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Main Boards => The Bowyer's Bench => Topic started by: Lee Lobbestael on July 25, 2019, 05:47:41 AM

Title: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 05:47:41 AM

I recently built a hybrid long bow for my brother and after 60 shots it blew up. I didn't get pictures to help me diagnose why yet. I was very confident on it. The glue lines looked great and it was around the tenth bow off of that form. I did clean the laminations with 91 percent isopropyl alcohol prior to gluing. Is there something in this that could cause a delamination?

Title: Re: Had a bow blow up
Post by: Crooked Stic on July 25, 2019, 07:34:28 AM

I use NO chemicals on the wood. I do clean the glass with acetone.

Title: Re: Had a bow blow up
Post by: pditto613 on July 25, 2019, 09:02:25 AM

Did the bow separate at the glue joints or did it shear the wood lams?

Title: Re: Had a bow blow up
Post by: Shredd on July 25, 2019, 09:05:25 AM

Not saying that this is the cause but 91% means 9% water... Did you use alcohol on the wood lams?? I would like to see pics of the bow, strung, unstrung and at full draw... Close-ups of fade area and break area...

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 09:13:29 AM

This is the only picture I have so far

Title: Re: Had a bow blow up
Post by: Flem on July 25, 2019, 09:25:20 AM

That does not look like a glue line failure. More like the wood grain sheared at the fulcrum created by the riser. Did you use highly figured wood lams?

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 09:35:57 AM

No very straight grained ash lams

Title: Re: Had a bow blow up
Post by: Flem on July 25, 2019, 10:43:32 AM

OK then, I'm out.

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 10:51:59 AM

Ha yeah I am stumped too

Title: Re: Had a bow blow up
Post by: Shredd on July 25, 2019, 01:36:28 PM

Welllll...  That's standard failure area...  Waiting for more pics...

Title: Re: Had a bow blow up
Post by: monterey on July 25, 2019, 02:41:53 PM

Just my SWAG but I think the glue joint failed on the face side of the riser.

Title: Re: Had a bow blow up
Post by: Crooked Stic on July 25, 2019, 02:59:14 PM

Yep looks like the glass lifted there at the front of the sight window.

Title: Re: Had a bow blow up
Post by: Mad Max on July 25, 2019, 03:20:02 PM

Quote from: monterey on July 25, 2019, 02:41:53 PM

Just my SWAG but I think the glue joint failed on the face side of the riser.

x2 at the end of the fade

but looking again at the picture the glass lifted at the arrow rest and sight window. yes?

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 03:34:27 PM

My brother lives in Montana and I'm in Michigan. I'll ask for more pictures

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 04:21:09 PM

Here are more pictures

Title: Re: Had a bow blow up
Post by: Mad Max on July 25, 2019, 04:47:50 PM

but looking again at the picture the glass lifted at the arrow rest and sight window. yes?

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 04:54:28 PM

Not sure! I only have the pictures to go off too :goldtooth:

Title: Re: Had a bow blow up
Post by: Bvas on July 25, 2019, 05:15:00 PM

From what I can tell on my little phone screen......there are two wood lams on the back side and those two lams is where the separation started. I can’t see any tear out on the lam that is still on the riser.

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 05:23:31 PM

Bvas that's what I see too. Maybe a dry glue joint?

Title: Re: Had a bow blow up
Post by: Bvas on July 25, 2019, 05:27:32 PM

What was the core? Hickory?

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 06:27:07 PM

Ash core

Title: Re: Had a bow blow up
Post by: Shredd on July 25, 2019, 08:40:52 PM

My Prognosis...   It's a damn shame...  Build another...  Maybe use maple and no alcohol...

Do you have pics of one of your other bows that is the same model built with the same taper showing brace, unstrung and full draw??  Could be a flaw in your design...  I am not familiar with ash in bows but it has a very open grain which could maybe be an issue...

Title: Re: Had a bow blow up
Post by: Mad Max on July 25, 2019, 08:54:31 PM

Lot's of better core wood for that

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 25, 2019, 09:14:16 PM

I agree but it's the wood I have available

Title: Re: Had a bow blow up
Post by: Flem on July 26, 2019, 12:04:38 AM

I can't imagine the Ash was the problem, unless it was a heavily biased end grain cut. Ash is some seriously strong wood. C'mon, it's the wood of choice for Baseball bats. I know it glues well.
Maybe the bow had a little to much action at the fades, or maybe your Bro dry fired it and was too embarrassed to say so. :dunno:

Title: Re: Had a bow blow up
Post by: Chuck N Stuff on July 26, 2019, 12:11:42 PM

Had a friend accidentally shoot an arrow with no point one time. He was barely shooting 7 GPP to start with and blew one of mine up. No help on something that has weakness!

Title: Re: Had a bow blow up
Post by: Lee Lobbestael on July 27, 2019, 06:14:12 PM

Yeah I think ash is plenty strong and glues well. I used to make self bows from ash.

Title: Re: Had a bow blow up
Post by: bamboo on August 05, 2019, 07:11:47 PM

what kind of glass?----ea-40?