Author Topic: An impossible situation  (Read 1630 times)

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Offline NruJaC

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An impossible situation
« on: October 14, 2012, 10:30:57 pm »
So I've been working on my xmas trade bow, and reached something of an impossible situation. I was making a maple backed maple r/d, and I floor tillered the core, and then glued the whole thing up with 3.5" of reflex, and 2" of deflex (expecting it to keep 2-2.5" of reflex, and 1" of deflex -- which should balance out once the bow takes a little set). Of course, when the bow came out of the form, it was totally stiff, so I went back and floor tillered it again. Except this time I had to go through a ton of wood (by mass, I lost about a third of the weight of the bow), and the bow kept taking on more and more reflex. See, when it came out of the form it still had 3" of reflex, which was a bit higher than I was hoping for, but still manageable. But it only had 1/2" of deflex, which is astoundingly low. But as I floor tillered, the bow kept gain reflex -- and it's now up to a whopping 5".

Yea, you read that right, 5" of reflex, a full 1.5" more than I even attempted to glue in.  :o

What on earth is going on, and can I still salveage this bow? I worked the width the of the bow down some because I thought I had plenty of mass to work with -- apparently not!

So all said, I doubt this will be my trade bow, it's gone off the rocker. But this is also the first time I've had a project go so far astray -- I want to see if I can reign it in and make a shooter out of it. :embarassed:

Full specs:
68" long (I assume it will be 67" ntn when I get around to cutting in nocks)
Bendy handle, but has a very slightly narrowed and thicker handle section -- I expect it to still bend through the handle, but not arc of the circle.
1 3/8" for about half of each limb, then a smooth taper to 1/2" tips

The stave is floor tillered, and I could probably brace it at this point. Both limbs seem to bend smoothly.

Help?

I'll post pictures if anyone wants them.
Arjun from Reston, VA

Offline lostarrow

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Re: An impossible situation
« Reply #1 on: October 15, 2012, 01:00:05 am »
Pics would probably help a bunch.

Offline NruJaC

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Re: An impossible situation
« Reply #2 on: October 15, 2012, 08:11:55 am »
Here's an unbraced pic. More pictures will have to wait till I get home from work. I'll brace her tonight and see what she's pulling.



Edit: Whoops, didn't notice that the pic failed to load. Fixed!
« Last Edit: October 15, 2012, 08:39:27 am by NruJaC »
Arjun from Reston, VA

Offline Onebowonder

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Re: An impossible situation
« Reply #3 on: October 15, 2012, 10:34:54 am »
It looks like it wants to be a gull wing bow...

Offline blackhawk

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Re: An impossible situation
« Reply #4 on: October 15, 2012, 11:14:41 am »
I wish my staves wood do that when I tillered, but for some reason mine go the other way..lol :laugh:

Was your wood dry? Boards? From air dried staves? Did u use a hotbox? Glue? Need more data please.
Oregon.. They got all the good wood...EXCEPT the best...OSAGE ;)

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Offline NruJaC

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Re: An impossible situation
« Reply #5 on: October 15, 2012, 11:27:33 am »
Blackhawk, wanna trade?  :laugh:

I can't speak for the backing because it was purchased online, but the core was a board from a hardware store that happened to have great grain. Got caught in a rainstorm on the way home so I guess the board got a little wet? That was 6 weeks ago though -- I expect that the board would have come back to equilibrium in that time. Glue was gorilla glue's wood glue.

Even floor tillering this stave has been a challenge -- the profile kept changing! In a way though I'm getting kinda excited about this bow. It's turning into a real challenge.
Arjun from Reston, VA

Offline k-hat

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Re: An impossible situation
« Reply #6 on: October 15, 2012, 11:46:09 am »
I don't know much about r/d bows, but i would think that where you removed the wood from could make a difference, especially with the amount you removed?  It seems that if your thinning the deflex part, then there is less wood to hold the back in deflex, so it springs back. 

I need to know either way because i have plans for some r/d staves in the future :)

Offline NruJaC

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Re: An impossible situation
« Reply #7 on: October 15, 2012, 11:51:37 am »
The opposite, I've had to mostly remove wood from the reflexed portion of the limb. The deflexed region near the handle is close to the original thickness.
Arjun from Reston, VA

Offline k-hat

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Re: An impossible situation
« Reply #8 on: October 15, 2012, 12:35:42 pm »
Well there went that then   ;)  good thing i had that disclaimer ::)

Offline Stringman

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Re: An impossible situation
« Reply #9 on: October 15, 2012, 02:06:25 pm »
I would like to see this bow with a little tension on the string.

Scott
Scott
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walk softly, and carry a bent stick...

Offline NruJaC

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Re: An impossible situation
« Reply #10 on: October 15, 2012, 06:17:53 pm »
Woah, this bow has some real early draw weight. I barely got a tight string on her.

So here's the bow on a tight string and on the tree. Note the clamp. She's just as happy strung backwards as forwards, and trying to get her on the tree caused her to flip. On the plus side, I found an easier way to string her.  O:)



And here she is at a whopping 43# @ 7". No, that's not a typo.



Picture is a little crooked, so I'm not yet sure if the left limb is weaker than the right limb. I always have to flip the bow to see. This tree is also really good at optical illusions (cause of the open hallway behind the right limb), which makes the left limb look weaker regardless of the bow. I'll get her the other way and take more pictures in a little while.

EDIT: Here's the pic with the limbs swapped. The string feels looser and the bow didn't try to flip on me, so no clamp this time.

« Last Edit: October 15, 2012, 06:24:52 pm by NruJaC »
Arjun from Reston, VA

Offline NruJaC

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Re: An impossible situation
« Reply #11 on: October 15, 2012, 07:29:43 pm »
Ok, tweaked the tiller some. The left limb has gone up to 5.5" of reflex, while the right limb has gone down to 4.5". *sigh*

Thankfully both limbs are still balanced in the center half of the bow. It's just that finicky outer half that's causing problems. So given the difference in starting reflex, the following tiller looks pretty good:



I'm gonna work on dropping the draw weight some, and getting her strung at a real brace. Let me know what you guys think of the tiller.
Arjun from Reston, VA

Offline blackhawk

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Re: An impossible situation
« Reply #12 on: October 15, 2012, 08:13:55 pm »
I have no personal experience in using gorilla glue in bow building, but I've heard guys say to stay away from it. So my concern isn't your tiller, which is looking ok so far but ur not pulling very much yet, but I'm curious to see if the glue holds up to that much tip travel.
Oregon.. They got all the good wood...EXCEPT the best...OSAGE ;)

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Offline NruJaC

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Re: An impossible situation
« Reply #13 on: October 15, 2012, 08:16:26 pm »
Yea, I remember the discussions on it from way back in the day. But the wood glue is different than the usual gorilla glue, and seems pretty similar to TB3 and Elmer's wood glue. I did a small bend test before I tried it and the wood broke before the glue did so I felt pretty safe using it in a bow.
Arjun from Reston, VA

Offline fishfinder401

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Re: An impossible situation
« Reply #14 on: October 15, 2012, 08:23:52 pm »
whats the intended draw weight and length?
warbows and fishing, what else is there to do?
modern technology only takes you so far, remove electricity and then what