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Main Boards => The Bowyer's Bench => Topic started by: bowhunter15 on July 13, 2016, 10:31:00 AM
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For building a glue-up form, like the two-piece forms used for the air hose method, I often see two pieces of 3/4" plywood laminated together. It's expensive comapered to the other options, Laminated Veneer Lumber, Laminated Strand Lumber (both engineered composite woods, high strength and straightness) or a regular old 2x8 or 10 or 12.
Does anyone have experience with the composite lumber options? And would a pine board be sufficient if it was jointed and planed?
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I've used plywood glued and screwed together and LVL. Both work great.
The only material I had a problem with was particle board. It broke apart in the oven.
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I myself would not skimp on the form. A well designed and made form will make good bows, A bad form will be a total waste.I am in the process of retooling a form, its more work than making the bow from it, but its critical to make it right with the right material.
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All of the forms I've made with LV's have warped,most sooner rather than later even though I use 1 1/2" angle iron on the sides as a stiffener.. I've since gone to MDO (signboard)plywood (2) 3/4" and spacer with the angle iron and have had no issues
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I'll second what PV said . The one and only time I used LVL I had a lot of problems with that form and have since tossed it out and remade it out of Baltic Birch that I glued and screwed together.
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I have only used Cabinet grade Birch plywood myself. There is a Cabinet shop down the road from my house,I usually buy 3/4" from them..But I bought a sheet of 1/2" from Lowes once too. I glue the sheets together on a perfectly flat surface with tite bond II glue and use a bunch of 1 1/4" wood screws. my oldest form was built June of 2009 and its still straight.
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Looks like plywood it is!
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look into laminated scaffolding planks-
-one more thing-tite bond can be an issue at the temperatures we cure at
http://www.kennisonforest.com/products/sure-lam-lvl/
very stiff and uniform
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The titebond II shouldnt work at the 160 degree temps. I put a lot of 1 1/4" wood screws into the form, I think thats what really holds the form together. Mr Bingham used wood glue and screws in his how to build a bow videos so thats what I used to build my first form in 2009..and all the other forms since then, I think the screws are the key to keeping everything in place.
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without doubt Robert!!--my oldest form is tite bond and many many screws!!
I've been using urethane glue [gorilla] on forms it doesn't seem to move
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i concur- i use 1/2" ply and lots of screws- and i run the screws from both sides- on about 4" squares on one side- and then 4" squares on the other side- placed alternately- so thats about a screw every 2" or so- never had an issue!
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I've been using Unibond 800 which cures at pretty reasonable temperatures, but screws seem like a pretty good step to ensure longevity.
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Originally posted by fujimo:
i concur- i use 1/2" ply and lots of screws- and i run the screws from both sides- on about 4" squares on one side- and then 4" squares on the other side- placed alternately- so thats about a screw every 2" or so- never had an issue!
Yep, and mark out your bow profile on both sides before you "screw it up" . Then you don't have screw paths in form face after you rout it.
Don't ask how I found out! LOL
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absolutely spot on kenny- i ran the screws in for my first form. smartened up a bit after that- not much, but just a bit! :)
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I might have a screw "worm hole" on one of my forms too...
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Originally posted by Robertfishes:
The titebond II shouldnt work at the 160 degree temps. I put a lot of 1 1/4" wood screws into the form, I think thats what really holds the form together. Mr Bingham used wood glue and screws in his how to build a bow videos so thats what I used to build my first form in 2009..and all the other forms since then, I think the screws are the key to keeping everything in place.
X 2
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I took a trip to Menards and picked out a nice, straight 3/4"x2'x8' ACX plywood. They couldn't cut there, so I'll have to use a table saw to turn into two 1'x5's and laminate, joint, route profile, and screw together.
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(http://i83.photobucket.com/albums/j308/teenathlete3030/IMG_20160804_113233_zpszzxwaff4.jpg) (http://s83.photobucket.com/user/teenathlete3030/media/IMG_20160804_113233_zpszzxwaff4.jpg.html)
Heres the form all routed to the template. Now I just need to reinforce with screws.