Primitive Archer
Main Discussion Area => Bows => Topic started by: maitus on March 20, 2019, 04:42:09 am
-
Any experience, included bad and advises?
-
I did some heat corrections on my latest (and first) sinewed bow. I therefore was advised to continously check the temperature of the sinew layer by infrared thermometer and to take care that the sinew layer didn't heat up more to than 60 degrees and the belly to not more than 120 degrees (celsius). I protected the sinew with a silver paper. I had mixed feelings doing that but it worked fine.
I can imagine that you could do a heat treating of the belly that way. In this case I'd heat treat the belly rather hot but short, so that not too much heat goes alltrough the limb. A slighter heat treating should be doable like that. Still I see some risks...
Cheers
-
I wouldn't attempt it. Not worth the risk for me.
-
Thank You guys!
I have heat treated rawhide backed bows a lot. There is no risk but im not sure with sinew. The next bow i will tiller and heatreat before sinewing. Im stupid :D...
I think simk-s idea with folium tape could work, if to tape edges on belly level.
Lets wait for more posts :).....
-
If you heat hide glue does it soften and reharden as good as new or does it degrade? Could you dampen the sinew/ hide glue a bit.
-
If you heat hide glue does it soften and reharden as good as new
True, but Hide glue and sinew also are made of proteins - they both soon denaturate if getting too hot - not reversible. I'd be careful somwhere above 60 degree ceslsius
(fish glue should be better and resists temperatures up to 160 degree celsius - says a book of mine)
-
It wasn't with hide glue(it was epoxy) but I managed to twist a laminated bow with a heating pad. I wrapped it around the limb and (most important) I put a thermometer in there and adjusted the pad until it was 150°f (65°c) inside. That softened it enough to twist. That said if it's just a bit out I wouldn't risk it. I guess you could strip the sinew off the offending limb and start again
-
If you heat hide glue does it soften and reharden as good as new or does it degrade? Could you dampen the sinew/ hide glue a bit.
No, dry hide glue will not soften with heat, it will bubble :D . The question is: is it possible to keep heat away form the sinew and does the heat go thru the limb and reach to the sinew. There is no way that sinew coult resist heat.
-
I have used a very damp but not dripping rag on sinew with no ill effects. Just heat the belly slowly and hold the heat source further away to avoid burning the sinew.
-
The question is: is it possible to keep heat away form the sinew and does the heat go thru the limb and reach to the sinew.
Yes, you can: Just heat heat the belly not too long but intense and make sure the hot airflow doesen't directly affect the sinew. That way only the wood close to the belly will be heat treated. Check temp of sinew with a cheap infrared thermometer.
Any liability excluded.
[sleek: congrats to your 5000-post-anniversary!]
-
Thank You for advises. I think i will take a risk to try :). I have an experience with heat treating elm selfbow which took some 15 cm set during tillering . After heat treating was the set 3cm and it keeps this set until today. So it worth to try.
-
The question is: is it possible to keep heat away form the sinew and does the heat go thru the limb and reach to the sinew.
Yes, you can: Just heat heat the belly not too long but intense and make sure the hot airflow doesen't directly affect the sinew. That way only the wood close to the belly will be heat treated. Check temp of sinew with a cheap infrared thermometer.
Any liability excluded.
[sleek: congrats to your 5000-post-anniversary!]
Oh, wow. And i spent it giving some dubious advice. Lol.
-
Seems some folks advocate for a quick heat, and im the only one saying do it slow. I guess I will explain why i say do it slow so i dont look stupid.
With a slow heat, its harder to overheat and burn the belly. Also, the heat soaks in deeper. A good deep heat treat is always ideal. Now of course you want the back to stay cool and thays what the damp rag is for. Of course that only helps so much, so you dont want to heat as long as you would without sinew. Just keep feeling the back and when it starts to get to the point of it being uncomfortable to hold your hand there for a solid min, you are at the threshold. When Im done putting heat to a belly, I take a wet not damp, rag and wipe the belly. With the belly facing up ( heat rises ) to cool it off as fast as possible. I feel doing less than this just doesnt make the effort worthwhile, the belly just doesnt get heat treated enough.
-
If you've ever dipped sinew in glue that is too hot it will immediately shrivel. How it acts in a matrix with hide glue I don't know.
-
I was reading about tillering horn bows last night and it's all about heat and wood and horn on finished bows. They heat and bend all the time. Maybe use their methods.
-
True, but they are just tweaking the bends and twists, not actually heat treating a limb.
-
Sorry, my mind wandered, I forgot the treating part :D
-
I’ve done it once. Propane scorch quick. I put it in a form with back set. No I’ll effects but I think it’s risky.
-
It can work. Less air flow and more heat. Thanks :)!
-
Has anybody used ironing for heat treating? Would it work?
-
I don't think it's hot enough. It has to get up to around 400°f. Unless your iron has a "Yew" setting ;D ;D
-
I checked, there is no "Yew" settings :D.. but if i would play a bit with heating controller...what You think?
-
I tried it on a sinew backed Osage many years ago. The sinew lifted in several places
-
You were heating the belly side, right?
-
I was wrong big time. I just checked my shop iron with my laser thermometer and when its turned right up to "linen" its 500°f. Should be plenty hot enough. I'll check after lunch to see where 400°f is.
-
I was wrong big time. I just checked my shop iron with my laser thermometer and when its turned right up to "linen" its 500°f. Should be plenty hot enough. I'll check after lunch to see where 400°f is.
[/quote
" Honey, what are you doing?"
"Oh just ironing out the hinges on this bow."
" Darling, when you are done, mind ironing out the hinges in the laundry?"
-
Ha! (lol)
oops she saw the post and it reminded her it's my turn to iron. :'(
-
It works. At least it gets the wood hot enough to turn colour. I ironed a piece of Yew that was 5/15-3/8" thick. In about 5-10 min the back side was about 180°f and the belly was in the high 300's, almost 400. I tried the wool setting but found that I had to go all the way up. The belly would have to be very flat. The advantage a heat gun has is it doesn't need a flat surface. If the iron went a little hotter it would work better. But in a pinch I bet you could heat treat a bow with an iron.
-
The next bow i will tiller and heatreat before sinewing. Im stupid
Strange thing about that statement is,,someone will attempt to do it that way and you will advise them otherwise and they will say how smart you are..You can look at it as "Im stupid" or " i just increased my knowledge" and became smarter..