sizes in the OP. Someone here, Alan Cringean maybe?, uses a welded steel frame for neck lamination, that has either one or two screws capable of very high force, but also uses a steel beam to evenly load the workpiece.
  10. jordan_frerichs


    Jan 20, 2008
    Yea, i tried it on some scrap mahogany, and it was horrible. I think i will get a few parallel clamps, and sandwich the wood i am gluing with strips of 3/4" scrap, 2 clamps per side and do this in at least 3 places, depending on what i can buy right now. Any other suggestions?
  11. Greenman


    Dec 17, 2005
    Ontario Canada
    Robbie uses brute force. :)

  12. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    I remember that one. Seventeen equally spaced "clamps!" Sweet.

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