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Barefaced tightropewalker
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Discussion Starter #1
I understand that metal wall of a drinks can is best material to use to shim a limb (thin, non-compressible). I have always assumed the material was put under rocker area of the limb butt. Is this correct?
Or is it put under cap of the tiller bolt?

I was planning on using hot melt glue to keep the shim in place and perhaps covering it up with electrical tape to protect the riser pocket.

Does this sound ok?
 

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I've not had to do it, but have seen a cheap set of feeler gauges recommended (so you have a choice of thickness). I think placing it under the rocker means it is less likely to shift and possibly double sided tape is more uniform in thickness?
 

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I understand that metal wall of a drinks can is best material to use to shim a limb (thin, non-compressible). I have always assumed the material was put under rocker area of the limb butt. Is this correct?
Or is it put under cap of the tiller bolt?

I was planning on using hot melt glue to keep the shim in place and perhaps covering it up with electrical tape to protect the riser pocket.

Does this sound ok?
you will need a longrod...

send me a PM and we can see about going about this in a logical way :)

feeler gauges are ideal.
 

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Barbarian Tyrant
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I was lectured on another forum by a resident expert that it's not advisable to shim for a twisted limb. It's only meant for bent risers. I shimmed one upper limb on a warf anyway and used some metal flashing, which is like 2 layers of pop cans. I put it under the rocker and has been fine. I think tape or glue would compress over time.
 

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I was lectured on another forum by a resident expert that it's not advisable to shim for a twisted limb. It's only meant for bent risers. I shimmed one upper limb on a warf anyway and used some metal flashing, which is like 2 layers of pop cans. I put it under the rocker and has been fine. I think tape or glue would compress over time.
When shimming limbs, its possible to shim the wrong limb, and make the bow hard to shoot.

For example. due to riser deflex. imagine a bow where the limb pockets were 45 deg rotationally out.

the riser deflex means the grip will be off centre.

The long rod will show where the deflex is pointing, and if you shim the right pocket then the longrod will be central to the string. IE the grip will be central and on plane to the limb pockets

IF that makes sense your doing well :)
 

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Bob, have you ever tried to straighten a limb using hot water and manual twisting? I've never used the technique but it supposedly works in some cases.
 

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I shimmed a twisted riser. I new the limbs were straight. I used a long rod as suggested. Actually it was a bolt chucked in a end mill and screwed into the stab boss. I used the end mill table to figure out where the shins were needed. It worked out and the riser was really tweaked.

I had the string thru the front of the grip. I built out on side of the grip to center the grip fore and aft to make it center shot. I turned out to be a challenge that interested me. It is good a shooter now.
 

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Barefaced tightropewalker
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Discussion Starter #8
Dave, I've had this limb temporarily shimmed before and it works fine. I don't want to mess with twisting it. I now want a more permanent method. Thanks.
 

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I have straightened an old Pro Medalist limb that was twisted in the 6 inches near the top limb's tip......using the hot water Dave mentioned.
Hot - apply pressure--hold pressure on - cool - repeat until straight.
It took several sessions, over the course of a few hours......
It straightened out nicely & made a good shooter out of it.
 

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im not sure some of these modern torsionally stiffened limbs will untwist. but i also wouldnt twist a limb to suit a riser. which is why the top limb bottom pocket symetry test is a great clue to see if its the riser or the limbs that are out.
 

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Mine was definitely limb, could lay it on table & see it's twist.
 

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Bart Harmeling
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I was going to suggest the hot water treatment too. It's worked several times for me and the limbs have not reverted to their twisted ways. I would think that shims may cause an issue as the limb twist may be closer to the tip. The shim might straighten the twist, but the lower are would not be in line with the riser.
 

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yeh I wanted to fix the twist, eliminate it - -not mask it-change it - hide it.
IF it is the riser, then yeh I get that, shimming it to make the riser better.
PLUS, mine was a big ole horrendous wrongly-left banana of a twist sideways, possibly Aidan's is a minor thing.....and a longer gradual mistake.....
 

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Stevelong and Nuthatch:

for glass limbs, yeah, but times are changing...

for example. The Uukha limb. I would hazard a guess that hot water and twisting wont bend the limb.

You could have to take the resins to its TG point (point where the resins go soft, close to the cure Temp)

Carbons come with resins that core at 180Deg C, 120 deg C, 90 deg C etc.
so the TG point will be about 10deg Below what it was cured at.
you might get some movement out of the glues, Possibly cured at a lower temp, and wood cores might "steam bend" a little.

but the Uukha has a one stop cure I assume, and no wood cores or glue lines.

so its never going to budge.

if its a wood cores cross weave carbon limb, the stiffness to torsion, vs the steam bending of a wood core I don't think it will make a difference either.


hope this helps

modern limbs are a little different to older limbs.


not trying to be a smart&&&, just as limb construction gets more complicated some of these neat tricks of the trade wont work... I can see someone twisting like crazy, trying to straighten a spring.
 

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Bart Harmeling
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Sid, The limbs I have fixed were glass limbs. They somehow developed a twist and I was able to remove it. With limbs made of carbon like the Uukha, would any twist be a result of a manufacturing problem? I would think that the same properties that would prevent corrective twisting would also keep them from twisting to begin with.

Not sure what type of limb Greysides has.
 

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Sid, The limbs I have fixed were glass limbs. They somehow developed a twist and I was able to remove it. With limbs made of carbon like the Uukha, would any twist be a result of a manufacturing problem? I would think that the same properties that would prevent corrective twisting would also keep them from twisting to begin with.

Not sure what type of limb Greysides has.
I still wouldn't rule out riser twists.
we have seen some twisted risers that lateral adjustment wont fix.

Its not always the limb.

Id hazard a guess that a solid limb such as the Uukha would return to centre from a side load as much as it would a draw cycle.
 

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Stevelong and Nuthatch:
not trying to be a smart&&&, just as limb construction gets more complicated some of these neat tricks of the trade wont work... I can see someone twisting like crazy, trying to straighten a spring.
SID, c'mon, no one here would accuse you of anything, right?
 

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SID, c'mon, no one here would accuse you of anything, right?
no, im just trying (sympathetic tone) to explain that things are getting complicated.

problem with text is you cant see/ hear my intention.

Im not trying to be a smart&&& just trying to say that there are modern complications to solutions that have worked for years. tried and tested.

I agree. It does straighten limb.

but as top shelf limbs filter through the ranks. this might turn out advise that doesn't work because of the construction of the limbs
 

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Use a hairdryer and heat the limb where it is twisted. Twist the limb the opposite direction that it is twisted just using your hands. hold until limb cools down. String it up and should be straight and will shoot like new. I have straighten several glass limbs with this method never tried on wood limbs
 

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Barefaced tightropewalker
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Discussion Starter #20
Gents, I appreciate all the suggestions. I've sorted this limb before with some simple shimming. It's going to a different riser now and I was looking for a more permanent material and method. I have my answers. Thank you all very much.
 
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