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Main Boards => The Bowyer's Bench => Topic started by: Elison on October 15, 2016, 09:28:00 PM

Title: Delamination in recurve
Post by: Elison on October 15, 2016, 09:28:00 PM

Hi guys!

I'm trying to make a recurve bow using a bingham plan, but when I started to bend the wood and the glass started to delaminate in 2 points:

  (http://i655.photobucket.com/albums/uu275/iam_malcolm1/Mobile%20Uploads/20161015_164505.jpg) (http://s655.photobucket.com/user/iam_malcolm1/media/Mobile%20Uploads/20161015_164505.jpg.html)

  (http://i655.photobucket.com/albums/uu275/iam_malcolm1/Mobile%20Uploads/20161015_164455.jpg) (http://s655.photobucket.com/user/iam_malcolm1/media/Mobile%20Uploads/20161015_164455.jpg.html)

  (http://i655.photobucket.com/albums/uu275/iam_malcolm1/Mobile%20Uploads/20161015_164121.jpg) (http://s655.photobucket.com/user/iam_malcolm1/media/Mobile%20Uploads/20161015_164121.jpg.html)

  (http://i655.photobucket.com/albums/uu275/iam_malcolm1/Mobile%20Uploads/20161015_164101.jpg) (http://s655.photobucket.com/user/iam_malcolm1/media/Mobile%20Uploads/20161015_164101.jpg.html)

Any idea in how I can fix it?     :confused:  

Thanks

Title: Re: Delamination in recurve
Post by: Wolftrail on October 15, 2016, 11:18:00 PM

Not sure but maybe bad glue, prep surfaces rougher, large gaps perhaps....    :confused:
Not sure about fixng it,  sure others will chime in.

Title: Re: Delamination in recurve
Post by: mikkekeswick on October 16, 2016, 02:59:00 AM

You can't fix it now i'm afraid....time to start again.

Title: Re: Delamination in recurve
Post by: JamesV on October 16, 2016, 06:50:00 AM

Option 1: If the fades are not damaged you can strip the riser and rebuild the bow. Be sure to wipe down the riser, lams and glass with acetone and wear gloves to do the glue-up.

Option 2: The core does not appear to be damaged, You might try to re-glue the de-lam. Nothing lost if it doesn't hold. If you can work some epoxy all the way in at the de-lam, Super glue will not hold. I would try to stress the limb to open the crack and use a hacksaw blade (with the teeth ground off) to force the epoxy into the crack then clamp it. If you warm the epoxy it will flow better.

Good Luck

James

Title: Re: Delamination in recurve
Post by: Pago on October 16, 2016, 03:42:00 PM

You can thin smooth on or other epoxy with 95% pure isopropyl but, no offense intended the layup looks sketchy to me.  Possibly too much or not enough pressure in that area on the layup.

Title: Re: Delamination in recurve
Post by: kennym on October 16, 2016, 03:47:00 PM

I'm not seeing much damage to wood, so may be an adhesion prob. What kind of glue and what type of form (air or bands)?

Title: Re: Delamination in recurve
Post by: mikkekeswick on October 17, 2016, 03:14:00 AM

Trouble is those surfaces have already had glue on them. All the pores are now filled, the bond would be poor at best if you just tried to get some glue in there and clamp it up again.
Something caused the glue to fail, the reasons are too many and varied for anyone to know from looking at those pictures.
Who wants a bow that is a ticking time bomb....!

Title: Re: Delamination in recurve
Post by: Krasus on October 17, 2016, 09:28:00 PM

Fade looks like it has a square end rather then tapering to nothing

Title: Re: Delamination in recurve
Post by: Roy from Pa on October 18, 2016, 05:33:00 AM

Yes it is square, good observation.

Title: Re: Delamination in recurve
Post by: Elison on October 20, 2016, 09:16:00 AM

The wood don't broke when delaminate.
So, I tried to glues it again, thinning the epoxy with a heat gun to fill all the gaps.  
It seems to be ok in this part.  BUT, the limb delaminate in the tips too.  D=

Causes for bad epoxy.  

Let's see if this bow will turn a bow or a firewood.