Author Topic: glue issues. help please (Read 989 times)

Krasus · « **on:** January 31, 2015, 01:46:00 AM »

Just had my second bow explode due to a glue void in my limb. Only built 3 bows so far. I just got some aluminum strips for my clamp ups. My trilam looks good that I just glued up using them with my claps. Nice smooth curves. No kinking.

It is just my inexperienced with my glue ups? Pointers and tips would be great.

Thanks gang

fujimo · « **Reply #1 on:** January 31, 2015, 02:29:00 AM »

what glue are you using, white glues need smooth, perfect mating surfaces- unibond and epoxies are gap fillers and like the surfaces to be roughed up.
neither glue likes over clamping- which leads to glue starvation.
any pics etc, and of your clamping system will help folks give an opinion- sorry to hear that your bow failed
keep on keeping on!

Pat B · « **Reply #2 on:** January 31, 2015, 08:31:00 AM »

Will you post pics of the break. It might be other than the glue.

Krasus · « **Reply #3 on:** January 31, 2015, 11:14:00 AM »

I'm using smooth on ea40. I rough up all surfaces and then I cook it in my heat box at 170 f for 8 hours. Then allow to cool over night.

No pics yet. Still trying to figure out how to post them.

fujimo · « **Reply #4 on:** January 31, 2015, 12:34:00 PM »

well sounds like you are doing everything right. the only concern now is possibly glue starved joints. but like pat says pics will help heaps.
i am not saying clamps dont work- a lot of folk get them to work extremely well, in fact. i just dont think i am smart enough to get them to work- too many variables for me- :D thats why i rather use the airhose- or rubber bands- but just whatever you can make work is good!!

Shootum Straight · « **Reply #5 on:** January 31, 2015, 01:21:00 PM »

How old is your glue?

kennym · « **Reply #6 on:** January 31, 2015, 02:06:00 PM »

The thing I don't like about clamps is as the glue squeezes out, the clamp pressure decreases.

When doing a riser, I tighten slowly and take my time, checking several times before it goes in the hot box. Still the clamps aren't as tight when you are done....

breazyears · « **Reply #7 on:** January 31, 2015, 02:10:00 PM »

Never liked using clamps.
If your not using the fire hose method. I would recommend using tire tubes. I have always had problems when using clamps... even pressure is always my problem. That being said. I do use them around the riser only.
Make sure you butter both mating surfaces, and have no voids. Once you have brought two mating surfaces together, don't pull them apart. Try your best to get them where they need to be the first time.
These are just a few things that I do. Hope it helps a little.

Shootum Straight · « **Reply #8 on:** January 31, 2015, 02:31:00 PM »

How old is your glue?

Krasus · « **Reply #9 on:** January 31, 2015, 08:36:00 PM »

Glue is maybe 3 months old. I'm super careful when mixing my part a with part b. I use separate spoons and a separate mixing spoon.

The clamps I use are just 2 inch spring clamps (nice even pressure). I do 2 clamps every 3 inches. I also use 2 strips of 1/8"aluminium (on top and one below) my lams to distribute the clamping pressure evenly.

fujimo · « **Reply #10 on:** January 31, 2015, 09:33:00 PM »

sounds good!!???!!
do you have a photobucket account- set one up- its pretty easy- also can try imagelinkey

Wolftrail · « **Reply #11 on:** January 31, 2015, 09:55:00 PM »

I have been quite lucky even using TT3 with some slight not so good mating surfaces. I rough all pieces with 50grit and use a vacuum cleaner to clean the mating surfaces. I believe this is best becasue it gets all the microscopic particles deep down in the wood fiber.

Take it for what its worth but I have not had a glue failure since...! Bad design Yes......Bad tiller Yes...! Overstressed Yes..!

Krasus · « **Reply #12 on:** January 31, 2015, 10:02:00 PM »

Oh. . I never even thought of that. Good one thanks

mikkekeswick · « **Reply #13 on:** February 01, 2015, 02:41:00 AM »

How are you preparing the lams?

Krasus · « **Reply #14 on:** February 01, 2015, 08:47:00 PM »

I rough all of them using a pull scrapper I modified with a section of hacksaw blade. Works great to rough up the wood.

AkDan · « **Reply #15 on:** February 04, 2015, 08:03:00 AM »

Dumb idea but you guys who mentioned not liking clamps and in-consistent torque issues. Couldn't you rig a special socket (couple slots to accept the clamp handle) on a torque wrench to get even pressures at the clamps at least?

Roy from Pa · « **Reply #16 on:** February 04, 2015, 08:30:00 AM »

I don't have a lot of faith in spring clamps.
I've also read where a hack saw blade is not the proper tool to rough up the surface. I use a toothing plane on all surfaces that will be glued together. Then blow the surfaces off with an air hose, then wipe them down with denatured alcohol. I apply a nice coat of glue on both surfaces with a paint brush. I use unibond800, so a paint brush would be tough with smooth on. I pad the back and belly of the bow so my clamps don't indent the surfaces. I place a clamp every two inches, alternating their position from side to side. I snug down the clamp and then go about another 1/2 turn.

snapper1d · « **Reply #17 on:** February 04, 2015, 09:02:00 AM »

Roy you are right about the hacksaw blade.Rip up your wood to a bunch of broken splinters and thats what you have holding your glue just broken splinters not solid wood.Why attach to wood that is already broken up?

Krasus · « **Reply #18 on:** February 05, 2015, 09:26:00 AM »

I'll give the toothing plane a try. I don't use c clamps cause once you heat them they loosen.

traditional1970 · « **Reply #19 on:** February 07, 2015, 05:24:00 PM »

cut your oven time down. I only go 4 hours

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Author Topic: glue issues. help please (Read 989 times)

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