Are longitudinal cracks in bamboo normal?

[AndyTurner]

Hi.

Following glue up, a hairline crack that has appeared in my bamboo backing. I could just fill it with glue and sand back but the bow is for my daughter and I don't want it blowing up on her. So far I've only glued up 3 bows and this is the first time I've seen it.

Is this normal?
Is it safe to just fill?
Do I need to start over??

Thanks,
Andy

[AndyTurner]

PS. Pic attached.

[Pat B]

Just like with bow wood, checks are a result of the boo drying foo fast. I don't think it would be a problem if kept in the center of a limb. Super glue should stabilize it.

[AndyTurner]

Hi Pat, thank you for the reply.

1. By "checks" - do you mean cracks?
2. By "bow wood" - do you mean core woods?
3. In terms of glue. I can see that "Super glue" would soak into the crack very easily and easy to apply but EA-40 seems stronger to me. So, EA-40 or Super glue?
4. Not sure how central on limb it is atm. I centred tips on thickest portion of boo. See pic. Will need to clean up first then assess.

Thanks again,
Andy

[Hamish]

+1 what the Pat said.

One little tip that helps with getting glue into cracks is to use a vacuum cleaner on the opposite side of the crack to suck glue deep into the crack.

I would make sure that you have at least roughed the thickness, and flattened the base to reduce the depth that the glue need to travel.

[AndyTurner]

 
"use a vacuum cleaner on the opposite side of the crack to suck glue deep into the crack" - unfortunately theres a Walnut core on the other side of the crack. I'll try the bouncy castle inflator on the backing side!!!
Actually, in all seriousness perhaps just a hair drier on the backing side might just push the super glue deeper into the crack
 

Thanks Hamish,
Andy

[Pat B]

Thin super glue will soak into the check(drying crack). You may even do it in a few applications. As long as the check follows the grain of the boo, which it normally does, it shouldn't be a problem. Trim the boo around the core and see where in the back of the limb the check is.
By bow wood I guess I do mean core wood. 

[AndyTurner]

Good morning chaps. Sorry I went to bed last night. I was shattered!

Thank you for all your input. I'll get on with it today and see if I can make it work. I've given it tug and it feels like it wants to be a bow! :0)

Have a great day,
Andy

[PatM]

I think the problem is from what appears to be a full width backing glued to a narrower belly.  Your clamping likely split the backing  from the pressure on the edges.

[HH~]

Pat is correct too. You cant have yer Boo handing off your core by much if your wrap it all to secure it.

Usually its does that with bamboo that was forced dry. Then boo takes up moisture again (cuz it is not seasoned), you use it then, it's glue down and loses moisture as it ages and it split on long axis. Very common using force dried boo.

Does not hurt your bow just looks like crap. You can fill with gap filling super glue. hen dye you backing dark. You never see it.

HH~

[PatM]

The bamboo will also be way too thick when you reduce the width.   You need to shape the bamboo and taper before glue-up if you want the thickness to be OK.

[DC]

Sorry for the silly questions but we don't know anything about you experience as a bowyer. Did you sand the inside of the bamboo nice and flat? The boo should be about as thin as you can get it and still cover the belly wood. For a typical bow it would be in the neighbourhood of 3/16" in the handle area and 1/16" thick at the tips.

[Eric Krewson]

Bamboo cracks are pretty common, superglue it and forget it, I have never had a super glued crack in bamboo cause a problem.

[Selfbowman]

Not if they are this big.
Arvin

[HH~]

Cheers to the King!

HH~