[Bryverine]

So I just glued up all the laminations about 24 hours ago with weldwood and all seemed to be great when I heard some creaking and cracking as I removed the clamps in three spots.

There are three spots where it looks like the wood de-laminated a touch because I didn't use enough glue. I've been reading about de-laminating fixes and it seems like using warm weldwood to fill the "cracks" is a pretty good option.

Does this seem fixable?

See pictures below while keeping in mind that all the spots seem to be able to be clamped back together and all the laminations are 0.100" thick maximum for scale:

I also have a bit more gluing when it comes to this guy:

 

[Steve Neul]

Sorry but it's time to start over. Once you apply glue to the wood it seals the wood and regardless of what adhesive you try to glue it again it never holds under that pressure. You either need to use thinner layers of veneer or pre-bend them with steam so it isn't under so much pressure when you laminate them.

 

[johnnie52]

I wouldn't try to fix that. It may look fixed, but the first time you string the bow it will delaminate again, only worse.

 

[Bryverine]

Well that's a heart breaker. Bummer of a first time bow. I guess I'll start over and perhaps use a different glue this time... there goes $175 dollars + many hours down the drain.

Thanks for your guys replies.

 

[woodnthings]

try crazy glue

It won't cost anything to try it. I would also check in at an archery site before giving up. You can inject the crazy glue with a syringe and if the laminations can be compressed back under more clamping pressure, that should do it. see your visitor messages...

 

[punkin611]

I don't know a thing about gluing up bows but You need a glue with very low "CREEP" How 'bout Hide glue?

 

[frankp]

Beautiful design on that bow but I think you missed the boat. I don't agree that it's impossible to repair delams but in this case I think it's too far gone. I personally wouldn't ever trust shooting it again unless you peeled back all the lams that split, sanded them all down and then tried again. Thinner laminations would definitely make it less likely to delam like that in the future.

If you want to try peeling them back, use a heat gun and slowly separate the layers. It's a long slow process and you may end up doing more damage but I've seen people do it successfully on other laminations (not bows).

 

[afx]

Why can't you just take a router bit with a 1/4 bearing on it and take off 1 layer of ply then repeat until you've taken all the affected layers off, then you can take a small sliver of the top glued layer and add more layers to laminate on top of that?

 

[TimPa]

Well that's a heart breaker. Bummer of a first time bow. I guess I'll start over and perhaps use a different glue this time... there goes $175 dollars + many hours down the drain.

Thanks for your guys replies.

any cracks in blow limbs should not ever be put under pressure, even if you squeeze some glue in to fill the gaps. hang it on the wall as a reminder for next time. as mentioned, you need much thinner strips to make those bends.

was there really $175 in materials on that glue up? is weldwood the recommended glue type for bow laminations? just curious.

I applaud you for trying this project, it looks interesting.

 

[Bryverine]

Well I guess I'm going to try to fix it and see what happens anyways. I'm so far in after about 6 months of planing, drawing, modeling, finite element analysis, material calculations, designing, cutting, shaping, etc. that I can't just give up even though I'm now pretty sure that it will not work after all the experience above told me so. But can you blame me for trying? I'd rather it break (safely of course) then to stop and never really know if I was the one exception to the rule.

I bought a board of Osage about 6'x6"x1.5" (most of which was unusable after I looked closer at the grain/knots/rays in the wood), maple 3'x12"x2", purple heart 2'x1.5"x6", wenge 6"x6"x2" (that one wasnt too bad), and the hickory backing +shipping. Not to mention the blades (thin kerf) for cutting the laminations, the jigsaw blades, bandsaw blade, glue, etc.

I have read alot about glues and the weldwood plastic resin glue (urea-formaldehyde) is supposed to be pretty good. I just think I was too thin on application because of the tiny brush I had. The thickest lamination was the hickory (which I bought pre-cut) measuring in at 1.145" the rest were all around 3/32 (or less) all of which were heat bent to close (but not close enought apparently) shape before glue up.

I appreciate all the replies, this was supposed to be a bow for my wife after she bought me one, I guess it was an expensive lesson in woodworking. Next time I'll cut 1/16 strips and get better wood for cutting laminations. Come on tax return...

 

[Quickstep]

On my last lamination, I used Resorcinal glue which I think is similar in some respects to Plastic Resin Glue. Since there are a lot of surfaces to get glued up, it's important to make sure they're staying wet until they get clamped. If the glue begins to dry, or gets absorbed by the wood, that joint will lose strength. Keeping the clamping pressure even is also key. Since bending the laminations create pressure at the bends, using lots of clamps to even things out is important. I'd use a clamp every couple of inches if not more. For what it's worth, some of those bends look a little tight for wood that's 1/10" thick. The wood's tendency to resist the bends can make for uneven glue thicknesses at those joints. Best to have the wood be pretty compliant on the tighter bends. Lastly, it's best never to rely on glue to fill a joint. There's some latitude with epoxy, but for the most part glues don't have the strength to fill gaps

 

[TimPa]

one more thing to consider, think i saw it on woodright show. sawing a board will result in grain coming and going to the board surfaces. you may consider trying to split the wood along the grain, as the result will be considerably stronger.

 

[Bryverine]

one more thing to consider, think i saw it on woodright show. sawing a board will result in grain coming and going to the board surfaces. you may consider trying to split the wood along the grain, as the result will be considerably stronger.

That's actually why most of the board was useles, I had to cut the board at a 53 degree angle to prevent grain runout. I put quite a bit of time into this baby and had to jump through quite a few hoops along the way.

 

[woodnthings]

we have static load lamination experience here

Well I guess I'm going to try to fix it and see what happens anyways. I'm so far in after about 6 months of planing, drawing, modeling, finite element analysis, material calculations, designing, cutting, shaping, etc. that I can't just give up even though I'm now pretty sure that it will not work after all the experience above told me so. But can you blame me for trying? I'd rather it break (safely of course) then to stop and never really know if I was the one exception to the rule.

That's why I suggested an archery site or the person I recommended.
You have dynamic loads in play and that's a whole 'nother ball game.
Never hurts to ask advice, you just have to know which is the best.