Author Topic: Couple bow twist issues - how should I handle 'em?  (Read 4948 times)

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Offline kiltedcelt

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Couple bow twist issues - how should I handle 'em?
« on: January 27, 2014, 07:21:11 pm »
Okay, first up is an osage/bamboo blank that I received in trade a couple years back. It was made by David Knight and I believe he used either URAC or Smooth-On for the glue up. The blank glued up with some twist at one end or warped after I received it. I talked with him back after I got it and he suggested just drawing a line straight down the center using something like a laser level or a shadow or other straight edge. This would give a line straight through the handle to either tip. Simply shape the taper of the limbs and you'll take more off of one side that has the twist than the other. I don't like that solution because it doesn't give me any leeway to adjust for twist that might come up during tillering.

What I'm wondering, is if I can steam heat this blank on the twisted end for an hour or more then once it's gone pliable, clamp it to something to straighten out the twist, let it dry, then see if the twist is gone. I'm thinking steam might work better and not mess up the glue joint rather than using a heat gun. Besides, using my heat gun in my apartment tends to blow the circuit breaker anyway, so I pretty much rule out using the heat gun for anything.

Here are the photos. You can see the twist out at the end (probably starts at about halfway between the center and the limb tip), also you can see a slight dishing in near the handle area and finally the grain looks pretty screwy when viewed from the belly. I wouldn't think the grain would matter so much when you're dealing with a bamboo backing but in this case it's obviously caused a twist at that one end.







The second twist issue involves an osage stave I purchased from Osage Outlaw. It has classic propeller twist. Each end twists the opposite direction from the other. Also, one end warps out slightly at the end when you get closer to mid-limb out to the tip. I haven't roughed this bow out yet so I'm totally open to suggestions on how to fix this issue. I've been playing around a bit with staves, having only done board bows up to this point. I'd have liked to have a super-easy stave to work for my first stave bow, but I guess you gotta take whatever you can find when the price is right. I laid this bow out to follow the pattern of the osage flat bow from TBB Vol. 1. I did follow the grain when drawing my layout lines though, so you'll see that the limb on the really twisted/warped end curves way out.

So, for this one, should I cut this out on the band saw following the grain and essentially making this one end be curved? Would I then go ahead and get my taper on the belly then use steam to heat this limb and then clamp it straight? If steam is okay to use for this, at the same time should I go and try to correct the propeller twist before I get into tillering? Right now I don't have a decent bow to shoot at all so I kinda need for either of these two twisty jobs to be fixable so that I can tiller out something to a finished bow so I can start shooting again.

I'd dearly love to have something approaching a trouble-free stave to work on versus something(s) that are going to test my minimal skills with straightening and such. However, I don't really have the cash to spend on more staves so this kinda has to be it. If I can tiller out a good bow from this stave I bought from Clint then I'll be happy. If I mess this up I'm kinda screwed for the next couple months at least, until I can justify spending more money on staves again.

Anyway, here are the photos. Hopefully you can see the propeller twist and that whoop-te-do warpy bit on the one end.






Offline adb

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #1 on: January 27, 2014, 07:29:09 pm »
You can heat straighten the stave, but not the glue up.

Offline kiltedcelt

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #2 on: January 27, 2014, 08:14:12 pm »
ADB - will steam be okay for the stave? I can do steam easy enough - even have a special tube made for using it on a pot of boiling water on the stove. However, dry heat I can't do. As I mentioned, the heat gun will blow the breaker in the apartment continually before I can ever get any significant amount of heat build up.

Offline JW_Halverson

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #3 on: January 27, 2014, 10:14:48 pm »
Gosh almighty, but that is a pretty stave!  The twist is so minor I would ignore it.  If you absolutely HAVE to take it out, wait until you are at the floor tiller stage.  And if you HAVE to use steam, coat it liberally with several layers of shellac BEFORE steaming or else you are going to see a lot of checking of the wood. 

Clint cuts some mighty fine osage!
Guns have triggers. Bicycles have wheels. Trees and bows have wooden limbs.

Offline Blaflair2

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #4 on: January 27, 2014, 10:24:12 pm »
I wouldn't even worry about it. Shoulda saw my first stave! Lol take ur time. Make it wider than u want and once u get it closer where u want it thin it down
Nothing ventured nothing gained

Offline Eric Krewson

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #5 on: January 28, 2014, 09:36:06 am »
If the bamboo blank was glued up with urac (burgundy colored glue line) you can heat it and straighten it. I have done the same dozens of times with no bad effects. I have always used dry heat and never steam so I don't know how steam would effect the glue line.

The prop twist in the stave is minor and could easily be removed with dry heat as well.

Offline adb

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #6 on: January 28, 2014, 10:02:15 am »
Yah, the twist in that stave is minor, and I wouldn't worry about it until the end. If dry heat isn't a solution, steam will work fine.
« Last Edit: January 28, 2014, 12:14:09 pm by adb »

Offline PEARL DRUMS

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #7 on: January 28, 2014, 10:04:10 am »
That's as super easy as staves get man. Its not a board, its the side of a tree. As mentioned, forget the "twist" and go ahead with it. Don't be intimidated, its just wood!

Trust me, there will come a day when you realize just how sweet that stave is. The more you see and handle in person the more you realize what's what.
Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

blackhawk

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #8 on: January 28, 2014, 10:10:16 am »
Why not take Davids advice? He knows what time it is in the shop..and since he glued it up(full width),and seen it in person his advice will be better than anyone else's here IMO...and I agree with what he told ya...easy peasy fix with no messing with heat and risking the chance of messing it up...especially if you don't have a lot of experience with such things(which sounds like it to me,and is apparent)....but I have tweaked glue ups with dry heat before,but I have a lot of experience with a heat gun...i would not use steam..you really can't control the temp or hot it is with steam like you can with a heat gun...and when risking things you better know what your doing with heat and just hiwbhot it needs to get to get it too move,and not getting the glue line its self too hot compromising it

And as far as osage staves go they don't come any better than that...I see nothing wrong at all with that stave....id tell Clint a thousand + thanks for him selling you such a great stave...if that stave makes you apprehensive then set it aside for now,and get some more experience under your belt...a form and heat gun can easily fix and shape that into any desire you want...you can fix,correct,shape,and even temper if ya wanted too all in one shot over a form...do some research on how to build and use a form....

Offline Onebowonder

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #9 on: January 28, 2014, 11:20:52 am »
<snip>Besides, using my heat gun in my apartment tends to blow the circuit breaker anyway, so I pretty much rule out using the heat gun for anything.<snip>

<snip>So, for this one, should I cut this out on the band saw following the grain and essentially making this one end be curved? Would I then go ahead and get my taper on the belly then use steam to heat this limb and then clamp it straight?

<snip>However, dry heat I can't do. As I mentioned, the heat gun will blow the breaker in the apartment continually before I can ever get any significant amount of heat build up.

You mean to tell me that the electrical in your appartment will work effectively to run a bandsaw, but not a heat gun?  Unless you've got one of those itty bitty baby bandsaws; you should be able to just plug the heat gun into whatever circuit is running the bandsaw and you should be fine.  :laugh:


OneBow


Offline kiltedcelt

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #10 on: January 28, 2014, 02:04:14 pm »
Onebowonder - I do have an "itty-bitty" bandsaw. It's not a little toy like one of those bench top models, but pretty close. It's a Craftsman 10" - same thing as the Rikon 10" that Woodcraft sells. It's pretty decent and ballsy enough for cutting out smaller staves. However, it does in fact blow the breaker AND it generates way too much dust, even with a shop vac hooked up. I can run the thing in the "shop" I have in the basement of the apartment building without blowing the breaker there because it's the only thing on the circuit. There's too much crap running on the same circuit in my apartment to keep from blowing the breaker.

Offline kiltedcelt

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #11 on: January 28, 2014, 02:10:47 pm »
Okay guys - I do know this stave is pretty sweet. Fantastic even, especially compared to a seriously gnarly stave I got in trade a few years back that I still don't have the guts to tackle yet. The prop twist is in fact pretty minor and I know a lot of folks who'd leave it in since it probably won't affect string line and might even come out some as the bow is drawn. Also, I'm betting I can correct some for that just by removing a little more wood from the side opposite the twist when it comes to it. Anyway, the main thing that concerned me was the way it curves out at one end. As much as I tried to capture that in the photo I guess it just isn't as apparent to you guys as it is to me. It does curve significantly out at one end. What I'm wanting to know, is should I disregard that twist and cut my limb straight past where that curve is, or should I follow the grain/curve and then heat straighten it when it's at floor tiller stage? That curve is obvious enough in person that it would affect the string line enough that I wouldn't be comfortable trying to shoot a bow with that much of a whoop-te-do at the end of that one limb. So, should I follow the grain on that end then straighten with steam?

Offline turtle

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #12 on: January 28, 2014, 04:54:08 pm »
Looks like the end you are talking about has a side to side bend of 3/4 to 1 inch. Follow the grain and straighten later. When i first started building bows i straightened way worse bends than that by heating over a stove cap in the kitchen and then running outside real fast and bending it in the forks of a tree. Point being that there are other sources of dry heat other than a heat gun.
Steve Bennett

Offline PEARL DRUMS

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Re: Couple bow twist issues - how should I handle 'em?
« Reply #13 on: January 28, 2014, 09:44:53 pm »
Use steam if you can't use your heat gun.
Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.