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Author Topic: Heat getting around to back  (Read 1439 times)

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Offline bjrogg

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Heat getting around to back
« on: March 21, 2018, 01:19:15 pm »
I've had this problem before but seems like it's been more frequent with Osage. Is this enough heat to be worried about? It seems it just lightly changed color. What do you all do to prevent this?
Bjrogg
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Offline PEARL DRUMS

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Re: Heat getting around to back
« Reply #1 on: March 21, 2018, 01:30:37 pm »
BJ you can wipe a very light coat of veggy oil on the back to prevent that. That isn't too bad, but it is more dry and "brittle" than the rest of the back. Give it a day or so to catch up before you bend it.
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Offline bjrogg

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Re: Heat getting around to back
« Reply #2 on: March 21, 2018, 01:50:17 pm »
Thanks Pearl I'll give the veggie oil a try next time. Maybe it would help keep water stains off when steaming to? Man sure do like how this yellow wood bends. This is a stave that Frank probably hauled to every meet around for 25 years. Nobody took it and several others. He didn't feel like loading and unloading again and I feed him pretty good so before he left Marshall he made me a offer I couldn't refuse. It didn't look like much when I started but I think I see a bow in it now. Sure can tell this ones been curing for awhile.
Bjrogg
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Offline PEARL DRUMS

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Re: Heat getting around to back
« Reply #3 on: March 21, 2018, 01:52:48 pm »
Shellac will keep the water stains at bay when steaming. Welcome to the wide world of osage green horn :)

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Offline Badger

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Re: Heat getting around to back
« Reply #4 on: March 21, 2018, 01:57:03 pm »
  I started using a form without a back on it. I haven't had any problem like that, If I need my cawl with a back to straighten it sideways then I use oil on the back and heat from a bit further away for a longer time.
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Offline bjrogg

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Re: Heat getting around to back
« Reply #5 on: March 21, 2018, 02:04:47 pm »
Quote from: Badger on March 21, 2018, 01:57:03 pm
  I started using a form without a back on it. I haven't had any problem like that, If I need my cawl with a back to straighten it sideways then I use oil on the back and heat from a bit further away for a longer time.

How's that work Badger? Do you mean like three or four points of contact on a limb? This stuff needed to be wrestled onto my form cause it was anything but straight. Had the huge roller coaster thing going. Do you have pictures of your backless caul?
Bjrogg
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Offline DC

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Re: Heat getting around to back
« Reply #6 on: March 21, 2018, 02:10:17 pm »
Instead of a back I screw pieces of 3/4" plywood on anywhere I need something to clamp to or wedge against. If I want to heat near one of the pieces of ply I move them around so I'm not heating against them.
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Offline PEARL DRUMS

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Re: Heat getting around to back
« Reply #7 on: March 21, 2018, 02:11:44 pm »
I don't use a backed caul either. You can pull the limbs laterally with wood blocks and Irwin bar clamps, like Don mentioned. If they are bad enough you sometimes have to go back for a second correction.
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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 Springbuck

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Re: Heat getting around to back
« Reply #8 on: March 21, 2018, 03:52:19 pm »
  Yeah, a little of this is fine, but don't let it cook too much.

I went from clamping to flat or reflexed boards with shims (to give me the ability to straighten as I heat treat) to taking the time to make up an actual caul for each bow type and each kind of curve I'm working on.  I make them  "Perry reflexed", using 2-3 cheap pine 1x2 slats or cut-offs and bend them with blocks and clamps, then drive in a bunch of grabber screws in so they hold the position like a laminated bow does.   If they are narrow, it helps prevent the heat reflecting back as much, and if they are long enough I still get good enough control to crank out lateral bends.
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Offline bjrogg

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Re: Heat getting around to back
« Reply #9 on: March 21, 2018, 04:07:55 pm »
Yea I think one of the reasons I'm having more trouble with the Osage is because im making narrower bows.
Bjrogg
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Offline BowEd

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Re: Heat getting around to back
« Reply #10 on: March 21, 2018, 06:02:55 pm »
Yes I've used 3/4" wide forms so the heat flys by the 1 and 1/4" to 1 and 1/2"  wide bows and can't bounce back up to the back BJ after getting string alignment of course.Use them to dry heat temper recurves that had been steam bent too.
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