Bamboo backed Ipe fracture?

[Rudamchu]

Hi y'all ... new to the site. I recently made this bamboo backed ipe R/D bow using Sam Harper's build along. It's 66" ntn, and 47# @ 28". I slowly tillered and had no problems with any stage of the build. After finishing the bow, I shot about 25 arrows through it, and upon inspection, saw what appeared to be some sort of tiny fracture about 6" from the tip of the upper limb emanating from a tiny knot that I had "stabilized" with crazy glue and ipe sawdust during the build. Should I be concerned? If so, is there a fix?


         

[Rudamchu]

 

 

[Bowjunkie]

Yes, you should be concerned. That compression fracture will continue across the belly and may ultimately cause the bow to cave in and break there.

Some folks have had success grinding it out and gluing in a healthy patch there using a method described by Dean Torges on his website. I have had success with it on bamboo backed osage, but the bellies were fully radiused. I don't know if those are important factors or not. It might be worth looking into.

Here's the link....

 www.bowyersedge.com/patch.html

[Onehair]

I'd wear a helmet until you figure it out.

[fujimo]

when i have done those patches, i found that they do like to move a bit on the edges of the patch- maybe the joints were too perfect and a mite glue starved- but what i do now as a matter of course , is a nice wrap with serving thread, and ca glue- and maybe do a corresponding one on the other limb - for looks- if you want! i dont usually bother.

[Roy from Pa]

When I encounter a problem like that, I cut the bow into pieces on the band saw and start another one. I know that patch has worked in the past and I also know it has failed in the past. I just don't want to take the chance of the bow exploding at full draw, and that has happened too after being patched..  It's pretty exciting though, LOL.. Just my opinion there..  

[fujimo]

yea- and the old fart is absolutely right Rud.
i know that its just hard to let the first one go. fix it, its good practice- then build another one- i guess thats kinda like practicing running away from polar bears, then moving to africa   :D  
but Roy is right- it can be a risk. so get cracking with the next one- after a few break- it wont feel so bad anymore      

[mikkekeswick]

As the others have said.
Ipe is strong, strong wood but I will never use another piece that has pin knots. They almost always chrysal eventually even if you get through tillering with no problems. Always use perfectly clean ipe.

[Msturm]

Yep.  I had a pin knot in a similar place. It went Bang!  I hurt my shoulder and put a splinter in my ceiling.

Good luck.

[Rudamchu]

Thanks for all your input and advice. I'll take it all into strong consideration, and I was already planning on beginning project number 2 ... Shooting for a 55#'er this time. Wish me luck and I'll post when I'm done.

[DCANAPP]

You might shorten the bow for a youth or child and start a new one for yourself. That's why my kids had awesome self bows when growing up and the granddaughter can still use them.

[Sam Harper]

I wouldn't give up on the bow.  Instead, grind the belly down and tiller it to something like 30#.  Then glue on a 1/8" or so slab of bamboo flooring to the belly, and retiller to your desired draw weight.  I've saved a few bows that way that had compression fractures.  Here's one that started off as a bamboo backed ipe bow (I used a crappy piece of ipe to begin with), had a compression fracture on the upper limb, and I fixed it with some bamboo flooring.  Now it shoot great and has no problems, and I've shot it a bunch at 3D shoots and stuff.

 

 

[Rudamchu]

Thanks for the advice Sam .... I like the sound of that fix better. Seeing as I used your build along for this bow, I think it's only appropriate that I give your suggestion a try. I will be making many more bows of various designs, but I'm gonna try salvaging this one first.

[Rudamchu]

Would you recommend that I use epoxy or titebond III for the belly lam? I originally glued it up with unibond in the hot box and I'm not sure if I should hot box it again.

[Sam Harper]

Use Unibond.  As long as your ambient temperature is over 72ºF, it'll harden.  You don't need a hotbox.  Just give it more time--at least 24 hours.

[Sam Harper]

Or, you could use your hotbox, but crack it open a little so it doesn't get as hot as the first time you cooked it.

[Sam Harper]

Oh, and while you're tillering the bow, before gluing the extra lamination on, try to keep the belly flat.  If you round it over too much, you'll have an ugly glue line when you glue the extra lam on.

[Rudamchu]

I assume that using a cabinet scraper would be a good way to tiller flat