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Jamie

Senior Member
5,690
177
Ohio
I'm glad to have gotten motivated to build a form for gluing up bamboo backed osage bow blanks. for nearly 20 years I've been using an adjustable form with C-clamps and small bar clamps, to the tune of 35+ to glue up a bow. is kind of a hassle, very difficult to carry into the warm house so glue will dry this time of year, easy to accidentally move tips out of alignment or twist a limb while tightening all those clamps. for as simple and inexpensive as it was to make, it sure has shaped a bunch of bows and done a fine job. best part about adjustable form is that it is adjustable, permitting freedom to manipulate the amount of reflex and deflex, freedom to glue up working and static recurves, D/R flatbows, or simple straight limbed flatbows and longbows.

I don't experiment with designs as much as I used to since I arrived at a D/R profile that provides me everything I want in a hunting bow. smooth, stable, quiet, powerful. building this form was much more complicated than I had planned, and more work than I figured, too. since this was my first attempt at making such a thing, I spent a lot longer solving problems along the way than I'll need to next time. I did a couple of dry runs with actual stock to make sure all was working/fitting properly and to time myself. Urac 185 has an open working time of about 30 minutes, so there is not time to waste, and it is best to know exactly what you are doing, have everything in order before you mix up the glue. I discovered a couple of problems and fixed them. did one more dry run just to rehearse the routine then mixed up glue and did it for real. fingers crossed.

first bow on new form 2-26-2014.jpg

the virtues of a form like this are better glue lines due to the even clamp pressure distribution, no chance to torque a limb out of alignment while hand tightening 35 clamps and very little chance to move the tips out of alignment if you are mindful of what you are doing. once bow is clamped up it takes about 2 seconds to inflate hose to 60 psi. this is the type of form nearly all fiberglass laminated bow makers use.

I got the piece of LVL from a trash pile at Carter Lumber last summer for free. the hose, plugs and hardware cost a little over $100 to my door from Bingham's Archery. had to buy a router and flush trim bit for it, too. has been an interesting project. find out tomorrow if it was worth all the trouble.
 

Jamie

Senior Member
5,690
177
Ohio
totally worth the trouble. glue lines considerably better with air hose form. I'm surprised how much better, actually.

limb on top in pic is from air hose clamping, limb on bottom from manual clamping.

air hose vs. manual clamps.jpg

the glue joints I've gotten with manual clamping are still pretty good considering I have to taper the bamboo thickness by hand. is not possible to do it properly any other way. I've never had a glue joint failure, either. the old way is more than adequate. thinner glue lines is simply a matter of pride. :smile: