Primitive Archer
Main Discussion Area => Bows => Topic started by: snowplow on October 19, 2015, 09:02:33 am
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Hey guys, I am super new to all this. I am working on a little r/d vine maple bow for my son at the moment. I steam bent the limb tips (which was super cool) not long after I harvested it. Now I am tillering it and it's bone dry. So far so good except the string does not bisect the center of the handle because I didn't leave enough material on the ends of the limbs to compensate. It's close enough to work for him, but I was hoping to bend the handle a bit.
Can you guys tell me a little about that?
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I'm not familiar with vine maple but you should be able to steam it to bend. I would seal the back of the area to be steamed with shellac first to prevent checking after it comes out.
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Yes you can. I would advise you to steam or dry heat both limbs to be equal to make tillering easy.
Dean
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I was under the impression that you need moisture in the wood to steam or especially for dry heat. Do I need to get it wet or anything. I think I have heard of cooking oil being used too.
How does the heat actually bend the wood and make it set?
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If you steam dry wood you need to seal the back with shellac so it doesn't check as it dries. Cooking oil works with dry heat(but I'm not sure about with vine maple). Heating wood makes it pliable so you can shape it. Once cooled it should keep most of shape you put into it.
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The heat softens the lignins so the wood fibers can move around. I've often wondered if the moisture in steam has anything to do with the bending. Maybe it's just the heat and using steam is a convenient way of making sure you don't get to much. And it's handy to work with.
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Ok, thanks guys. I'll give it a try.
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Try it on a scrap first.
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I'm not familiar with vine maple but you should be able to steam it to bend. I would seal the back of the area to be steamed with shellac first to prevent checking after it comes out.
Sorry my english is not enough (SWE), what dose "prevent checking after it comes out" means with other words?
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I have successfully steam bent lots of dry wood without protecting the back with no issues. I do not even think about it. Just see the steam as another way to transfer the heat to the wood to get it bending. Sure it changes the moisture content a bit but not to the point where it has checked when it has dried again. Perhaps only in certain woods? Saying that I only really use white woods.
I know some folk say dry heat for dry wood and some swear that steam should only be used on green wood. Dunno about that one.
Dean
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I just steam bent the reflex kink out of a hickory bendy handle I'm working on, it works very well on dry wood. And is often my go to method for larger imperfections.
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Thanks guys! Is there any rule of thumb for how far to 'overbend' to account for spring back when unclamped?
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prevent checking after it comes out,, means ,,, after you steam it the shellac can help prevent the wood from checking(cracking),,, some woods at some altitudes or moisture content,,,can crack from being heated with steam,,
there is really no rule for overbend, I would say try a little and if it is not enough try again a little,, better in small increments ,,than taking a chance on breaking or cracking the wood,,
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Steam bending to align the handle on vine maple:
http://www.primitivearcher.com/smf/index.php/topic,53195.msg722043.html#msg722043
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I always error on the "too much" side. After it's cooled for and hour or so unclamp it a see what it does. If it looks like it may be too much give a little pull on it. It will unbend quite easily for a while. I go 20-30% too much. Seems to work for the wood I use. Your results may vary yadda yadda yadda.
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Just boil it or steam it and it'll take whatever shape you want. No need to take precautions to prevent any checking. Bc it won't happen, not with this wood.
I like to hit it with the heat gun after its completely cooled to 'set' the bend. Probably not necessary but I do it with all woods
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Awesome info! Great note about being able to 'unbend' it easy! Thank you!
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I do this all the time with maple and elm, esp. Practically every bow. I would rig a form and just crank it over, cool and dry, slightly past the amount of correction you need, and go over the area you want bent with dry heat. Simple and effective. I will warn you to pay attention to what this does to the ROTATIONAL alignment, though. Sometimes you line up the tips linearly and find that the recurves are now in slightly different planes.