Author Topic: Need input on designing a maple/erc lam bow  (Read 1801 times)

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Robert

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Need input on designing a maple/erc lam bow
« on: May 26, 2009, 01:13:32 pm »
Hey guys.

I've been lurking around here for a while, and you guys make some awesome bows.  Thanks in part to this site, I've made a few selfbows from boards and staves that turned out well.  But I want to try a laminated bow for my next project, and I'd like some input on some of the big decisions.

What I have so far:
The bow will be for my sister, who has a 24" draw.  I'm aiming for 30 lbs draw weight.  I'd like to make the back from hard maple, and the belly from eastern red cedar heartwood.  I want it to be kind of a "fancy" bow, with a big pistol-grip handle section and a R/D profile with flipped tips.  I usually tiller my bows so that the inner and mid limbs do more work than the tips, so the front-view profile will probably be somewhat like a (narrower) paddle bow.  I'm fine with making the bow a little longish for its draw-length, maybe 62-64 inches.

My biggest question is how thick should the maple backing be.  I have read that maple is tension-strong while ERC is compression-strong, but ERC is much lighter and seems more brittle, so I am thinking that the maple backing will have to be quite thin to avoid overpowering the belly.  Any ideas for a starting point?  Also, with the bow being long and light, I want to keep the limbs narrower so that my lams will be of a manageable thickness.  I could use some suggestions for an ideal width (at the paddle flares).

Beyond that, any advice about this particular combination of woods (can't recall ever seeing one posted before) or glue-ups, tillering, etc, would be great.

Thanks- Robert 


Offline knightd

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Re: Need input on designing a maple/erc lam bow
« Reply #1 on: May 26, 2009, 01:31:03 pm »
1/8" on the maple backing is what I would start with.. 1 1/2" to 1 3/4" at the fades 62" NTN.. JMO

Robert

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Re: Need input on designing a maple/erc lam bow
« Reply #2 on: May 27, 2009, 10:24:51 am »
thanks knightd.  -Rob

Offline snedeker

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Re: Need input on designing a maple/erc lam bow
« Reply #3 on: May 29, 2009, 12:30:55 pm »
Haven't done it, but I would think maple would be super on ERC

Dave

Offline adb

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Re: Need input on designing a maple/erc lam bow
« Reply #4 on: May 29, 2009, 04:20:15 pm »
I've done numerous maple backed osage narrow profile ELBs up to 55#, and I've used 3/16" thickness for backings. I use 1/8" hickory backings, but I don't think maple is quite as strong, so I make them 1/16" thicker. However, with ERC, 1/8" maple should be plenty. I like maple... I've been using it more and more lately. Make sure your backing strips are quarter sawn, so the grain runs fuill length, with no run off. Good luck... keep us posted.