Primitive Archer
Main Discussion Area => Bows => Topic started by: swamp monkey on November 18, 2013, 11:04:09 am
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If ya'll wanted to bend oak would you use dry heat, oil and heat, boiling or steaming? If you choose the last two for how long?
I have used dry heat on hickory and Osage with great results. Oil too, but now prefer the dry heat. I have steam bent hickory with good resultstoo. I tried to heat bend oak with dry heat and steam. None provided me with stellar results. In fact I did some test pieces on the steaming and I obviously did not have them warm enough because the wood didn't budge.
Your advise is welcome.
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Is this a board? Boards can be a real pain. When we bend stave bows we are generally bending with the grain either forward or backward. Trying to bend 1/4 sawn lumber can be a pain because your, in essence, performing a lateral bend against the natural growth of the wood.
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I recurved an oak a few months ago and used steam. Once its on the form I put the heat gun on it for a few minutes before bending. As I recall there was a little surface cracking on the belly which I sanded off later and it came out fine. I steamed it for a good 45 minutes.
The other day I was heavily reflexing the upper limbs on an oak that had taken a lot of set there. I used dry heat for only about 20-30 minutes since this was a finished bow and the limbs fairly thin at that spot. Both limbs cracked beyond repair. I assumed it was because I didn't use heat long enough but it might be because the belly had taken a set and I was bending it backward too far.
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pearl.
Yep, quarter sawn stave. However, I cut a V notch in it to replicate something the Eskimos did to get retrograde tips. So the part i wanted to bend was s small section with a v notch that reduced the bending portion down to 1/4" or more.
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I've bent oak pretty successfully with steam. I don't think it has the oils like woods who like dry heat or oil and heat. If I had To use heat I'd use crisco shortening rubbed on.
I'd use steam. Specially with that u described.
I'd also press pearly a little for his take
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Ahhh, Hupa like tips. Id try that bend on a scrap chunk. Cut the relief out and try it. Those are tips that get wrapped tight with sinew right?
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Definitely use steam or boil it. I boil 1/2" thick red oak limbs for an hour and then bend them over a form no-problem
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Pearl,
Same concept as the Hupa tips, but move four to six inches down the limb. The attached image shows the progression from left to right. The cable lashing holds the stiffening wedge in place.
This is a cable back bow.
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use steam swamp monkey, and do a practice run on a scrap pc, I haven't had any luck bending oak with dry heat at all
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That notch being cut changes the game totally. He will have a miniscule amount of wood to bend safely. Id try a practice run with heat and steam. I think the heat gun will be fine for this job.
I guess Im just a dry heat fanatic and use it for every thing but statics. Ive moved some bow tips laterally a long ways with dry heat.
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he didn't say if it was white or red oak, big difference between the two, all I know is what experience I've had and I've had zero luck with red oak and dry heat on tips but i'll defer to pearlie on this as he has more experience with dry heat
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Actually bub you stinkin'.....awwww nevermind.. ;)
He will only have a snippit of wood left after he cuts the wedge out. It will take minimal and gentle heat to bend it and not break anything. Im thinking steam is too harsh and uncontrollable....but, I have never did what he is doing. Im speculating.
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that's a good reason to do a test run, I think if its white oak dry heat will work great, it bends like rubber
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Test run would be essential, and a breeze.
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Ive only lightly reflexed redoak with dry heat but i did see the Woodwright guy bend a red oak board 180* with steam and it was 3/4" thick x 6" x 16"...so im sure its possable ;)... Brian
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I tried this kind of bend way back when I was trying to replicate a native bent cedar box. I put a "V" notch about 7/8 of the way through and boiled the wood. They all broke. I'm thinking that the bottom of the notch should be squared off some. That would give that sliver of wood room to bend. Just thinking out loud.
Don
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I'm very much a novice where bowyery is concerned, but I am a long-time woodworker and cabinet-maker. From what I know of wood bending (not all that much really, but . . . ), I am surprised that that people have found a difference between sources of heat from species to species. My understanding of the mechanics of heat-bending is that the heat (from whatever source) causes the lignin to soften thus allowing the cellulose fibers to be rearranged. When the piece is cooled, the lignin re-hardens fixing the fibers as they have been re-configured. Thus, it seems to me, the source of heat should only make a difference only insofar as one source penetrates the wood more or less effectively than another. Would appreciate any insights.
Best,
Tom
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I'm guessing you are right, Tom. I think that the differences in source heating that you read about here are mostly individual experience and preference vs. what actually works or not with the different woods.
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I cut a nice piece of quarter sawn red oak into sections so I could test bend them. The first I applied dry heat. I didn't do more than give the wood a slight tan but it was hot to the touch. It did not even budge.
I placed three other test pieces over a pot of water on the stove. 45 minutes over the steam. Two of the three resulted in broken fibers on the side without the notch. The other one did not bend nearly so much.
I am thinking I need to tweak something.
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Did you try to bend the dry heat test until it broke? Or did you just tunk it and it didn't budge? Id like to go home and try it myself to, but I have zero oak that isn't stained and going around the bottom our our walls!
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If I was bending something like that I would round file the very bottom of the v slightly.
Since the steam tore out the belly then I'd try more dry heat.
Use crisco and get it all over. Heat about 4" from each side of the wood. Yes it'll be hot to the touch but u want the inside to get nice and warm. Think of it as a burger on the grill. U can get the outside almost burnt and the inside raw if not heated properly. If u have more oak then try the steam and the heat. Both with crisco.
Pot on the stove crisco the place h want to bend. Cover tight in tinfoil to trap the steam. I put the bow in when the water starts boiling.
But I think dons idea is key. U can't stess that little section so much. Also use a pressure strip to help hold fibers done
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When we made canes with crooked tops in Scouts, we boiled the ends of each for what seemed like eternity, (...hey I was an 11 year old!), but we were able to bend those over like butter. It was probably a couple of hours. I remember that we had to feed the fire and add more water to the pots over and over again. They were made of cheap oak trim boards, so maybe...
OneBow
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i recently did a oak recurve with steam, it was made from a board. i roughed it out and then steamed for 40 mins. bent nicely without lifting a splinter on the belly. the wood was 13mm thick
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I just did a test run with riftsawn red oak and a notch filed in it like the pic, steamed it for 30 min and didn't get much bend before it brock across the belly, and yeah pearl's I bent it till it broke clean off, I think that notch should be fairly deep, I don't know could a been a crappy pc of oak too
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I put some serious hooks in a quarter sawn red oak board by boiling and bending with a metal strap. The strap made all the difference. Wood was .5" thick and .75" wide. I took the form from a glass recurve. Both of the bows I did it on chrysalled horribly, but my recurve form and technique worked great! I think I boiled for 1/2 an hour. I feel like you could get that bend without the notch, just use a strap on the belly.
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I did use the strap, I think the notch is the problem, it concentrates the bend in one specific spot
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Here's a link to how this one guy does bent cedar boxes. I'm not sure if this will work for you.
http://www.bentcedarbox.com/
Don
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Pearl, on the dry heat I couldn't get it to bend. So i couldn't bend it until it broke unless I Hulked out >:D
blaflair2, I like the idea of rounding out the V bottom. I will have to check my pics of authentic Eskimo bows but there may have been a slight gap in that location. Your method would explain that nicely.
Bubby, Did you use tin foil? I confess for my tests I did not. How does this tin foil contraption work?
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I just used the foil to cover it, ya know a couple of issues back Mark St Louis had an article combining steam and a heat gun perhaps that would work for you
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Ive done that bub, it worked when nothing else did on a lateral move with yew. Take a square of cotton t-shirt and get it wet through. Wrap it around your bend area and then cover that with aluminum foil and seal it the best you can. Then heat her up! Its a gentle steam I guess and it works.
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I swear by the localized steam method!in my view because the steam can't ecape as readily it raises the pressure slightly ,therefore the steam carries more btu's(calories of energy) than normal steam!
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that might be why steaming in a microwave works so well
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that might be why steaming in a microwave works so well
in a microwave? :o
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Yea in a microwave
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Yea in a microwave
what? how do you fit a bow in the microwave?
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Yea in a microwave
what? how do you fit a bow in the microwave?
Through a microwave... Cut holes in door and back side.. Don't use your mom's
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And don't stand with your groin lined up with the holes :o :o
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And don't stand with your groin lined up with the holes :o :o
+1 Bad idea :( :o
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I have a curtain I put over the holes with a damp cloth... It's magnetic energy.. pacemakers not a good idea... DonC thanks for the laugh.. Where else can you bend wood and heat up your pizza??
Thanks Leroy