Primitive Archer
Main Discussion Area => Bows => Topic started by: mmattockx on May 02, 2020, 12:19:00 pm
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For the guys that heat treat do you leave the bow on the caul until it is cool and then remove it to rehydrate while relaxed or do you leave it on the caul for several days while it rehydrates? The wood in question is maple and red oak if that matters at all.
Thanks,
Mark
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Some leave it a couple days. I've always waited at least a few hours if not overnight.
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I wait tell it cools at least 45min & then let it set 9 days or more to rehydrate !
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I leave it overnight.
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As soon as it is cold you can bend again.
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...yeah, but be sure it has cooled all the way through. I wait at least over night and if I'm gonna draw it more than half way I leave it for a few days.
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A few days at least.
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are you heat treating to reshape or just to harden the belly?
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are you heat treating to reshape or just to harden the belly?
Mostly to harden the belly wood, but I like that I can pull some of the set out after I finish tillering. I am not trying to significantly alter the side profile at all, just get it back closer to straight.
Mark
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I like that I can pull some of the set out after I finish tillering.
is it better to heat treat before the bow takes set or the belly acquires much cell compaction? maybe at 20"- 22"
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is it better to heat treat before the bow takes set or the belly acquires much cell compaction? maybe at 20"- 22"
Good question, one for the experts on heat treating here. It wasn't my plan to allow a bow to take a lot of set and then count on heat treating to remove some of it. I just look at it as a bonus side effect of the heat treating after the bow is tillered. Avoiding set in the first place will always be the better way to go overall.
Mark
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Avoiding set in the first place will always be the better way to go
Of course. Its just that there is also the so called "compaction" or "hidden set" that occurs before apparent set becomes noticeable. I recall some one heat treating as they go or maybe twice? Just cant recall the details or the outcome.
My thought is that with all the TLC we give to a piece of wood from beginning to end, any way to prevent damage is worthwhile.
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All depends on how deep was the heat treating. Until several months ago, I did not do any full heat treating of the whole belly. After I got the silicon heating pad, I have been heat treating many of my old bows, over twenty of them for now. When I did really deep heat treating to make the belly dark brown, I gave them more than a week to rehydrate. Still I suddenly broke two old oak bows on full draw, after many years of no such failure. They have been heat treated with the heating pad for more than an hour until the wood smoked a little. That was clearly too much. Now I stop at light brown and never more than a hour. I also simply measure the weight of the bow in grains and wait until it stops getting heavier or even lighter. Be safe.
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All depends on how deep was the heat treating. Until several months ago, I did not do any full heat treating of the whole belly. After I got the silicon heating pad, I have been heat treating many of my old bows, over twenty of them for now. When I did really deep heat treating to make the belly dark brown, I gave them more than a week to rehydrate. Still I suddenly broke two old oak bows on full draw, after many years of no such failure. They have been heat treated with the heating pad for more than an hour until the wood smoked a little. That was clearly too much. Now I stop at light brown and never more than a hour. I also simply measure the weight of the bow in grains and wait until it stops getting heavier or even lighter. Be safe.
Do you mind telling me where you got your silicone pad? I would rather buy one I know works. :D
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scp,
when using the silicone pad. have you measured the temp of the back during a treating session, or tried to draw the heat off the back or keep it moist during the treatment? I presume the broken bows broke in tension from a too dry back? (or the back is now effectively working against a different belly "design")
thanks
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All depends on how deep was the heat treating. Until several months ago, I did not do any full heat treating of the whole belly. After I got the silicon heating pad, I have been heat treating many of my old bows, over twenty of them for now. When I did really deep heat treating to make the belly dark brown, I gave them more than a week to rehydrate. Still I suddenly broke two old oak bows on full draw, after many years of no such failure. They have been heat treated with the heating pad for more than an hour until the wood smoked a little. That was clearly too much. Now I stop at light brown and never more than a hour. I also simply measure the weight of the bow in grains and wait until it stops getting heavier or even lighter. Be safe.
Do you mind telling me where you got your silicone pad? I would rather buy one I know works. :D
Thanks
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I recall some one heat treating as they go or maybe twice? Just cant recall the details or the outcome.
I have seen people mention here they heat treat before any tillering, during tillering, or after tillering and sometimes multiple times if they have scraped off all the treated wood during tillering. It doesn't seem there is any particular way that is settled as the best option. Your questions make me think I should try heat treating the next one much earlier, maybe after I have it to full brace before working the last 6" or so to full draw.
Mark
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It doesn't seem there is any particular way that is settled as the best option.
Seems to be some discussion lately of different methods. Multiple treatments with a hand held heat gun or fire pit would be very tedious, but if a guy had caul optimized for use with one of those silicone pads, a way to keep the back from getting too dry and maybe a timer for the rheostat etc. I can visualize a workflow that could keep the wood toasty as the tillering progresses.
Just brainstorming of course. Please let me know if it's out of line for this thread, Mark.
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Seems to be some discussion lately of different methods. Multiple treatments with a hand held heat gun or fire pit would be very tedious, but if a guy had caul optimized for use with one of those silicone pads, a way to keep the back from getting too dry and maybe a timer for the rheostat etc. I can visualize a workflow that could keep the wood toasty as the tillering progresses.
Just brainstorming of course. Please let me know if it's out of line for this thread, Mark.
Not out of line at all, I am trying to learn the better ways of creating bows. Asking questions and kicking ideas around are the best ways to figure these things out.
The silicone heating pads are intriguing to me, but I think I will be sticking with my heat gun for the near future.
Mark
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I leave it overnight.
+1
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Ive had very similar experience to SCP with the heating pad. I got mine on ebay for $25 but haven’t been able to find that price again, and I’ve been looking because I want a backup. Mines 3”x24” It’s one of the briskheat pipe heating ones, but as far as I can tell the silicone instrument benders are similar. On amazon the same product is over $200. I wouldn’t pay that much for it, it’s not well made. I had to use it outside for the first 10 hours or so because of plastic smoke. So I’m only recommending the generic product type and not necessarily that brand
It easily gets hot enough to make smoke and turn the wood back. I’ve had best results with a slow 45 min treat with the dial set around 300-350
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I leave it on the caul until it's cold but don't tiller for at least a day after
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scp,
when using the silicone pad. have you measured the temp of the back during a treating session, or tried to draw the heat off the back or keep it moist during the treatment? I presume the broken bows broke in tension from a too dry back? (or the back is now effectively working against a different belly "design")
thanks
Mine comes with an analog thermostat. But I still used a digital thermometer to make sure the belly does not go too much over 170C (338F), at first. I do it dry and put some weight like a clay bead bag on top of the heating pad over the belly. It can make the back of the bow too dry and brittle, if left on too long. Earlier I forgot to measure the weight of the bow carefully before and after. But deep heat treating for about 45 minutes does appear to prevent set, even when I leave the bow stringed many days.