Primitive Archer
Main Discussion Area => Bows => Topic started by: nsherve on October 28, 2016, 10:13:20 am
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do ya'll use a hot air gun for heat treating? if so, do you use it up high, or in a lower heat? mine goes from 120 up to 400+....
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High about 4" away from the surface you are tempering.
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2x what Pearlie said
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A heat gun ranging from 550 to 1100 is what I use.It's a wagner brand.It has stood the test of time.Use it on high while heat treating like said 4" away from wood.Takes 3 to 5 minutes before starting to turn brown on most woods except black locust which turns color sooner.I've heard it said the reason being something to do with the amounts of sugars in the wood maybe???
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Celsius or Fahrenheit?
Yeah, I wonder which temperatures are best. from Marc St Louis's stuff, it seems like if you're heating the belly, the back should be.. around 200C?? not sure
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Forget F and C. Turn it on high, simple as that.
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Fahrenheit.Glad you spelled farenheit for me.....lol.I never check the temp of the back because it's on the form usually but usually the temp on the belly should run from at least 350 to over 400 degrees sometimes before moving on down the line of the limb or bending recurves.Thinner wood will get hotter quicker too.They all say wood plasticizes at 350 degrees.I believe it so too.I used to use a laser thermometer to know this but after enough usage of the heat gun you usually can tell when to move the gun along a little bit.If I want something to hold long term from bending wood or treating it needs to get hot enough.I don't care to redo something later on after the finish is on and all.
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I never check the temp anywhere. I heat a 6" area, moving the heat gun back and forth until I get the desired color then move on to the next 6" but I keep going back over what has already been heated. I continue with this until I get to the end of the working limb. If I am adding reflex or straightening I'll go back over the whole limb, reheating well as I go...then on to the next limb. I also like to be sure the wood is completely cooled and give plenty of time for the wood to re-hydrate before stressing it.
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The back does get hot but nowhere near 200 degrees. You should be able to lay your hand on the back for a couple seconds at least after heat-treating
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Forget F and C. Turn it on high, simple as that.
Thinking 1100F might be a tad too much.. :p
or maybe not?
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The heat the gun achieves has little to do with how hot the wood gets. That's up to you to control the heat by distance from the wood and how much you keep it moving.
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Ditto what Pat M said.At 1100 degrees it's not too hot for the wood.Gaurantee it.I can see why you might be a little apprehensive though since I'm the only one who seems to actually know what the temp is.Heat treating can take practice.You adjust distance accordingly to let the heat slowly penetrate as deep as you can.On the high side of the wagner gun at 1100 degrees 4" away from the wood will take a good 3 to 4 minutes to get up to 350 degrees.
Bottom line is don't hold it too close to flash fry your wood.That does more harm than good.Once you get the hang of it it's not that hard and it will be an invaluable tool in your bow making.Like Pat B said too though if the heating is done on the working portion of your bow limb though you should let the wood rehydrate a while.I have a 10 day rule I put on a lot of things.On non bending parts like stiff tips less than a day.
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My heat gun is pretty ancient, its got 2 settings; nearly melts paint, and, just about melts paint, but it works great for tempering wood
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Go to the archives section Mark has a demo on heat treating there
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I rifle drilled a 1" piece of Ocean Spray to about 6". I put a thermometer into the hole and aimed the heat gun at the outside. Top heat and 4" away. When the wood started turning dark brown the temp in the middle was 200 F. It was still climbing slowly but my thermometer only goes to 220 so I stopped. That's 1/2" of very dense wood. I don't know whether lighter wood would insulate better or worse but it shows that you could go very dark brown before there was any danger of overheating the back. I think the danger is in the convection heat wrapping around the bow and cooking the back. I've made a radiant heater that does a whole limb nicely in about the time it takes to get the first spot of brown with a heat gun. There didn't seem to be the danger of heating the back but it only works with straightish limbs. Reflex and deflex make it uneven. I'm trying to find a way to make it flexible so I can match its shape to the limb.
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I see DC...Interesting.Do you have a picture or better description of your radiant heater?
To tell the truth I've always been a little leary of heat treating these limbs say with multiple pins or knots along the back showing through to the belly.I've done it but still am leary.The knot wood seems to be a little harder already and too much heat might raise a splinter on the back of limbs after flexing to full draw.Assuming there is'nt a whole lot of extra reflex induced while doing this.Maybe other people have done this regularly and can chime in about their experiences with this.
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i really like the responses to my question... when getting a twist out of the wood, (it doesn't look too bad) do you do one arm at a time, or both?
(with said hot air gun)
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I generally clamp the bow to the form at the handle, the back of the bow down, and work out one limb clamping as I go and using wedges where needed. Then on to the next limb. There are some occasions where I only work one limb but that's not usual.
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Generally yes.I try to get the top plane of the limb the same as the top plane of the handle.Others may have success or do it different that's just me.There are different ways people will take propeller out too.Forms/wedges and by hand with one end clamped down but generally if the twist is'nt that much I just leave it alone.Lots of times if it is'nt much twist just bracing and shooting it will take it mostly out anyway at full draw.Experimenting trying different ways will show you what works.
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i really like the responses to my question... when getting a twist out of the wood, (it doesn't look too bad) do you do one arm at a time, or both?
(with said hot air gun)
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