Primitive Archer
Main Discussion Area => Bows => Topic started by: Tommy D on April 05, 2015, 09:04:55 am
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I have a sinew backed osage bow that I am very fond of - a while back I heated in some reflex-deflex and backed it with sinew as it was taking some set (it used to be a self bow). It is also a takedown. The bow is a little snakey and twisted, and of course with the sinew I cannot now heat treat it to straighten/ adjust it at all.
I feel that it is tillered ok and since the string sits to one side, I made this the side for the arrow shelf and rest. I am shooting arrow dynamics trad lite arrows which are normally very forgiving to shoot, yet I can't get them to fly straight or consistently.
I have tried the following:
1) really heavy/ light points
2) longer/ shorter shafts
3) building up the arrow shelf (to ridiculous amounts)
4) changing string height and nock point
And none of these things seem to make much difference.... yet ....
5) if I turn the bow upside down (see picture) (so it looks way off center shot), the arrows fly great.
Is this purely an arrow spine problem, or could it be that the bow prefers to be shot this way? It is a little uncomfortable, but the arrows do seem to zing out of it.
Am I going to mess up the tiller like this?
Do I just accept that this is how it turned out or are there any other solutions I am missing? Perhaps shortening a limb slightly...
Here are some pics...
(http://www.weebly.com/uploads/7/6/0/0/7600230/9555757_orig.jpg)
Bow Right way round, with arrow on shelf
(http://www.weebly.com/uploads/7/6/0/0/7600230/1216080_orig.jpg)
Bow turned upside down, with arrow shot off takedown handle/bow wood joint. Note it sticks out left and looks awkward.
(http://www.weebly.com/uploads/7/6/0/0/7600230/3398830_orig.jpg)
Bow strung - right way round - note string is close to center shot of arrow rest.
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I've had that happen too. I think it is because the arrow slap throws off the arrow.
I am a righty. If the string is off center to the left I usually flip the bow around. It ends up being quieter on release and I get better arrow flight.
Jawge
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It's probably just what Jawge said but for future trys be careful to notice as veiwed from the back not belly the overall lay of the twists and turns of your bow to see better where the more true lay of the string .
The greater percentage of the bow may be twisted to a much differant location then you are seeing at the handle
That gives you a much better pic of what can be going on and one more reason to not shape the handle till the bow is tillered out and shooting
I would just redo the grip and enjoy this one as is
Have fun
Guy
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Try shotting a stiffer spined arrow if you prefer shooting your bow as built. Or just turn it upside down and reshape your handle, if you can.
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Yes, I see that the handle has a rest cut in. Is that correct Tommy?
As Sleek mentioned, in the future, leave the handle full width until at least first stringing and shape it track the string better. Also, leave the nocks full width and cut one end further on both top and bottom nocks. So, in your example you would cut the nocks on the left side further in bringing the string towards the center.
As is can you ove it with a heat gun after coating with some grease?
Jawge
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Jawge does greawe protect sinew when using heat?
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Thanks for the responses guys... as I mentioned the bow is a takedown, so that side was naturally geared towards being the side for the rest/shelf. In addition it was an unbacked bow that I liked, but that had taken set, so I heat treated it into a sort of reflex-reflex shape and added sinew.
Now of course (unless I am mistaken) I can't really heat treat it again with the sinew backing, or unglue the takedown sleeves and line them up again.
One option is that I could probably move the string back towards the center by adjusting the nocks as mentioned by George.
Like I said, arrow flys better upside down, but bow feels uncomfortable/out of balance to hold.
Do you think any of this could be a tiller problem - like the timing of the limbs coming fwds makes it more conducive to being shot upside down?
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Not the best photos but they might help...
Back of Bow
(http://www.weebly.com/uploads/7/6/0/0/7600230/3688837_orig.jpeg)
Belly of bow unstrung
(http://www.weebly.com/uploads/7/6/0/0/7600230/6192204_orig.jpeg)
(http://www.weebly.com/uploads/7/6/0/0/7600230/4873004_orig.jpeg)
Bow strung
(http://www.weebly.com/uploads/7/6/0/0/7600230/7410854_orig.jpeg)
Full draw - 28 inches. Bow is 66 nth
(http://www.weebly.com/uploads/7/6/0/0/7600230/9431446_orig.jpeg)
Unstrung side profile
(http://www.weebly.com/uploads/7/6/0/0/7600230/7446300_orig.jpeg)
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Note it sticks out left and looks awkward.
I'd say that looks correct.
Maybe you have it too close to centre shot when the bow is the "right" way up...
The sticking out left is what the archer's paradox is all about.
Even modern Olympic target recurves (spits on floor) have a little offset from true centre shot.
Out of interest try padding out the arrow pass by 1/4" and see if that improves it. (Unless that's what you meant when you said you tried building up the shelf?)
Del
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Thanks, Sleek. I missed that too. I'd say no on heating a sinew backed bow. Sorry. Jawge
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Tommy,
One more thing...particularly if you cannot turn the stave around.
I once made a yew bow that came from a nearly perfect stave. It was really straight.
The stave was a gift so I want to do the bow justice. I even used calipers to make sure I was removing wood evenly from both sides of each limb.
However, when I strung it the string still leaned to one side. It was leaning to the left. Go figure.
I brought the string to the center by removing wood from the right side of both limbs slowly and with a scraper checking tiller frequently.
The upper limb is stiff mid limb on. Perhaps a little scraping on the right side of upper limb will bring the string to the right; bottom limb looks good. Up to you.
You may not have to touch the lower limb at all to even off the tiller.
Jawge
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Tommy,
One more thing...particularly if you cannot turn the stave around.
I once made a yew bow that came from a nearly perfect stave. It was really straight.
The stave was a gift so I want to do the bow justice. I even used calipers to make sure I was removing wood evenly from both sides of each limb.
However, when I strung it the string still leaned to one side. It was leaning to the left. Go figure.
I brought the string to the center by removing wood from the right side of both limbs slowly and with a scraper checking tiller frequently.
The upper limb is stiff mid limb on. Perhaps a little scraping on the right side of upper limb will bring the string to the right; bottom limb looks good. Up to you.
You may not have to touch the lower limb at all to even off the tiller.
Jawge
I was just thinking about it also and wondered if you could get it to twist a bit by that method
but I actully think there is a good bit that is stiff on both limbs that could be worked on to help bring it around
a little here , a little there and you may get what you need with out much if any reduced draw weight and may even shoot faster
listen to Jawge on this one and see where it goes
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Or just shoot a much stiffer spined arrow. My guess is they go too far right when you shoot?
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the string is not actually lining up like you have it positioned,, yes in the photo it seems to have the string across the handle in a certain way,, but when you actually draw the bow it has a different orientation,,than what it looks like at brace,,, so it shoots better off the other side,, or upside down,,this is quite common for a twisty self bow,, make the handle so you can shoot it the way it likes,, or adjust the tips and take more wood from the arrow side if the bow design will permit,, :)
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Bradsmith - are you saying that you think that it is sort of an illusion that the string lies to one side and actually the bow is more center shot the other way round if you count from the release point. In other words the braced picture is confusing things.
So you think I should make my cut out bigger?
I have my suspicions that the arrows might be too stiff - I shoot them from a much heavier center shot fiberglass bow of 78lbs and they fly dead straight. This bow is about 63lb.
I will try adding really heavy tips to the arrows and seeing if they fly better.
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Your post definitely indicates the arrows are way too stiff.
Don't cut the arrow pass away any more... If arrows can fly out of a 1.5" wide Warbow straight, then you must be able to get 'em flying right.
Del
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OK - a super heavy tip gets the arrows flying straight (but isn't that one of the advantages to a EFOC)...
It does look like the arrows with the lighter tip is kicking off the rest with the fletching going to the left as it leaves the bow (I am right handed)...
I suppose I could try building up the rest way way more than it is and see if the light arrow starts to fly well off this side...
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this is probably a dumb suggestion but it may help...
try shooting a couple off the other side of your hand with the bow held normal top side up ala Lars Anderson's way of shooting..
see if they fly straighter...
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I don't believe you mention the arrow spine (sorry if I missed it), but if I were to guess what might shoot well out of the 78 lb centershot bow, I would think maybe 80-85 spine...a bit more than the draw weight is typical. Non-centershot bows usually start with less than the draw weight because of the need to flex more, so for 63 lbs something like 55-60 might be better. So, you might be off by 25 lbs of spine, which would explain why the super heavy points help. I would keep experimenting with arrow spine for a while before messing with the bow. You could sand a few shafts down - you will get the fastest results by sanding in the middle. Good luck!
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yes I think the braced pic may not be reflecting the real orientation of the bow when draw,,
lighter spine arrows will help,, but if the bow is shooting better off one side it will probably continue to do that with any spine arrow
I cant suggest making the cut out bigger,, I cant see from the photo if the handle would accommodate it,, but maybe file it rounder or slightly reduce where the arrow comes across,, :)
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Is the arrow on its way silently...with barely a whisper? Jawge
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I made a set of test arrows. Six arrows 5# apart in spine, no fletching. They work great for this kind of problem. Start with the stiffest arrow and work your way down until the arrow goes straight. Eliminates a lot of guesswork.
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Paper tune, brother! I just built my first set of Red Osier Dogwood arrows, and shot them through paper today without fletching. I feel like I learned volumes about spine, arrow weight, and what side of the arrow needs to face the bow. It's incredible how much of a difference putting the arrow a few fractions of an inch further or closer to center (in my case, by switching between my new bow and old bow, one of which is nearly a center shot) will affect the spine you need to shoot.
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You can't adjust your bow really not.
you can't shoot it upside down because the new lower limb will feel too much strain and will definitely mess up the tiller(assuming it's spot on the 'right' way up!).
Arrow spine, arrow spine, arrow spine is your problem! Low 60's bow, non centershot....I would try around 50 - 55# spine arrows with 100 - 125 gn points at 28 inches long.
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Thanks for all the suggestions.
My flu flu arrows fly great!!