Heat treating selfbow timber
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littlejohn
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Heat treating selfbow timber
I'm making a selfbow for my young bloke out of silver ash and I was thinking of trying to put a bit of reflex into it. I've read that a number of species including ash benefit from heat treatment. I am a rank amatuer, I don't have a heatbox...Could I clamp the stave over a form or a jig to get my bend and use a heatgun to assist in this process???
Re: Heat treating selfbow timber
You can mate I found good results with hanging a weight on the limb and heating the area to be bent with a heat gun until it had bent a little more than you want and then let it cool there.It will lose a bit so allow a bit more.I would experiment with a bit of scrap the same size to see how it goes.
Cheers KIM
Cheers KIM
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littlejohn
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Re: Heat treating selfbow timber
Thanks Kim. I'll try it on an overly light selfbow I built in the past and see what results I get. Then maybe try again on the ash bow if successful. Pete
Re: Heat treating selfbow timber
Hi Pete,
I have had good results using steam. My steamer was made up from recycled materials [no cost].
Another method is to make a horizontal saw cut from the tips of the bow and take them a bit past where you want the recurve to start.
You can use a parallel or midly tapered strip of wood to insert into the saw cut. The parallel strip should be the same thickness as the width of the saw cut. If using a tapered strip the thin end of the taper should be matched to the saw cut.
Apply glue to all surfaces that come into contact, insert the strip and clamp the limb to the form.
Daryl.
I have had good results using steam. My steamer was made up from recycled materials [no cost].
Another method is to make a horizontal saw cut from the tips of the bow and take them a bit past where you want the recurve to start.
You can use a parallel or midly tapered strip of wood to insert into the saw cut. The parallel strip should be the same thickness as the width of the saw cut. If using a tapered strip the thin end of the taper should be matched to the saw cut.
Apply glue to all surfaces that come into contact, insert the strip and clamp the limb to the form.
Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken. [Ascham]
“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]
I am old enough to make my own decisions....Just not young enough to remember what I decided!....
For a good bow twice paid for, is better than an ill bow once broken. [Ascham]
“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]
I am old enough to make my own decisions....Just not young enough to remember what I decided!....
Re: Heat treating selfbow timber
Dry heat or steam is fine for recurving. Kims idea would be quite gradual and seems it could prevent any splintering issues. I have not used dry heat but steam. I'm first to admit I only tinkered around the edges with recurving selfbows as I prefer working with the curve balls nature throws instead of adding my own complications. I'm not trying to discourage you, quite the opposite get in there and have a go.
I used a baking tray of boiling water on my camp stove. I placed one limb tip over the boiling water and covered with foil, the other end of the bow was supported. I topped up the baking tray from time to time with more boiling water. I steamed the limb tip for about an hour then bent it around a form and clamped it in place and left it overnight. Then gave it a couple of weeks to dry out as I found out the hard way that if you don't do this the recurve will pull out.
I have found that if you try and bend to much of a recurve angle the belly side of the recurve will want to splinter some. You can reduce this by using a strip of strapping steel screwed to the form, you clamp it a fair way down the belly side of your limb as you bend it round the form. Theory is it will eliminate the splintering. Steamed or dry heated long enough you should not get much splintering. Bowyers Bible , chapter 6 gives a detailed description.
I also like static recurves and found it's a good idea to glue a lamination onto the belly side as it stopped any recurve pulling out with use. Alternatively you must leave the area around the base of the recurve thicker to resist bending. Best result I got was a Brigalow recurve and it did not need a belly lamination as I left the base of the recurve quite deep. I was lucky and the bow tracked straight so I also narrowed the limb tips and recurves to reduce mass, it was a static recurve.
Spotted gum worked well but did need the lamination on the belly side to keep it's steam bent recurve. In my limited experience I found a 20 to 30 degree recurve was ample on selfbows. Perhaps if I had of gained more experience recurving I may have got results with sharper angles. Again get in there and use steeper angles, plenty have in the past with great success.
I also think your choice of timber could lead to heart break. Silver Ash is very weak under compression and the only bow design it could work reliably in is a wide, flat, man tall design. I am aware of lots of folks trying Silver Ash for non recurved selfbows and without exception they have failed. One fella I know was a slow learner and just cut out a strip out of the limb that was full of frets and crysals and laminated another piece on and kept shooting it until it failed and he'd laminate another bit on, the bow exploded eventually. I think you'd be better served using the Silver Ash for arrow shafts.
regards Jacko
I used a baking tray of boiling water on my camp stove. I placed one limb tip over the boiling water and covered with foil, the other end of the bow was supported. I topped up the baking tray from time to time with more boiling water. I steamed the limb tip for about an hour then bent it around a form and clamped it in place and left it overnight. Then gave it a couple of weeks to dry out as I found out the hard way that if you don't do this the recurve will pull out.
I have found that if you try and bend to much of a recurve angle the belly side of the recurve will want to splinter some. You can reduce this by using a strip of strapping steel screwed to the form, you clamp it a fair way down the belly side of your limb as you bend it round the form. Theory is it will eliminate the splintering. Steamed or dry heated long enough you should not get much splintering. Bowyers Bible , chapter 6 gives a detailed description.
I also like static recurves and found it's a good idea to glue a lamination onto the belly side as it stopped any recurve pulling out with use. Alternatively you must leave the area around the base of the recurve thicker to resist bending. Best result I got was a Brigalow recurve and it did not need a belly lamination as I left the base of the recurve quite deep. I was lucky and the bow tracked straight so I also narrowed the limb tips and recurves to reduce mass, it was a static recurve.
Spotted gum worked well but did need the lamination on the belly side to keep it's steam bent recurve. In my limited experience I found a 20 to 30 degree recurve was ample on selfbows. Perhaps if I had of gained more experience recurving I may have got results with sharper angles. Again get in there and use steeper angles, plenty have in the past with great success.
I also think your choice of timber could lead to heart break. Silver Ash is very weak under compression and the only bow design it could work reliably in is a wide, flat, man tall design. I am aware of lots of folks trying Silver Ash for non recurved selfbows and without exception they have failed. One fella I know was a slow learner and just cut out a strip out of the limb that was full of frets and crysals and laminated another piece on and kept shooting it until it failed and he'd laminate another bit on, the bow exploded eventually. I think you'd be better served using the Silver Ash for arrow shafts.
regards Jacko
"To my deep morticication my father once said to me, 'You care for nothing but shooting, dogs and rat catching, and you will be a disgrace to yourself and all your family.' "
- Charles Darwin
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littlejohn
- Posts: 120
- Joined: Sun Apr 04, 2010 5:53 pm
- Location: sydney
Re: Heat treating selfbow timber
Thanks again guys.
Greybeard. I can see the logic in your method and how it would work but I feel a little underqualified to try just yet that method. I think I may have one of your longbows by the way?????It's marked greybeard 54@28 black glass over spotted gum???? Good shooter anyway.
Perry, yes I have also read that ash is more suitable for a wider(paddle shaped) configuration. The bow I orgininally intended for myseld, but went too hard and it is too light but shoots well none the less. So I decided to go out on a limb. shorten..try for some curve and give to my young bloke. I think you may be right. But I'm getting used to grief.. I guess the beauty of the selfbow is simply that you can get in there and experiment and give it a go. I see so many nice ones out there.So many times in the past I have sworn to give it all away and just buy the bows I want but I just cant let it go.....So I keep trying.
I saw a an English bowyer just drop a stave of yew into a bucket of boiling water(dont know how long he left it in for), and then bend and clamp the stave like a charm over a curved form.
Anyway....thanks fellas....Pete
Greybeard. I can see the logic in your method and how it would work but I feel a little underqualified to try just yet that method. I think I may have one of your longbows by the way?????It's marked greybeard 54@28 black glass over spotted gum???? Good shooter anyway.
Perry, yes I have also read that ash is more suitable for a wider(paddle shaped) configuration. The bow I orgininally intended for myseld, but went too hard and it is too light but shoots well none the less. So I decided to go out on a limb. shorten..try for some curve and give to my young bloke. I think you may be right. But I'm getting used to grief.. I guess the beauty of the selfbow is simply that you can get in there and experiment and give it a go. I see so many nice ones out there.So many times in the past I have sworn to give it all away and just buy the bows I want but I just cant let it go.....So I keep trying.
I saw a an English bowyer just drop a stave of yew into a bucket of boiling water(dont know how long he left it in for), and then bend and clamp the stave like a charm over a curved form.
Anyway....thanks fellas....Pete