Primitive Archer
Main Discussion Area => Bows => Topic started by: Tommytinker on July 08, 2014, 01:01:16 pm
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So I'm working on this sinew backed hickory static recurve. 51 1/2" nock to nock.
I'm fairly new to this world, I've finished only five bows. This project is some what of an experiment. incorporates several features that I am completely new including sinew backing, recurves, brush nocks and horn tip overlays and laminations.
I used dry heat to flip the tips resulting in some pretty major cracks (some might say breaks) on the belly side, more then half the way through. I came very close to scrapping the whole thing but decided to sand off the effected area and glue on laminations and build up brush nocks.
I must also confess I had a moment of madness and lay down a layer of black fibreglass on both sides of the recurved area or extra "security"! Don't judge me!
At this point I thought I may as well use this Frankenstein's monster as a learning curve for sinew backing.
I lay down two layers of red deer leg sinew, let it dry for several weeks and covered it with black water snake skins.
I've got her bending fairly evenly (too my un-trained eye). She's pulling 35# @ 18" and I'm aiming for 40 - 45 @ 25"
She's only taken 1 1/2" of set which is a record for me.
I'd really appreciate some advice on the tiller and where to go from here.
Is pulling such a short bow to 25" stupid?
Any input or advice would be great!
Images to follow.
Tommy.
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(http://i1295.photobucket.com/albums/b633/tommyz4/Mobile%20Uploads/image_zps4ff9284f.jpg) (http://s1295.photobucket.com/user/tommyz4/media/Mobile%20Uploads/image_zps4ff9284f.jpg.html)
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(http://i1295.photobucket.com/albums/b633/tommyz4/Mobile%20Uploads/image_zpsf89a199c.jpg) (http://s1295.photobucket.com/user/tommyz4/media/Mobile%20Uploads/image_zpsf89a199c.jpg.html)
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thats a bit much/short for hickory. next time you want to recurve hickory you should boil it instead.
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(http://i1295.photobucket.com/albums/b633/tommyz4/Mobile%20Uploads/image_zps1f073e8c.jpg) (http://s1295.photobucket.com/user/tommyz4/media/Mobile%20Uploads/image_zps1f073e8c.jpg.html)
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Bowman, I know this us a badly designed/executed bow. Still been a fun experience! You live and learn!
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Bowman, I know this us a badly designed/executed bow. Still been a fun experience! You live and learn!
yup
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With sinew your probably alright. Id suggest getting the last half of each limb bending more. Your taking set mid limb and in because its flat from there to your recurve build ups.
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Thank you for the advice. I can see that now you say it, I'll post mor pictures
When it's finished (if it doesn't explode!).
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It's not badly designed at all. Just get your outer limbs coming around more and trim the excess off your brush nocks.
You can probably almost halve the bulk while still maintaining the same outer dimensions.
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Thank you for the encouragement Pat.
If it turns out well, there's one little thing that's going to really bug me!
The sinew finish is far from flat, I didn't realise how bad it would look until I stuck the skins on.
Has anyone had success removing skins from sinew? If so, how?
If I add another layer of sinew to build up a smooth crown, will this adhere to the surface after removing the skins? I used titebond bond III for the job and for gluing the skins on...
Again, any advice much appreciated!
Tommy
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You won't be able to save a skin that is glued down, probably but you can sand the sinew/Titebond and add more.
Another tip if I may...hickory bends very well with steam but not well with dry heat. When using a heat gun I have either had recurves crack from getting too dry or the bend didn't stay in some that weren't heated enough.
Lots of firsts for you with this bow. 8) Nice job so far. Listen to these guys. They will set you straight.
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Thanks Pat B.
I didn't think I'd be able to save the skins. I've got a matching set of spitting cobra skins which I'll use only if I'm really happy with the bow.
I haven't done much work on the brush nocks yet. I'll trim them down as much as possible.
I've noticed that there is a problem with tracking. Each recurve is twisting in opposite directions to each other.
Should I correct this now? Or after I've finished the tiller. I guess it's going to have to be corrected by wood removal as heat will spoil the sinew?
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How much twist? Post a pic if you can. Also post a pic where it crosses the grip.
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It seams fine as brace. But pulled to 18" I'd say about 1/2" in each direction. Is this going to prove to be a nightmare?
I'll post pics when I can.
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Its probably fine then. Is the thickness EXACTLY the same from side to side on each limb? If you don't trust your fingers, measure it. Ive made a few statics and keeping them dead straight is almost impossible.
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Do you have a tillering Gizmo? Sounds like the limb thickness is uneven if it twists as you draw. You can use the Gizmo down both sides of each limb and it will show you where to remove wood to eliminate the twist.
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I will check when I get home from work. I have digital callipers, I'll use them.
If both tips twist, but in opposite directions, so the string intersects the middle of the bow. Is this still a problem? Or would the twist put strain on the bow and course future problems? (Note - I'm not saying this is the case on my bow, I'll have to check when I get home)
Thanks.
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If the string stays on at full draw, its fine in my opinion.
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Don't be too afraid to twist the tips into line manually.
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When you say manually, do you mean no heat, no wood removal, just brute force?
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I'd check the thickness, if it was good maybe there's more sinew on that side. Just give em some pressure and teach em where they're supposed to be.
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Screw work. I want to go home and play with this thing now!
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When you say manually, do you mean no heat, no wood removal, just brute force?
Yes. It actually rarely needs much force. The smallest amount of twist looks drastically out of line over the length of a bow when it has recurves
Try holding one recurve between your feet and torqueing the other end by hand. You can sight down the bow and see how little force it will take to even twist it past straight.
Make sure you hold the string on the recurve while you do this.
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Once u make your string grooves it may help hold it center as well depending on how deep u make them