Author Topic: First HBO questions - Heat treat and dimensions.  (Read 1392 times)

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Offline BL

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First HBO questions - Heat treat and dimensions.
« on: May 08, 2014, 12:39:54 am »
I've starting in on a hickory-backed osage and am debating whether or not to heat treat the belly before glue-up.  Also, I'd appreciate people's thoughts on overall dimensions and backing thickness.  I have access to a thickness planer in the shop class at work but have read anything from less than 1/8" to 3/16" suggested for various woods.  This is my first time working with osage, and I'm really looking forward to it.  The guy at the mill I got the osage board from said he used to sell osage staves but ran out of business in the area years ago.  He pulled out a nice flat stave with the bark still on, about an inch thick and maybe 6" wide  that's been lying around for however many years, and gave it to me for 5 bucks.  Hopefully working with the lumber will get me some confidence to dig into the nicer piece.

Here's the current plan.
- Deflex-recurve profile, steam/heat bending the belly and backing lams into rough shape then adding overall limb reflex at glue up.  Aiming for 2-4" reflex overall after gluing and see what I can keep this time around.
- 60" overall length, about 8" deflexed stiff center with a 3/16" cherry powerlam.
- Width at 1.5" for first 6" of limbs then straight taper to 3/8".  (Boards are still currently at 2" wide full-length so I've got options here.)
- Target is 50-55# at 27", although I'll take opinions on this as well .  The person I'm building it for is currently shooting a 65#@26.5" compound and this is my best guess for where to place it.
- Rough osage thickness taper is currently 7/8" out to 1/2" at the ends.

Is it worth it to heat-treat the osage in this situation anyway?  If I treated it at the current dimensions would it be likely to penetrate deep enough to have any effect left after tillering down?  My thought was that the worst it can do is nothing, but I wouldn't mind saving the effort if it's a wash.

Thanks in advance!

Offline PEARL DRUMS

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Re: First HBO questions - Heat treat and dimensions.
« Reply #1 on: May 08, 2014, 11:54:33 am »
I wouldn't heat temper your core with a glued on back to be applied, it'll hold your reflex for you. The backing can start in 1/8" thickness and will be sanded and worked down nicely by completion. If the soon to be new owner pulls 26.5" on a wheely gun, he/she will pull no more than 25.5" on a bow. Nice score on that old stave he gave you for $5.
Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Offline BL

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Re: First HBO questions - Heat treat and dimensions.
« Reply #2 on: May 08, 2014, 05:58:19 pm »
Thanks PD.  I'll save the heat gun for all the elm and yew stacked in the garage.   ;D

Offline bushboy

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Re: First HBO questions - Heat treat and dimensions.
« Reply #3 on: May 08, 2014, 07:17:29 pm »
I like to preshape the core using the localized steaming method for the recurves and later go on to heat treat belly so it holds the shape that I want. I have done to many crooked glueups and find this works better for me to depend on a preshaped core rather than clamp pressure.I also believe a proper heat treating will penatrate the belly and give up less set
Some like motorboats,I like kayaks,some like guns,I like bows,but not the wheelie type.

Offline PatM

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Re: First HBO questions - Heat treat and dimensions.
« Reply #4 on: May 08, 2014, 07:36:18 pm »
 This bow doesn't have a core lam.