Author Topic: Laying out the bow shape...  (Read 557 times)

Online Roy from Pa

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Laying out the bow shape...
« on: January 16, 2010, 01:20:00 AM »
When I first got into making Bows from Osage wood some 8 years ago. I followed Dean Torges BBO method, bought his DVD, Hunting The Osage Bow.

I have made some nice, Boo backed Bow's with deflex and reflex. I even pushed it a bit and cut 1/8th thick kerfs 8 inches down the end's of the limb tips and glued in 1/8th shim's to make the tips have even more reflex on the end of the limbs. Made for some sexy looking bow's. And they shoot great. The extra reflex in the tip's did give me fit's while tillering those Bow's.

In Dean's DVD, he mentioned to cut 1/8th inch wider outside your lines from mid limb to the fades. To give the area from the riser to midlimb more strength. I veered away from that because I like a Bow that taper's even from flares to tips. That caused me trouble because now not cutting that area wider, made my limb tip's stiffer.

Now I want to try my first Red Oak Board Bow. It will not be backed with anything. I am shooting for a Bow around 45 pounds at 27 and 3/4 draw length. I figure I will make it about 66 inches long, as I don't really like real long Bow's:) And I don't really like real wide Bow's either:)

I also do not like Bow's that take set. It just bother's the heck out of me. I like to add reflex to a Bow, then after tillering it, end up with a Bow with maybe an inch of reflex, or a straight limb Bow.

So I got me two nice sister billets of Red Oak, 1/2 X 2.5 X 36 long. They are 1/4 sawn, and really nice straight grain the entire length of both billets. I will Z-splice them together.

Now my questions are, can I lay this Bow out to have an even taper from the end of the riser to the limb tip's? Should I run the Bow across the jointer to give a slight taper from the end of the risers to the limb tip's? And can I induce some reflex into the limb tip's, with heat? How does Red Oak respond to heat?  

Here is what I thought about, I use clamps,and a form with a center post block, mid limb blocks, and limb tip blocks, to get the shape I want when making those BBO Bow's. So I was wondering if I clamp this non backed Bow into my form, and put 6 inch limb tip post's under it, then put it in my heat box at 143 degrees for a few hours, would that heat and form yield me some reflex when I take it out of the heat box? And will the 143 degrees dry out the wood too much?

Ya I know, 50 questions:) But I am having fun making different Bow's.  
Thanks, Roy

Offline Art B

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Re: Laying out the bow shape...
« Reply #1 on: January 16, 2010, 08:40:00 AM »
Common sence tells me to not use a stressful design for unbacked board bows Roy. But then again I don't make board bows, so you'll need to wait on the board bow experts for more info than that.

But tapering is tapering. An 1 1/2" limb width  pyramid design will still require some belly tapering. A 5/8" limb thickness just outside the fades tapered to 1/2" thickness at the tips will get you started. And adjust from there.

I do know that red oak is hard to bend. Maybe reduce you limb tips to close to finish dimensions but leave full width and go for a shallow bend with steam.........ART

Online Roy from Pa

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Re: Laying out the bow shape...
« Reply #2 on: January 16, 2010, 09:28:00 AM »
Thanks Art. This board bow will be new to me and I figured this is the place to ask.

Online Pat B

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Re: Laying out the bow shape...
« Reply #3 on: January 16, 2010, 10:31:00 AM »
Roy, for the design and length you are talking about I think I would have it 2.5" at the fades with a straight taper to the tips or I would go    1 3/4" to 2" at the fades and out most of the limb, tapering the last 8" or so to 1/2" tips. As you tiller either of these bows, if they seem to be getting to thin begin removing some of the width as you tiller(tiller from the sides not belly).
  Trying to compare red oak to osage is like oranges to apples. Each wood has it's own strengths and weaknesses and the design should highlight the strengths of each wood.
Make the most of all that comes and the least of all that goes!
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Offline George Tsoukalas

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Re: Laying out the bow shape...
« Reply #4 on: January 16, 2010, 04:19:00 PM »
If you put in 3 in of reflex, tiller out the bow, and have 1 inch of reflex left you still have 2 inches of set.  Like judgement day set is inevitable. If you do what you want to do with adding reflex, Roy, with the red oak be sure you take the time to choose flawless straight grained stock. jawge

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