Primitive Archer
Main Discussion Area => Bows => Topic started by: apg on August 01, 2019, 09:44:43 am
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Hi everyone,
So I’ve made about a dozen Osage bows with varying levels of success, though the one sticking point I’ve struggled with is heat treating to flip the tips.
I’ve always used dry heat - oiled limbs and a heat gun - and I’ve always gotten cracks. Some are manageable others not. I’m planning on steaming my next bow.
How does this look for a set of instructions I pieced together from different sources:
. Work limbs to very close to final tiller
. Using big pot of water and a sort of aluminum foil tube, steam limb for 30 minutes
. Insert limb into jig, use medium weight to let bow drop along line of jig to prevent over pressuring from me
. Clamp limb to jig and leave overnight to cool
. Repeat with other limb
. At this point if there’s any remaining twist or issues with string alignment I’ll fix it with a bit of dry heat
. Work bow to final tiller
Does that seem about right? Am I way off anywhere? Do you all have any tips? Will post photos as I go on this board if you like..!
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Here’s the best video I’ve found so far from my favorite bowyer:
https://m.youtube.com/watch?feature=youtu.be&v=JllYjPwi7Wc
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I have had mixed results with dry heat. My cracked tips usually have occurred due to a sharp corner of the belly to the side of the limb. I find that a thin strip of metal like an aluminum yard stick helps keep splinters from lifting.
I am definitely going to try the boiling water method. Thanks for posting!
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Keep the apex of the bend on one ring, that helps a lot. Feather out grain will pop very often, but not always.
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I ALWAYS use a strip of sheet metal on belly on bend to aid in preventing splinters if I haven't worked that part to a single ring.. plus I boil mine while thicker too. 15 min per 1/4 .. reason is if worked to near final dimension more than likely it will eventually pull out... plus I make all my recurves static... gut
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Not sure what you both mean by the metal - do you mean sort of wrapping metal around over the belly while you bend?
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yes.. I use sheet metal strip .. its about 1-1/2 wide... I put it in jig under clamp part of jig.. belly of bow.. it will aid in pulling splinters while you make the bend fast... works great... gut
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apg,
Here's a tip of mine from an earlier thread on the subject:
Go to the building materials section and look for anchor straps, which are used to tie roof rafters to stud walls. They are paper-thin, galvanized steel, which bend easily and won't rust in the wet conditions or boiling/steaming. They are about 1 1/4" wide and have a series of nail holes in them. The ones I had were about 20" long, I think. I cut mine down to about a foot long. Make sure whatever you get is at least a foot long, so you can clamp the strap to the limb, well outside the area to be bent.
I just recently started using straps to bend my recurves, and I wish I'd done it years ago! Takes all the heartache out of bending tight recurves. With the straps, you get no splintering or cracking in the belly. My personal touch to the strap approach, was to put one end of the strap in my vise, a 1/4" deep, and bend it over into a tight 90deg. bend. This will give you a 1/4" long catch on the tip end of the strap (think of the tab on a tape measure), that will keep the strap in tension, when you put the limb in your jig and bend it around.
–John
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Working the belly to one ring is very important.
No need to go close to final tiller in fact I would advise against it. The point of recurves is to keep string angle low which equals more effective leverage to bend a thicker limb thus storing more energy.
I bend my tips at 5/8th thick.
Boil them under water for 45 mins.
If you want a tight bend either do it when the stave is still green or soak the tips in water for 3 days to a week.
If you follow these steps then you don't need a strap even for tight 90 degree or even just past bends.
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So it’s not really steaming limbs - it’s really just putting them into a big ol pot of water or a kettle and boiling them??
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You can go either way. When steaming on a pot you have to prevent the heat from the source from scorching the bow part outside the pot.
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If you only want to recurve you don’t need to make your set up so involved.
The 90 degree static I finished a couple months back I did with a localized steam bend.
I what I do.
Wrap the tip to be bent in a wet paper towel (in between soaked and damp) wrap this in aluminum foil making sure the ends are pressed down tight in to the limb( the middle can be looser for the steam to circulate)
Clamp the tip of your now damp bow in what ever jig you are using, heat with a heat gun until it bends, clamp it and come back and check on it in the morning.
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I have mixed results with dry heat, better results with boiling and less cracking if any.
Clay Hayes said he stopped getting cracking with dry heat when he heated the imb tips from the side and stopped heating the back or belly. I haven't tried this and will probably continue to use boiling water.
I stopped using a back strap to keep splinters down, if you go to one ring and do things right you won't need a strap.
Virgil Louis, the master Alabama maker, has probably bent thousands of bow tips, he said he made 50 to 75 bows a month, most of them with flipped tips. He said he soaked his limb tips in water for 24 hrs before he boiled them and made the bends. He said he never had a cracked tip. Osage dust allergies turned him to other woods, anything from ERC to hophornbeam, he bends them all without problems.
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Okay sounds good - but what’s the dry time on these limbs before you string and draw???
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Steaming actually dries limbs out as the moisture expands out of the limbs, water expands by a factor of 4000 changing to steam, the water in the limbs changes to steam. Best to let the limbs rehydrate for a couple of days before stringing.
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You can seal the area to be steamed or boiled with shellac to help prevent moisture from entering the wood. I doubt that much moisture does enter the wood. I't the heat and not the moisture that makes the wood malleable.
Depending on where you store the bow after steaming/boiling as to how long it takes to dry but I'd give it at least 24 hours and maybe 48.
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You can seal the area to be steamed or boiled with shellac to help prevent moisture from entering the wood. I doubt that much moisture does enter the wood. I't the heat and not the moisture that makes the wood malleable.
Depending on where you store the bow after steaming/boiling as to how long it takes to dry but I'd give it at least 24 hours and maybe 48.
This brings up something I just discovered. For all the time I've been bending Ocean Spray it always turns grey when I steam it. I seal my staves with shellac. This last time one limb turned grey so when I did the other I cleaned the shellac off with lacquer thinner first. This one didn't turn grey. So something about OS and shellac and steam=grey. It doesn't come off afterward. I don't know if some other woods do this but it might be worth running a test on a new to you mixture.
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I use a wallpaper steamer and an aluminum heat tube. I've tried the pot of boiling water and the wallpaper steamer is much easier. Plus there's no risk of scorching the bow tips from the heat source.
(https://i.imgur.com/NqjJH5v.jpg)
(https://i.imgur.com/K4gjBiC.jpg)
(https://i.imgur.com/tjIHBlJ.jpg)
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Clint's steamer is the bomb. He had it at the Classic and built a recurve while there. The steamer worked great! :OK