Author Topic: Recurve Bending Problem  (Read 436 times)

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Offline Bayou Ben

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Recurve Bending Problem
« on: May 16, 2018, 06:06:12 am »
This is a live oak billet that I steamed for half an hour.  It's around 3/8" thick at the tips around 1" wide.  I steamed it then went right to the form and bent slowly by hand and watched the splinters lift.  Am I doing something wrong or would you think that live oak doesn't respond well to heat/bending?

Offline High-Desert

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Re: Recurve Bending Problem
« Reply #1 on: May 16, 2018, 06:14:23 am »
I've never bent oak, but I've had recurves spilt like that when I've rushed things. Splits like that are fixable with some TB, and clamps. The glue line shows up, but it's not terrible. Leave it in the form while gluing. A few things to help prevent splitting would be to boil rather than steam, or at least steam longer than 30 minutes, at least an hour,  use a metal strap over the recurve, and even pour boiling water over the recurve while slowly bending. These things have helped me a lot.
Eric

Offline gutpile

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Re: Recurve Bending Problem
« Reply #2 on: May 16, 2018, 06:14:52 am »
first off I would boil it 15 min per 1/4 inch of wood..second get a metal band to lay on belly of bend , this will aid in preventing splinters... very important...gut
to take from nature the materials needed to take from nature the meat needed...they all die from natural causes osage, rivercane, stone points,...

Offline osage outlaw

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Re: Recurve Bending Problem
« Reply #3 on: May 16, 2018, 06:16:38 am »
Was the belly down to one ring in the bending area?
I started out with nothin' and I still got most of it left

Offline Bayou Ben

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Re: Recurve Bending Problem
« Reply #4 on: May 16, 2018, 06:22:59 am »
No it wasn't outlaw. 
I had a metal band ready to go, but couldn't think of a way to get it attached quick enough so I didn't use it.  I should have known better.
I'll find a way to attach the band to the form next time.   

Offline DC

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Re: Recurve Bending Problem
« Reply #5 on: May 16, 2018, 06:45:12 am »
Attach the band ahead of time and heat everything. bend the end of the strap over a couple of times to make a lip that catches the end of the wood. The slot in your jig has to be the right size so the folded lip can't slip by. The strap can't be allowed to slip. It's purpose is to take all the tension and put the whole piece of wood in compression. Then it won't tear apart. That's just a scrap of wood in the pictures.
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Offline PEARL DRUMS/PEARLY/PD/DRUMS

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Re: Recurve Bending Problem
« Reply #6 on: May 16, 2018, 06:45:26 am »
A few things I see. Its too thin in my opinion. Also, I don't believe it was hot enough yet. I never use straps and never have issues. A strap wouldn't prevent that from happening, that's a bit more than a sliver popping.
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Offline Bayou Ben

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Re: Recurve Bending Problem
« Reply #7 on: May 16, 2018, 07:25:18 am »
Thanks guys.  I'll heat it longer and may try pouring boiling water on it too while bending.  And I'm going to add a metal band.  I like DC's setup. 
I don't think this crack is fixable.  I'll make another billet, but use this one as a test piece. 

Offline bjrogg

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Re: Recurve Bending Problem
« Reply #8 on: May 16, 2018, 08:02:07 am »
I'm thinking like Pearl said it just wasn't hot enough. I've never steamed oak but done a lot of HHB. I always steam at least 1 hour and usually more. It likes to lift splinters to. I've done enough HHB now to be able to feel if it's going to bend or needs more heat. If it doesn't feel right it gets more steam. I do use a metal strip especially for HHB. I don't think I'd dump boiling water on tip while trying to bend. Sounds kinda dangerous and I doubt it would do much. Experimenting with a scrap piece is always a good idea.
Bjrogg
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Offline DC

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Re: Recurve Bending Problem
« Reply #9 on: May 16, 2018, 11:20:37 am »
I found that this jig that Marc uses works really well http://www.primitivearcher.com/smf/index.php/topic,62668.msg878994.html#msg878994
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Offline Bayou Ben

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Re: Recurve Bending Problem
« Reply #10 on: May 16, 2018, 11:43:13 am »
Yeah, I bought every PA magazine that Marc has written an article in...he has that pic in a couple of his builds if I'm not mistaken.  It just seems difficult to make sure you don't introduce any twist that way.  And you have to find a way to hold it in place.  But it obviously works well for him. 

Offline Bayou Ben

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Re: Recurve Bending Problem
« Reply #11 on: May 16, 2018, 12:56:41 pm »
DC, I just read your explanation on your yew/maple bow.  So you are using that jig too? 
I thought about doing it that way but I had the concerns above.  How do you address the twisting and what do you use to hold the billet after bending?

Offline DC

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Re: Recurve Bending Problem
« Reply #12 on: May 16, 2018, 01:45:45 pm »
I have a prop that holds the bow at just the right height, The height of the vice plus a hair for the slope on the floor :D and there is a convenient shelf bracket that I can tie it to. One disadvantage is that the vice is tied up while it cools so I try to arrange it so I bend the recurve just before I go in for the evening. Marc said that he cools it for 20 min. and then locks it in with the heat gun then lets it cool for another 20 min.
The jig has to be attached to the vice otherwise you end up at least one hand short when you try to bend it. I take the  front jaw off the vice and run it's screw through one hole and use the other hole to reattach the jaw. Pull the strap and bow assembly out of the steam, clamp the tip and strap in the vice and bend, prop it, tie it to something solid and go have a beer. ;) 
Vancouver Island
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