Author Topic: about that steam bending....  (Read 13250 times)

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Offline bradsmith2010

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Re: about that steam bending....
« Reply #30 on: May 31, 2016, 03:34:33 pm »
Mad Max, some seal the wood before steaming, but not all do,,
your second question would depend on how much you want to bend it,, a slight adjustment ok, but something aggressive  I am not sure about that,, someone will chime in that has more experience than me,, :)

Offline Pat B

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Re: about that steam bending....
« Reply #31 on: May 31, 2016, 04:00:34 pm »
Mad Max, some say that sealing the wood before steaming is not necessary but I do seal(at least the back) with shellac. Shellac can handle the heat and moisture.
 You can steam wide, thick wood but you have to steam it longer to get the heat way down inside the wood. I would reduce it to almost bow thickness to insure I get good heat penetration before bending.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Mad Max

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Re: about that steam bending....
« Reply #32 on: May 31, 2016, 04:01:58 pm »
Mad Max, some seal the wood before steaming, but not all do,,
your second question would depend on how much you want to bend it,, a slight adjustment ok, but something aggressive  I am not sure about that,, someone will chime in that has more experience than me,, :)


about 30" Radius
I would rather fail trying to do something above my means, Than to succeed at something beneath my means.

Offline half eye

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Re: about that steam bending....
« Reply #33 on: May 31, 2016, 04:21:00 pm »
Max,
    I have steam bent wood the size in your question. My wood was not sealed ,and anytime I have steamed wood with some finish on it the steam has taken the finish off , or partially so, and the steam still penetrated.
    On your 30" radius question, if you are meaning either a full circle or half circle....you would need a mechanical jig and a live steam table. If you are talking about a partial bend (like the limb shape of a sweeping recurve) then that is very doable.
    The major enemy of steam bending is the time (temp loss) between steam and bending and how long it takes to complete the bend. A steam table pre-steams, and continues to steam throughout the bend. Most bowyers steam the wood, remove it from the steam and then move it to the jig, caul etc. And that timing (even seconds) is what can make or break the results.
    Maybe that will help you some.
rich

Offline DC

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Re: about that steam bending....
« Reply #34 on: May 31, 2016, 05:30:51 pm »
I use this method, modified slightly of course.
https://www.youtube.com/watch?v=--iPQIwSEJM
 I use bread bags usually. Get it all set up and ready to bend, steam it, clamp it, steam it a bit longer and then cut as much of the bag off as possible and then I aim a fan at it to cool it off. Leave it overnight. I find that a steamed curve will hold-- most of the time. The other are just the wood gods keeping me on my toes. Dry heat after the fact does seem to set the curve.

Offline Mad Max

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Re: about that steam bending....
« Reply #35 on: May 31, 2016, 07:02:40 pm »
Yea  a piece about 18" long
I will come up with something to keep it steaming while I bend it.

I saw that youtube once before
Thanks guy's
I would rather fail trying to do something above my means, Than to succeed at something beneath my means.

Offline Pat B

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Re: about that steam bending....
« Reply #36 on: May 31, 2016, 07:14:30 pm »
Some woods like hickory bend better and hold their bend better when steam is used, in my experience.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline BowEd

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Re: about that steam bending....
« Reply #37 on: May 31, 2016, 07:30:37 pm »
Cool thread half eye.
Very cool catch DC about that steam bending bag too.
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline Arrowbuster

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Re: about that steam bending....
« Reply #38 on: May 31, 2016, 09:56:05 pm »
I got a question concerning steam. I steamed the bow that I am working on now to do some adjustment on straighteners and bend a little reflex in it.I didn't seal it. I ended up with some cracks in the wood that ran with the grain, they were not a result of any bending they were in the mid area and I didn't align anything there. Is it possible I just left it in box to long and dried it out to much?

mikekeswick

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Re: about that steam bending....
« Reply #39 on: June 01, 2016, 03:32:36 am »
Cracks/checks are always wood drying too fast. Outer fibers dry and inner fibers have no air contact and aren't drying (or at least as fast). So something has to give = checks.
Halfeye - I hope I didn't offend you. I was merely adding another example of steam bent wood keeping its shape. It's not my fault that people have come back with comments that have little sense in them. If somebody says one of my statements is incorrect i'll always do my best to corroborate what I have said.

I'd love to have met the people who made those wheel rims - they would have had to have known their stuff to have been able to make them and anybody who is skilfully in making things deserves my respect.

Offline half eye

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Re: about that steam bending....
« Reply #40 on: June 01, 2016, 07:24:50 am »
Arrowbuster,
      If you subject wood to steam for long periods you are drying it out to nothing. What I mean is if you cover a piece of wood and steam for a few minuets the wood will look "wet", but you leave that wood in the same set up for 30min to and hour and the wood will come out looking "dry" Thats because the wet heat will actually "cook" all the moisture out of the wood cells if you let it....any wood that you completely dry in an hour is going to check.....so I am guessing that you may have steamed your wood to long. Another example of liquid drying out wood, is a technique that some Japaneese wood workers use to dry logs.....they leave one end of the suspended log in a movinbg water body (creek etc) untill it is cured out.
   
Mike, no sir you did not, the situation was exactly as you described it to be. I was trying to show some steam bent wood that has survived time despite being ill-cared for. and hoping to get others to share some of their examples of the process.
rich

Offline Aaron H

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Re: about that steam bending....
« Reply #41 on: June 01, 2016, 09:10:16 am »
So I have always gone by the general rule of thumb that you steam for half an hour per half inch of thickness to bend.  I use that rule for both getting an even gentle reflex, and doing more aggressive recurves as well, mostly using Osage.  I always coat with shellac before steaming, but sometimes I will also end up with cracks on seasoned wood (1 year +).  Am I steaming too long, and the results being the cracks? Or is it that there is still too much moisture remaining in a 1 year seasoned stave that is causing this with the prolonged steaming?

Offline half eye

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Re: about that steam bending....
« Reply #42 on: June 01, 2016, 09:30:44 am »
You can very easily satisfy your curiosity if you have some scrap osage.....say 1/2 to 3/4 inches thick width doesn't matter as long as they are fairly the same. Steam one for a full 5 minuets, remove from the steam and immediately bend it over your leg or knee etc. Hold for a couple of minuets..... Now do the same with the other piece but leave it in the steam for 35 to 40 minuets......I think that you will find the second one to act like a too dry stick and think you will get some wood damage. 
    I have bent quite a lot of osage orange with the short time deal and have not had any real issues. I have not bent any of the 90 degree statics because I dont make those bows so cant say as to that but I have bent some fairly sharp tips with good results.
    Anyway you can give it a try on some scrap and then you can judge for yourself. You may not like it at all for the type of bows you build.
rich

Offline Aaron H

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Re: about that steam bending....
« Reply #43 on: June 01, 2016, 09:47:03 am »
Yea, I believe you are correct Rich, I need to go do some experimenting. Thank you

Offline BowEd

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Re: about that steam bending....
« Reply #44 on: June 01, 2016, 09:55:37 am »
I have many Amish around me here.Their wheels are pretty nice.Seems a boy coming of age say 18 years or so has to build his own buggy for himself.To go look for a wife most likely......lol.The dad helps though too from what I've seen done.I'll have to inquire from them a bit more once.They are very open about taking about that here anyway.
BowEd
You got to stand for something or you'll fall for anything.
Ed