How do you clamp/secure lams?

[Yooper Bowyer]

I am getting ready to glue up a wood backed bow with EA 40, how do you clamp/secure the lams when you do something like this?  How much pressure is needed?  I have inner tubes, but I can assemble a pile of bar clamps from scrap wood and 1/4-20 bolts.  I would like to glue in a few inches of Perry reflex.  I don't have a form, but I have the bow reverse tillered and I will clamp the center to a board and prop up the ends. 

Thanks,

[gutpile]

I just use the squeeze spring clamps... one alternating every 1/2 past the last.. they apply good pressure but won't squeeze out your glue.. I use a big c clamp for the handle area.. in a perry reflex style..pics on my instagram I can not load pics here.. gut

[gutpile]

I'll add I use a small piece of wood under my clamps to spread out pressure and a few c clamps that I use a 1x1 piece of wood too ,to not damage the back. I don't over tighten the c clamps I just run out of spring clamps .. gut

[RyanY]

The amount of pressure really depends on the glue so you should look at the manufacturers recommendation. Clamps will help close gaps but if the mating surfaces are a good fit you don’t necessarily need a ton of pressure for PVA glues like Titebond. Not sure about epoxies, especially since some have good gap filling properties. I use plastic packing wrap for my bows and have gotten great results. I’d like to get my hands in some inner tubes.

[mmattockx]

Clamps will help close gaps but if the mating surfaces are a good fit you don’t necessarily need a ton of pressure for PVA glues like Titebond.

You need to make sure your lams are thick enough to not warp from the moisture in the water based glues. I was doing an experimental lam bow layup with fairly thin lams using TBIII and they cupped horribly from the moisture.

I’d like to get my hands in some inner tubes.

Call around the local bike shops, I got a couple plastic grocery bags full of used tubes from one. They usually collect a pile of tubes with holes in them and throw them away if no one wants them. It's too bad you are across the border, I would mail you half of my pile if you were closer.

DC is a big fan of wrapping with inner tubes, among others on this site. You need a good dry fit that doesn't need much clamping force to close everything up, but aside from that they work great.


Mark

[Pat B]

I've found with inner tube wraps you can't wrap too tight. I wrap the bundle with the inner tubes then put it on a form but in your case just wrap first then clamp the handle and lift the tips on to blocks and let the glue cure.

[Bob Barnes]

I’d like to get my hands in some inner tubes.

I just go to wally world and buy 27" bicycle tubes...cut them in 1/2" pieces for rubber bands or remove the valve stem and cut the length-wise for wrapping bands.

[RyanY]

Thanks guys. My lack of inner tubes is more of an effort issue than a supply issue. There’s a local bike shop I’ll ask at some point. 

[Bob Barnes]

Thanks guys. My lack of inner tubes is more of an effort issue than a supply issue. There’s a local bike shop I’ll ask at some point. 

~ you are far too talented to wait much longer... !
Bob

[Yooper Bowyer]

Ok, how do you keep the tubes from being glued to the wood?

[Will B]

Wrap the blank in Saran plastic wrap after glue up and before wrapping with inner tubes.

[Yooper Bowyer]

Well, I don't know how perfect a perfect glue line is, but I fell pretty good about it, the blank is table sawn and sanded, the backing was machined flat.

@Pat, good to know, I will give it a go. 

[bownarra]

Clamps will help close gaps but if the mating surfaces are a good fit you don’t necessarily need a ton of pressure for PVA glues like Titebond.

You need to make sure your lams are thick enough to not warp from the moisture in the water based glues. I was doing an experimental lam bow layup with fairly thin lams using TBIII and they cupped horribly from the moisture.


No cupping is because of the way you apply the clamping force. If you are using thin lams you need to use a pressure strip.

[bownarra]

Use parcel tape then clingfilm wrap to stop lams moving.

[Tommy D]

The amount of pressure really depends on the glue so you should look at the manufacturers recommendation. Clamps will help close gaps but if the mating surfaces are a good fit you don’t necessarily need a ton of pressure for PVA glues like Titebond. Not sure about epoxies, especially since some have good gap filling properties. I use plastic packing wrap for my bows and have gotten great results. I’d like to get my hands in some inner tubes.

Pat might be right about inner tubes never being able to clamp too tight - but I do know with epoxies in general laminations (eg wooden boat building) that you can make a joint too tight and squeeze out all the glue and have a resin starved joint. There are products such as glass spheres, or very thin copper wire filaments, or some people use monofilament line, to act as “bond-line spacers” to make sure that however much clamping pressure you exert there is space for the epoxy...