Verticle Cracks in limb glass

[quail]

Friend of mine has had some recent problems with the glass on takedown limbs developing cracks along the length of the limbs. Thoughts on what could be causing this?

[heartlandbowyer]

How old is the bow? What is the bows weight and how much do the arrows he is shoot weigh. I wound have him retire the bow before it fails if the cracks are getting longer.

[Swissbow]

I had a similar problem once where some weeks after glue up the bow started to develop cracks over the length of the whole bow. I think the lams had still to much humidity at the glue up. In the end I even had the lams separating partially from the riser.

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Andy

[Dale in Pa]

I had some problems a while back with several bows,TDs and 1pc, developing lengthwise cracks.Never had that problem before.

Personally,I think it was the glass,I was ordering from a popular mail order trad supplier and was probably getting UL instead of ULS.

After getting back to ULS,haven't had any more problems.Mike Fedora told me the other day they don't even buy UL glass.After 40 years or so, I think the man probably knows what he's talking about.

[Dan Bonner]

If the cracks start at the limb bolts it could be drill chatter from a dull bit.

Bonner

[kennym]

If in doubt whether it is ul or uls on clear, hold it up to a bright light and you can see the scrim in it, as lines across the glass show up a little less than 1/6" apart. Gotta do it before gluing the limb up tho...

Dan, I have also wondered on the splits at the drill holes, if the wedge drew moisture from not enuff finish.

Also overtightening will cause a split.