Author Topic: Small twist in a stave  (Read 9403 times)

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SimonUK

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Small twist in a stave
« on: January 01, 2008, 07:14:25 pm »
Hi all

I'm wondering whether I should try to do anything about this small twist in an elm stave.  My bows have a habbit of snapping during tillering so I must be doing something wrong.

In the picture the back is facing up. It might be difficult to see, but the back twists towards the camera at midlimb then straightens up again. there's also a bit of reflex at the same position.  I think it's too short to try steaming it straight.

I don't want all the tension building up on the opposite side of the back. Should round off the back less on this side and more on the opposite side, to make the bow bend slightly sideways relative to the grain? Or just build it as if it were straight and hope for the best? Thanks.

« Last Edit: January 01, 2008, 08:33:18 pm by SimonUK »

Offline mullet

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Re: Small twist in a stave
« Reply #1 on: January 01, 2008, 07:44:19 pm »
    Simon,Normaly I wouldn't worry about a twist that small. But the wieght you guy's build bows need's the experiance that I don't have. Any other bow ,I would take wood off equaly in that area and see if it straightens up at full draw. I believe taking the heat gun to an area that small in the working part of the limb contributes to failures.
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SimonUK

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Re: Small twist in a stave
« Reply #2 on: January 01, 2008, 08:30:55 pm »
Thanks Mullet. It's probably not going to be very heavy - maybe 75 or 80 lbs, about 80 inches long and with the usual longbow width:depth ratio (about 4:3).

duffontap

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Re: Small twist in a stave
« Reply #3 on: January 02, 2008, 02:10:40 am »
Simon,

I would go with Mullet's advice for sure.  At 75-80 lbs. you should be ok.  Take your time tillering and you shouldn't have it blow up on you. 

      J. D.

SimonUK

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Re: Small twist in a stave
« Reply #4 on: January 02, 2008, 09:26:50 am »
Thanks JD. Good to see you back again.

Simon

Rich Saffold

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Re: Small twist in a stave
« Reply #5 on: January 02, 2008, 11:40:24 am »
Simon,All the elms I have used were very strong in tension and handled the poundage you want and twist you show here. In the low humidity here, it's a favorite..Well since we can't go out and cut high altitude yew in the local suburbs...

Rich

SimonUK

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Re: Small twist in a stave
« Reply #6 on: January 03, 2008, 11:17:19 am »
Thanks Rich. I know how you feel ...oh to be living in the alps.

SimonUK

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Re: Small twist in a stave
« Reply #7 on: February 01, 2008, 11:26:13 pm »
I made exactly the same mistake as I did with my last reflexed stave: too much floor tillering.  I got a weak area near that twisted part. Then I had to take a lot of wood off the rest of the bow to make it bend evenly.

So the draw weight at the moment is only 60 lb and I still have some tillering to do.  It's 83 inches long - how much would I need to shorten it to bring the weight up to about 75 lbs?

It had about an inch of reflex at the start, now it's completely straight.  Here are some pictures:

Before tillering (back is to the left)



Full draw, trying not to scrape the ceiling.  Any advice on the tiller? The upper limb is too stiff I think, but should I continue tillering, or just shorten the lower limb and re-position the handle? Thanks.


Offline D. Tiller

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Re: Small twist in a stave
« Reply #8 on: February 02, 2008, 02:13:57 am »
If you are at full draw then thats it for that bow! Now next time I think I would be getting the upper limb to bend a bit more on the last 3/4 of the limb. Just looks a tad stiff to me.  You could pike it a bit and have some more to work with but for a firs bow this looks good. Try and shoot it and see how it works.

David T
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Offline Asiertxu

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Re: Small twist in a stave
« Reply #9 on: February 02, 2008, 05:28:41 pm »
Hey Simon!

That´s a fine looking bow and tiller mate!!..8) REALLY NICE in my opinion.

If you want a faster and heavyer bow, you can allways shorten it a bit (one to two inches from the tips in both limbs)... :) ;)...

Now, you only have to fit some nice english style horn nocks on it and ready to shot!!

Thanks for share Simon..

Cheers...

Asier.
//Asier from "Basque Country" Spain.

Offline Asiertxu

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Re: Small twist in a stave
« Reply #10 on: February 02, 2008, 05:30:41 pm »
Oh,

Regarding to the twist on that stave, then what the others have allready said.
You sould be O.K. at that lenght and draw weight.

Cheers..

Asier. 
//Asier from "Basque Country" Spain.

SimonUK

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Re: Small twist in a stave
« Reply #11 on: February 02, 2008, 06:11:26 pm »
Thanks guys.  I'm quite disappointed with the low draw weight - welcome to the world of bow making!  I think I will shorten only the weakest limb, it's my best chance of getting up to 75 lbs.

Offline heavybow

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Re: Small twist in a stave
« Reply #12 on: February 03, 2008, 03:56:11 am »
Simon nice picture you forgot to smile. Marlon ;D

Offline Marc St Louis

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Re: Small twist in a stave
« Reply #13 on: February 03, 2008, 05:06:51 pm »
Depending on your draw length you could shorten that bow by up to 8", 4" from each end. You would still get a 31" draw from that lengh, maybe more. Elm is very strong in tension so you don't have toworry about it breaking on you. I would also be tempted to take a heat gun to that one and temper the heck out of it
Home of heat-treating, Corbeil, On.  Canada

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Offline Yeomanbowman

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Re: Small twist in a stave
« Reply #14 on: February 03, 2008, 07:49:24 pm »
Hello Simon,
Don't forget about pyking as well as shortening.  Jaro takes his tips down to sub 1/2" with dense ash/elm (I think?), but 1/2" maybe safer .  The outer limbs look a little bit chunky, do you leave them a tad thicker for tillering and slim them down before horning?
Lovely bow BTW.
Jeremy