Primitive heat treat methods

[DC]

There was a video posted here a while ago with a guy using a similar(wet sand with a fire on top)method but that was for steaming in reflex, I believe. The problem with these methods is that you can't see what's going on. They all have the bow buried so the amount of heat treat would be a crap shoot.  If you can't see the colour change I'm sure you would end up with hot and cold spots. Just holding it over coals like a hot dog it much simpler and more likely to be successful. My gut says that it's probably the best way. Even better than a heat gun. I made a radiant heater that does a beautiful heat treat, no spots or scorching the back, just a nice even brown. But, unfortunately, only on nice straight limbs. It's only 2" wide so any sideways bend means that spot gets missed. Holding it over a bed of coals and waving it around a bit sorts that out. I wonder if one of those propane radiant heaters would work. Anyone got one in their shop?

[Santanasaur]

DC I’ve seen flexible heating elements online before that could match the profile of any limb. I’ve been looking into how to set this up for the last couple weeks. Any ideas? i’ve also been looking into getting an abandoned salamander oven from a restaurant but that would only work for straighter staves.

 And I think you’re right about good coals being better than a heat gun. Those put out a lot of hot air but i’d rather use  radiation like in those propane heaters you mention and with the ‘hot dog’ technique to be able to see what’s happening. Id still like to insulate the back so i can go harder on the belly, I guess this brings us back to badgers heat tape post

[DC]

DC I’ve seen flexible heating elements online before that could match the profile of any limb. I’ve been looking into how to set this up for the last couple weeks. Any ideas? i’ve also been looking into getting an abandoned salamander oven from a restaurant but that would only work for straighter staves.

 And I think you’re right about good coals being better than a heat gun. Those put out a lot of hot air but i’d rather use  radiation like in those propane heaters you mention and with the ‘hot dog’ technique to be able to see what’s happening. Id still like to insulate the back so i can go harder on the belly, I guess this brings us back to badgers heat tape post

No ideas or I would have done it but that's straying from the "Primitive Methods". I think next bow I'll try the fire pit. Put my money where my mouth is. I may stray a bit and use charcoal briquettes. I have this feeling that it will be way faster than a heat gun. With the gun you hold in one spot for about 5 min(approx). With the fire pit you're doing the whole limb at once so maybe 5 min for the whole limb. 10 min and the bows done? Anyone done this? Must be someone. Maybe a little optimistic but still. And then you have a bed of coals to cook a steak or a squirrel or hot dog

[Santanasaur]

I’ve done this for about 10 bows. Only one or two have better heat treats than with a heat gun, but I’m chalking that up to poor experience/ability. I’ve ruined several bows over campfires. Takes me about 10 minutes a limb, 15 when I go very slow. Have had way better results with a long trench of glowing red coals than with an orange glowing campfire. A lot like cooking a steak but a little longer. I  look for where the coals are radiating heat and not where they are on fire and putting out a lot of hot air. Those spots leave a lot of soot and scorch the back faster in my experience. My hope is always to come back around to primitive methods but while figuring things out i don’t mind modern training wheels.

[DC]

I'm thinkin' a 3' long half pipe filled with charcoal briquettes. The equivalent of a trough in the ground but raised up on legs in front of a lawn chair. Maybe a cup holder

[sleek]

I'm thinkin' a 3' long half pipe filled with charcoal briquettes. The equivalent of a trough in the ground but raised up on legs in front of a lawn chair. Maybe a cup holder

You sir... are a genius. I will take 2 please.

Perhaps a mirror underneath it so you can see what's going on on the belly....

[DC]

Perhaps a mirror underneath it so you can see what's going on on the belly....

Now that's lazy

[Santanasaur]

Great idea, sounds much more comfortable than kneeling on the ground around hot coals.If you want the coals to last for both limbs i might go with a 5” pipe. When i have done trenches too thin i’ve had to light another fire to do the other limb which takes a while and hasn’t saved me any charcoal really.

[sleek]

Hey now, I like how this thread has progressed... Maybe we should make a DVD demonstration on this technology?

5 inch trench sounds reasonable.  Why not just make 2 trenches with an adjustable gap in between for the handle,  and hit both limbs at once?

[Pat B]

Fire was a major part of life for primitive man. I can imagine a guy building his bow while sitting around the fire using that heat to make adjustments as the bow building was going on but I can't imaging taking the time to dig a trench, fill it with hot coals and risking his hard work to temper the bow. Looking at primitive bows in museums I've seen things in their construction that we try to stay away from like grain violations on the back. Very few of the bows I've seen had pristine backs and apparently many survived. 

[PatM]

You'll see plenty of references to Natives using the trench and bury method for streaming a stave.
 
   Many cultures use some form of burying food in order to cook it.   If they could master the timing for that it's not that unrealistic that they could figure out time and temperature for a bow too.

  I still favor the simpler over the fire method.

 Several years ago a guy on Paleoplanet made a HHB bow on a camping trip and did a beautiful job of both drying AND heat treating the bow over a fire in just a few days.  I'll try to find a link to the thread.

[sleek]

Fire was a major part of life for primitive man. I can imagine a guy building his bow while sitting around the fire using that heat to make adjustments as the bow building was going on but I can't imaging taking the time to dig a trench, fill it with hot coals and risking his hard work to temper the bow. Looking at primitive bows in museums I've seen things in their construction that we try to stay away from like grain violations on the back. Very few of the bows I've seen had pristine backs and apparently many survived.

Fire treating one of those bows would be certain failure then... Interesting about seeing so many with violations.

[PatM]

https://www.tapatalk.com/groups/paleoplanet69529/five-curve-hhb-mollegabet-quick-cure-experiment-bu-t36201.html

[Pat B]

I know fire pits were used to cook food but that was for the tribe and not just to build a bow. I agree with Pat about sitting around the fire using the heat directly as the bow was being made. In primitive society every movement had a result. Very little time or effort were used if it didn't have direct results that aided the group.I have no doubt that a very good bow could be built from a green stave in a relatively short amount of time and the link Pat posted proves it.
Like I said in another thread it is almost impossibly for us as modern man to know how the primitive mind worked.

[bassman]

They cut  straight grooves the length of the arrow ,and  some even spiraled the grooves, and heated them over a fire to harden them to keep them from warping. When I build arrows from scratch I do the same . On most woods that I have used for arrows it works.Fluted arrows like fluted rifle barrels to a lesser degree.