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What went wrong?

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What went wrong?

Postby Chemsolder » Fri Mar 28, 2014 12:02 pm

Okay so this one was getting ready to shed a few lbs and final tiller and as I always do I drew it to anchor at my ear, not shoot just make sure all is good right around 33" measured with tape not using a bow... :shock: pop and subsequent collapse and a scratch on the hand. Scary but not terribly harmful to anything but confidence... :oops: More than anything glad it happened to me and not anyone else. So now we get to play where did it break, my guess is slightly above the section where the split in the belly lam is what let go...there is a spot where the glue split but took neither of the lam above and below with it. This makes me think I must have gotten contamination on glue up in this spot every other spot seems to have good adhesion and wood stuck to it with one other exception the bloodwood at the back of the riser. which I cant imagine is getting much flex because of where it is on the riser. feeling a bit disgusted right now, I knew it would happen sooner or later but come on..this was bow #13 maybe was just meant to be.

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Thanks for the ideas in what caused the disaster.

Glue up procedure on this one was to lay out wax paper clean one side with acetone and place on paper
then clean other side let dry 10 or more minutes
mix glue and let warm apply glue to both touching sides stack and clamp it all up apply heat and cook leave in form 24hrs and remove.

Just remembered as I was typing this I had to unclamp one limb and reclamp as the lams had slid down a bit, could that be the problem? if I had tape on the belly still I could tell if this was the limb ugh... I'm going to lick my wounds and order more glass...
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Re: What went wrong?

Postby Crooked Stic » Fri Mar 28, 2014 5:58 pm

The first thing I see is wax paper the second is acetone. You can get by with cleaning the glass with acetone. I sure do not use it on the wood parts. Then if any of the acetone got on the wax paper you probably got some contamination there to. I am not sure wax paper is your best choice for glueing either. Now what I can see in the pics is maybe the glue let go there on the belly ramp.
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Re: What went wrong?

Postby Chemsolder » Fri Mar 28, 2014 6:47 pm

Yeah this is only one ive used wax paper as a surface to glue on I started thinking about it more and that may very well be part of the problem. Well more than maybe I think...put a little acetone on the paper complete no go. Acetone went right through and paper was real slick. My guess is the lam picked up some of that wax before it was glued. I dont think ive ever not wiped one with acetone as far as woods, but it is always a very light wipe with little acetone and a wait time before gluing, but I think going forward I will completely avoid it. Dang hate expensive lessons
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Re: What went wrong?

Postby tattman2 » Sun Mar 30, 2014 12:59 pm

Wax and glue :o I use freezer paper for glue ups.I sort of treat glueups like an operation :) Lots of lights to make sure there is complete saturation of glue and a super clean environment and gloves to keep from contaminating the wood and glass.I shut off the outside world,turn on the Hank Sr and start operating 8-)
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Re: What went wrong?

Postby Chemsolder » Sun Mar 30, 2014 10:16 pm

Operation definitely...just grabbed the wax paper cause had no more butcher paper or painters plastic, which would likely cause problems if acetone got on it too. Oh well live and learn.
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Re: What went wrong?

Postby Kenro » Wed Apr 02, 2014 10:12 pm

Crooked Stic wrote:The first thing I see is wax paper the second is acetone. You can get by with cleaning the glass with acetone. I sure do not use it on the wood parts. Then if any of the acetone got on the wax paper you probably got some contamination there to. I am not sure wax paper is your best choice for gluing either. Now what I can see in the pics is maybe the glue let go there on the belly ramp.


^^^^What Mike said!. These are the first things that would have thrown a red flag at me!
I don't ever use ANY chemical of any kind to whipe on anything!!! sand it....then blow off with compressed air. and then never handle any of the gluing surface areas by hand.(just saying this is what I do)

The next thing was in mixing of the glue. I cannot stress enough to people how important this part is! Especially if the glue is only avg room temp (65-70*) That's just a fuzz to cold IMO. anytime the mixing is to take place, I want the parts A and B to be warmed up a little. 75 to 85* and 5 minutes BARE MINIMUM mixing time! If you're hands don't cramp up while mixing you aint trying hard enough! :D (If its around 65* in your shop.....id stretch it to 10 minutes of mixing!) and then let it sit for about 10 minutes before using. Good induction of these two parts is SSSOOOOOOO important!

I see areas in your break where you DID lose adhesion and likely is where it all started. If it winds up where all the wood cores are all splinterd out (which then shows the glue did its job)..then I would say it was either 1)major flaw somewhere in the core that you didn't know about...2)or was severely overdrawn... or 3)(not likely)...a design issue..ie. steep abrupt fades...short working limb etc.

Don't sweat it.....after a few hundred bows you'll forget all about this one! ;)
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