shrink wrap for composite clamps?

[deermaster]

i saw in a PA mag (april/may) in a r/d glue up article that he was using saran wrap or a shrink wrap to clamp the backing to the core.  i baught a roll at home depot and was wondering if it is strong enough to get a good glue joint or if a rubber stretch wrap like inner tubes should be used on top of it? thanks for any info!

[Justin Snyder]

I use saran wrap, but it is to keep the mess down. I still use clamps.  Justin

[bowstick]

My dad was the one who posted that article.  It is true... You can use 120 guage or thicker stretch film for just clamps.  YOu must go over the same spot 3 or 4 times and start from the handle and stretch as hard as you can without breaking the wrap... This method only works with wood to wood, it does not work with fiberglass composite bows. 

Justin

[tom sawyer]

My guess is, if you wrap it tight then it would work.  You don't need a tight clamping with URAC or resorcinol, in fact you can starve a glue joint if you do.  You do want good contact between the surfaces though, to minimize large gaps.  URAC fills gaps up to 1/16" I think.  You might need clamps if you are forcing the glueup into a particular shape such as a R/D.

I assume you are using a catalyzed glue and not something that needs to air dry.  I don't know if covering a bow glued with Titebond would work, and you do need more clapming pressure for those types of glue I think.

[Justin Snyder]

The biggest problem I forsee with the whole concept is,  you have to hold the pieces perfect while wrapping.  While wrapping the two pieces will slide back and forth.  This will work the glue out of the sides of the joint and potentially starve the joint.  Another problem is that with wood and a water based glue, the thin wood tends to roll up on the edges when it absorbs the water.  This meathod would allow no practical means of fixing that.  Lets just say the cons far outweigh the pros.  Justin

[bowstick]

The bigest problem is actually has the easiest solution... To keep the parts still... just use a table vice and a few spring clamps to start.  You wrap the bow first, then put it in the block mold and Walla!

The stretch wrap work great even on Reflex deflex bows.   Just use 5" wide and 120 guage or thicker and its better than bike tubes



And notice you only need 2 c-clamps for the whole process.  This system simplified our bow making and nearly cut our production more than in half. 

or if you just want to use simple spring clamps...


The end result is all the same, a nice RD stave ready to turn into a bow


I've only bowgrip 100 on this process... which is a 2 part epoxy which also is a gap filling glue.  Doesnt require heat to cure but takes near 48 hours to get to full strength without heat and only about 2-4 hours with heat.     

I am going to do an experiment tommorow with just tightbond... see how well it holds it shape. i will post pics for anybody interested.

[kerbinator]

I have used stretch wrap with bow grip and it worked really well. But when I tried it with Tite Bond III it was like putting the glue back in the bottle it just didn't seem to cure out as well. I too got this Idea from the PA article.

[Pat B]

The water from water based glues has to go somewhere and if you prevent it from evaporating because of the shrink wrap it will just go into the wood or not cure at all. With other types of glue like Urac or the epoxies the shrink wrap should work fine. My problem with it is that there is a lot of non-biodegradable material left over to dispose of.     Pat

[Justin Snyder]

My problem with it is that there is a lot of non-biodegradable material left over to dispose of.     Pat

This can be a chore to clean up.  If you wrap it tight, it will force the glue that does come out the sides onto the back and belly of the bow.  That just makes the clean up even worse.  Justin

[bowstick]

#1  Yes, there is a lot of non-bio degradable material afterwards.  The good thing is that when its time to remove the wrap, you can simply use a razor on the belly edge of the bow to split open the "Shell" peel away the wrap in 2-3 large sections... occasionally in one shot.  And then throw it in the plastic recycle bin   Once you have the system down its very simple

#2  Re-guardless of what glue I use I normally toss it in the heat box for a little bit... I didn't get around to doing the titebond RD bow today, but once I do, I am going to throw it in the heat box for 2 hours at 160 degrees... hopefully it will evaporate the water in the water based glue ... but again, this is all Research and development at this point in time.  I'm confident it can be done with the correct steps taken.

#3 When you wrap tight it does get pressed onto the back and belly of the bow, this is true.  If you are using a flat backing such as hickory or fiberglass, you can simply put masking tape down first.  Also, put the masking tape on the belly of the bow... then afterwards just peel the tape off and it is clean as can be.  Bamboo can be trickier.  Normally we just let it get on the back of the bow and then use a pocket knife to scrape the glue off... if you haven't sanded through the rhind yet, the glue will pop right off in large chunks... then just hand sand with 150 grit.   But I found the real trick but I just don't do it each time.  Before you wrap it up, use PAM Spray or any oil on the back of the bamboo, just the back... Then the glue really has nothing to stick to.  Its a great trick and really works.

Hope this info can be of help to anyone.

Justin

[Pat B]

TBII and TBIII break down at 150deg(F). I called them to find out how to remove a backing that I had used TBIII and the guy told me to heat it to 150deg and it would come apart...and it did.   Pat

[bowstick]

Thanks for the info about the tightbond breaking down at higher temps... I wonder though, is it in some strange way like an epoxy glue... where as you can heat cured epoxy up and soften the glue Line to remove the laminate... but once it cools  it is hard again...

And since I would only be putting the bow in the heat box once... as long as it never gets to 150 degrees again...  it should work, as long as bringing the temperature to 150 degrees as it's drying doesn't ruin the properties of the glue. 

Great info though...  thanks

Justin

[Pat B]

You might want to call their tech number and ask them about its characteristics after heating. I was only concerned with separating a hickory backing strip that had failed across the back(fungi) but the belly wood was still good. Pat