Author Topic: Lamination problems (Read 2321 times)

talkingcabbage · « **on:** February 18, 2009, 10:44:00 AM »

So I've glued up a couple of limbs for a take down recurve, and immediately ran into problems. I really don't understand why. Here's the pics

I had the glue gooped on pretty thick cuz I didn't want any air bubbles. What I'm hoping is that you're gonna tell me that these will in no way affect the performance of the bow. What I know you'll say is to grind off the fiberglass and glue on another piece, or start over.

Someone tell me why these happened. I know it's not the form. If it were any smoother, it'd be glass. I know it's not the clamps. These lams were so tight to the form. I'm not an idiot when it comes to building things, but I can't understand why, when I have a ton of glue squeezing out, why I'd have air bubbles like this.

I should mention these are only on what will be the belly of the limbs. The back of the limbs (the part facing away from the shooter) is fine.

Maybe I should stick with wood bows. They're so much easier!

Joe

Buckeyehunter · « **Reply #1 on:** February 18, 2009, 07:00:00 PM »

I'm not a laminate bowyer but could it be oils in the wood. A lot of tropical woods benifit from degreasing prior to glue up.

PV · « **Reply #2 on:** February 18, 2009, 07:19:00 PM »

Was it from the same piece of glass? The pic's are dark on my computer so I'm guessing. It could be the glass rather than air bubbles.Dark wood shows everything.The ones I can see in the top pic probaby won't be in the finished limb.

kennym · « **Reply #3 on:** February 18, 2009, 07:56:00 PM »

It sort of looks like air to me.Most glass issues I've had were long streaks. A couple ?s
1.. What kind of clamp system did you use?

2..If air hose,did it lose pressure?

3.. Did you use a pressure strip?

4..Was everything fairly warm,lams,glass,and glue?

5.. are they only in the curve?

Apex Predator · « **Reply #4 on:** February 18, 2009, 09:42:00 PM »

The photo seems to show something on the surface only. Are you sure that is under the glass?

Pennsyltuckey pete · « **Reply #5 on:** February 18, 2009, 10:03:00 PM »

It looks like air to me.Tough to see for sure. It could be the start of problems in the future. I have the same look on the first glass bow that I made 4 years ago. it is still shooting.

pete

talkingcabbage · « **Reply #6 on:** February 18, 2009, 10:53:00 PM »

Kenny,

These are air bubbles. I did not warm the glue up. It was just at room temperature, which in my house is about 65 degrees. Should I have warmed it up in the hot box first? I did "degrease" the wood first with alcohol, so I'm fairly sure it's not because of oils in the wood (although I could always be wrong!)

Sorry about the quality of the photos. It is under the glass, although there is some tape residue on the surface.

So my main questions is, what are the chances of getting away with this on these limbs. I'm shooting for 45#, if that makes a difference. If I can't get away with it, Kenny, I need another 72" .040 thick strip of clear glass coming my way.

Thanks guys

kennym · « **Reply #7 on:** February 18, 2009, 11:05:00 PM »

65-70 degrees works pretty well for me. What kind of alcohol? rubbing alcohol has oils in it to keep from drying skin out,so its not good.
I have heard both ways on prepping lams,some say acetone,some say it brings more oil to the surface.
I built a bocote(notoriously oily) bow a few years back,I scrubbed with a wire brush and blew off with clean air,and it is still going.

As far as getting away with it,clean the tape residue off and assess the problem again.

If you are thinkin of adding another pc of glass over them,the possible delam will still be there,just deeper in the limb.JMHO

If mine,I would finish the bow,carefully shoot it a bit and watch for any increase in dry spots. Very carefully,safety glasses and all!!

How many colored glass bows have the same deal?

Just be really careful,whatever you do,it is not worth losing an eye over.

talkingcabbage · « **Reply #8 on:** February 19, 2009, 12:40:00 PM »

actually, I was thinking of grinding off that back layer of glass and gluing on a new piece. Trying to do it better the second time, I guess. So you think I'd be okay proceeding from here? I guess I could always finish it out, and if it gets worse, grind off the glass later, right?

kennym · « **Reply #9 on:** February 19, 2009, 09:27:00 PM »

If it were mine,I'd finish it on out,shoot CA anywhere I could on limb edges where you cut thru an air pocket, and try it.

Disclaimer: Some of the stuff I do doesn't work!!

Grinding the glass off without ruining the core lams would be very tricky I would think.

Come on guys ,help me out here!! Do you all think this is safe to proceed with?

talkingcabbage · « **Reply #10 on:** February 19, 2009, 09:32:00 PM »

I had thought about drilling some small holes through the glass layer and injecting them with CA glue.

by the way, some of the stuff I do doesn't work either.

I think I'll try the injection method and let ya'll know how it works. worst case is that it will start to delam and I'll have to grind it off and glue on another. I'm pretty confident I can do that okay without ruining the wood. You can say I'm used to cobbling things every once in a while!

I really need to stick to wood bows....

mq32pa · « **Reply #11 on:** February 19, 2009, 09:44:00 PM »

I'd have to agree with Kenny. I've made a couple not as much as yours but used CA before finish(didn't help much) but it is still a shooter.

bjansen · « **Reply #12 on:** February 19, 2009, 09:47:00 PM »

I would do just as Kenny, finish it out, cram CA glue in anywhere you can on the sides and see what happens...shoot it many times with proper safety gear and see how it goes..worst case scenerio you make new limbs...

i think it would be hard to grind that lam off and more likely result in ruined bow...plus another 20 bucks lost on new glass

I would continue..I have a couple i made that turned out like this as well and i still shoot them today...i wont give them to others of course...but i will keep them.

The ways that i no longer get air bubbles are as follows:

1. Heat up the glue a bit (even mixing it in front of a heater works good is a colder garage)
2. Clean e/t twice with Acetone
3. Use plenty of glue (smoothon)...Spread it on both surfaces of e/t you are glueing up. Then roll it with something (i.e. a wallpaper roller, epoxy roller, or something to get a nice even smooth coat).
3. Assemble and clamp, lightly then adjust, then more preasure until you get to 60PSI on the hose (or fairly snug on the clamps....and if using clamps use plenty of preasure strips, rubber strips, scrap lams, etc to even out that preasure).

Last time i did these steps i had zero air bubbles..and was elated at that was the first time i had such success.

best of luck

kennym · « **Reply #13 on:** February 19, 2009, 10:32:00 PM »

Good points guys, also I like to never lower the pressure,even when I check the air pressure,I give it one last little shot for what the tire gauge let out. Then check for leaks,loss of air pressure spells disaster!

Another thing about clamps and cold glue,as the glue squeezes out,there is less pressure on the clamp.

TNstickn · « **Reply #14 on:** February 20, 2009, 12:13:00 AM »

What Kennys been sayin is good stuff. Along with the clamps loosin preasure with squeeze out, the glue will get more runny as it warms adding to the lower clamp preasure. Could have caused a "dry spot". I would finish it out, If a air bubble runs to the edge, fill it with CA, and be careful test shootin. It would be next to impossible to get that glass off without damaging the lam.

droptine59 · « **Reply #15 on:** February 20, 2009, 07:11:00 AM »

I agree with all points. too much pressure, too much heat are enemies no matter what. Another notion is an uneven form or uneven pressure. a few thousanths of an inch with uneven pressure will give one fits...However, from looking at the pics...in my experience, it has mainely been enough glue.. I mean you can never get enough on in glue up. If it looks like a gooey mess, then it needs more

Glenn Newell · « **Reply #16 on:** February 20, 2009, 02:23:00 PM »

When I first started making laminated bows I used G clamps and had air bubbles under the glass like that on the first couple I made. As the glue heats up in the oven the clamps loose pressure, you have to check them for prussure while the bow is in the oven. After I went to an air hose I haven't had a problem since. If you are using clamps you need as already suggested pressure strips and rubber to get the best results.
I never had one of the bows fail with air bubbles under the glass...Glenn...

talkingcabbage · « **Reply #17 on:** February 20, 2009, 07:27:00 PM »

That's good to know Glenn. It seems as though a few bubbles won't matter too much as long as I go slow. It just makes the limbs look shabby. Ah well, another lesson learned!

Thanks for all the input guys. I'll post pics later.

sulphur · « **Reply #18 on:** February 22, 2009, 07:46:00 AM »

thanks for posting this question cabbage. It helps answer some ??? i've been having.

kennym · « **Reply #19 on:** February 23, 2009, 11:29:00 PM »

Hows it comin Joe?

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