Primitive Archer
Main Discussion Area => Bows => Topic started by: lesken2011 on December 08, 2012, 08:58:29 pm
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I finally got around to making a hot box since it got too cold to glue on backings overnight in my garage/shop (it is not heated) Trying to conserve on space and get as much as I could from one 4' X 8' sheet of styrofoam insulation, I made the box 1' deep by 18" high. I don't really intend to do elaborate glue-ups, just backings, mainly, but I would like to put a little reflex in them to take out the inch or so set I have wound up with lately from straight glue ups. I make most of my bows 66" t2t or 60" t2t depending on whether they have a bendy handle or not. The two times I tried to add some reflex about 6"from the tips, the bows failed due to glue starvation at the point I clamped them down. I really loved the way the unstrung profile was on those, though. What I am trying to do now is avoid the mistakes of the past. As you can see in the photo below, I have 4" blocks at the end with a clamp in the middle which I figured I would pull to about 2 or 3 inches of reflex. That way I figured I would wind up with a dead flat unstrung profile or a slight reflex. My question is this. When I put the clamp in the middle of the bow, it looks like all the reflex is in the handle area rather than a smooth bend. The next photo shows 2 clamps farther apart which looks a little better, but still not what I am looking for. Can someone give me some feedback from their experience with similar set ups?
(http://www.traditionalbowman.com/hwdphotos/uploads/62/2/0otnuscid7oxnr.jpg)
With 2 clamps...
(http://www.traditionalbowman.com/hwdphotos/uploads/62/2/8wkz8zzbc45agu.jpg)
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I would leave the center piece in only. Unless your going after an R/D profile you dont need any other uprights in there. And I would push it all the way down. Give it the full 4" or so. I glue my handles on first, then clamp the center down. It forces some of the relfex out further in the limbs. No matter what way you chose, your on the right track Kenny.
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One clamp in center.
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More clamps.
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It will also help to have a better thickness taper in your lams so you get a more even bend and arc into the working limbs where you want it when you clamp it down at center..
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Thanks, Chris, Roy, & Blackhawk! For some reason my arc didn't seem even with one clamp in the middle. The two bows I had fail were both bamboo backed, so I have never made a successful bamboo backed bow. My next glue up is a 60" bamboo backed massuranduba, ipe, or osage with a bendy handle so I won't be gluing a handle piece on this one. I generally use a pyramid taper, so very little thickness taper is necessary, but you (Blackhawk) are saying I should taper the bow to at least the floor tiller stage before I do the glue up to keep the circular arc during the glue up?
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R/D glue up. Remember to pad the boo so your clamps don't indent it, or it will splinter up on you when tillering. I use short pieces of boo for that, works great.
(http://i47.photobucket.com/albums/f165/ROY-CHRIS/IMG_7262.jpg)
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Kenny ...lay out the boo to final front profile dimensions,except leave a tad bit of extra width at the tips,and cut it out to literally just outside your pencil lines so that the boo backing is pretty much at final dimensions. Taper your bellys front profile into a pyramid shape,but just a lil wider than the boo backing is,and make the 6" of the bellys center thicker and parallel,this way the center will be stiffer and you will have a nicer arc when you clamp it in the center. Make sense? I'm in the process of doing another bendy boo backed bow myself(although not pyramid shaped),and that's what I do to get a nice even arc when clamped during glue up.
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Thanks, Roy & Blackhawk. In the past I have strapped my core piece and backer down to a beam with rubber straps. I plan on wrapping the backer and core wood together with rubber bands (inner tubes) the way Half Eye does it, and then putting it on the "form". Is that how you and Pearly do it, Blackhawk? I know Roy uses clamps.
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I have done it both ways Kenny,and both will work if done correctly. I think the clamps and pressures strips work a lil better if doing more than moderate shaping IMHO.
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Just a basic 3 or 4 inch refex, for now. My box may not be wide enough for the clamps so I will try the rubber straps, for now. I'll keep ya'll posted. Thanks for the help!!
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I'm not so sure about the advice Roy's giving you. Never trust anyone with a shop that clean! ;)
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LMAO
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Sorry for the aside, ...but Roy, is that a Holly Hobbie cut out you have lying on her back in behind your bow bench in your otherwise pristine shop???
BTW - Thanx for all the Hotbox and glue-up tips. These are on my Bowyer's bucket list...
OneBow
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I'm starting to realize that I have far too few clamps. ;D
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LOL, that's my Sisters outdoor x-mas decoration. She had a broken arm so I gave her a new arm:)
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I used to use those movable spacer methods but I got inconsistent results. Now I use a an oak guide rail and then I cut pine curve sections that free flaot. the curvature is exactly the same each time and if the wood softend in the hot box it can only go to match the form. But my parts are movable and interchangeable so I can adjust length and curvature.
I'll try to get a pic up .