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Bend in bow limbs (Read 3379 times)
vetryan15
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Bend in bow limbs
Jul 10th, 2020 at 7:45pm
 
Here is the 3rd attempt at a bow i have been working on. Its a maple at 65in long. I am not going for a specific poundage, just so i can get use to making em. The only tools i have used are the hatchet, and rasp. Just to see if i can make one with the least amount of tools, plus if i ever want to work on one while camping, or something along those lines.
      Now iam finally going into the tillering part, and taking it off a bit at a time. Now i dont get much time to work on it. Anywhere from a 1/2 hour to a full hour at a time, and maybe a couple times a week i get to go at it. Now this bad boy has a wicked bend in the limbs, i tried to show it off but i dont think the pics can show i off, you might have to zoom in.  But short of giving it a full steam bath and using clamps to get it to bend relatively straight,  what can  i do?  Just curious unless i should just keep working on it, and leave the bend in em. I also noticed thst since i am right hsnded, and do most of my work that way. One side of the limbs is thinner then the other, i figured i should justt flip it over more often and rasp it down like that. What do you think??
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walter
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Re: Bend in bow limbs
Reply #1 - Jul 10th, 2020 at 8:16pm
 
I think it is important to make both sides of a limb the same thickness otw it will twist. Also, both limbs need to be the same thickness from the grip to nocks. Like a mirror image
I think this is why I haven't broken a bow yet.
You will know if you have to steam bend it if you run a line from tip to tip and that line does not hit ctr of handle.

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vetryan15
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Re: Bend in bow limbs
Reply #2 - Jul 10th, 2020 at 8:17pm
 
Here are i hope better pics. Iam holding the stave straight.  But one side almost rotates.its gonna be a thin small poundage bow but something for me to practice with.
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vetryan15
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Re: Bend in bow limbs
Reply #3 - Jul 10th, 2020 at 8:19pm
 
walter wrote on Jul 10th, 2020 at 8:16pm:
I think it is important to make both sides of a limb the same thickness otw it will twist. Also, both limbs need to be the same thickness from the grip to nocks. Like a mirror image
I think this is why I haven't broken a bow yet.
You will know if you have to steam bend it if you run a line from tip to tip and that line does not hit ctr of handle.


So far all my work has been done with a hatchet, i am now starting to just use the rasp, and get into tillering. Its still a long way to go.
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joe_meadmaker
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Re: Bend in bow limbs
Reply #4 - Jul 11th, 2020 at 1:43pm
 
What you have going on there is usually referred to as "twist".  I've found that most of the time you don't need to worry about a little twist.  As your limbs start to bend, and once you get your bow strung, you might see that the bow straightens out as the ends pull against each other.  I have a stave that's partially done with this same thing going on.  I'll take a picture and post it in a little bit.

A "bend" is like a boomerang.  Although hopefully not that severe.  Wink
And with a bend you would likely need to do a heat treatment to unbend it.  But that depends on the severity of the bend and if it will have an effect on the bow.

I agree with walter's point about getting the sides the same thickness.  In general you want to keep things as even and smooth as you can throughout the entire bow.
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joe_meadmaker
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Re: Bend in bow limbs
Reply #5 - Jul 11th, 2020 at 1:45pm
 
And forgot to mention, nice work so far!  That's looking pretty good. Thumbs Up
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joe_meadmaker
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Re: Bend in bow limbs
Reply #6 - Jul 11th, 2020 at 2:13pm
 
Here's the bow in progress I mention two posts ago.  This is a piece of hophornbeam that I started working on, but have been ignoring for more time than I would like to admit.

You can see this thing has a pretty steady twist the whole way through.  It makes me think of a rollercoaster.  But moving out from the handle the twist is going in opposite directions.  So I have no concerns about it.  Once I get this bow tillered down and strung, it will pull itself right into line.  At least that's the hope.  The wood itself will have the final word.

...
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walter
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Re: Bend in bow limbs
Reply #7 - Jul 11th, 2020 at 4:22pm
 
"The wood itself will have the final word." Lol, it do, don't it!
You guys have inspired me to go find a good juniper stave and try to find a bow in it Cheesy
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Morphy
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Re: Bend in bow limbs
Reply #8 - Jul 11th, 2020 at 5:08pm
 
Looking good guys!
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vetryan15
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Re: Bend in bow limbs
Reply #9 - Jul 12th, 2020 at 6:04am
 
Thanks everyone.  I spoke with my mentor (who gave me a nice tongue lashing through text, even though he only taught me knives. Lol) the other night, he said it was a propeller twist, which i then found in TBB vol 1. He also said the main thing is to taper, which i have seen it repeated here. Which i have found to have a couple different thoughts on it. Which in the book, it was just leave it, or build a heat box, and clamp it down and fix it. I really appreciate the information and help.
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Morphy
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Re: Bend in bow limbs
Reply #10 - Jul 12th, 2020 at 9:51am
 
Propeller twist usually isnt a huge issue. Some choose to just tiller it the way it is. For myself I’m very OCD when it comes to bow building and I enjoy heat bending anyways so as long as the bow is conducive to heat bending I’ll just take the twist out. It’s not hard.

Heat boxes are actually for seasoning staves. An easy way to get the twist out is to put the limb in a pipe, close up the other end with a rag and pump steam into the pipe. You can boil it but I always preferred the steam method. You can also loosely wrap the limb in a thick aluminum foil and use that instead of the pipe.

It helps to at least floor tiller the limb first so you can bend it easier. Heres a quick sketch on how i take out twist. Thats a c-clamp by the way. Grin

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« Last Edit: Jul 12th, 2020 at 12:36pm by Morphy »  
 
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Bill Skinner
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Re: Bend in bow limbs
Reply #11 - Jul 12th, 2020 at 7:00pm
 
What Morphy says. 

I've also used a heat gun to heat up small sections of the limb to take the twist out.  That was out by the tip and couldn't be tillered out. 

Same set up as Morphy is showing.  Put the weight on, heat until the limb twists just a little past where you want it to go and let cool.  Take the weights off and see how much spring back you get. 

I use dry heat on osage and red mulberry staves that are pretty close to done.

Steam is for right after they are floor tillered, you can straighten them out, remove twist, add recurves and almost anything you can think of.  It's for moving a lot of wood, a whole lot.
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vetryan15
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Re: Bend in bow limbs
Reply #12 - Jul 12th, 2020 at 8:53pm
 
I must have the terminology wrong, i apologize.  Too much to learn. So i should just try to finish up tillering the bow. And then do the steam bath if i should choose?  Thank you for the information,  for the record the drawing is wayyyy better then anything i can draw.. when i goyt this bow building kit, it came with a dvd called 'rattlestick a self bow tutorial by Gary S Davis, he actually touched on the subject of steam bending the bows into recurve,  and such. I really appreciate the help.
I would talk more about this subject,  but since i dont know poopy, and still learning,  i just keep my mouth shut and listen to advice.  Grin
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Morphy
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Re: Bend in bow limbs
Reply #13 - Jul 12th, 2020 at 11:27pm
 
vetryan15 wrote on Jul 12th, 2020 at 8:53pm:
I must have the terminology wrong, i apologize.  Too much to learn. So i should just try to finish up tillering the bow. And then do the steam bath if i should choose?  Thank you for the information,  for the record the drawing is wayyyy better then anything i can draw.. when i goyt this bow building kit, it came with a dvd called 'rattlestick a self bow tutorial by Gary S Davis, he actually touched on the subject of steam bending the bows into recurve,  and such. I really appreciate the help.
I would talk more about this subject,  but since i dont know poopy, and still learning,  i just keep my mouth shut and listen to advice.  Grin



Sorry if that came off rude bro. Don’t apologize, just thought I would clear that up a bit. If you plan to steam bend the bow I would not take it to full tiller, rather just floor tiller it and then proceed with heat bending. If you finish the tillering and then steam bend you will possibly have to retiller it causing you to lose some weight.

Also be careful if you use the c-clamp method to pad the jaws. A piece of leather against the limb then a shim of wood on top of the leather. You can just glue the leather to the shim so it’s easier to use.

Be aware you have probably around 30-45 seconds after taking it out of the steam to get the full benefit of the heat. So it’s definitely a time sensitive operation. Not difficult by any means but it takes a quick hand to do it with maximum safety.
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vetryan15
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Re: Bend in bow limbs
Reply #14 - Jul 13th, 2020 at 3:16am
 
No worries,  you weren't rude, i figured i used the wrong words. I really appreciate the advice. From my days in knifemaking i learned the hard way  that wood can be marred from the clamps and vice that i use.
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