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thumbless stringwalker
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Discussion Starter · #1 ·
Hi,
Just realize that top ILF fitting groove have some deformation.



Do not why it happens.
What do you think?
Thanks
Martin
 

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I've had that happen with an older ali riser. I believe it is due to the bounce in a limb pocket ILF limbs can have. This was made in very soft ali, and I had a nock failure and effectively a dry loose. Fortunately for me it had removable pockets so I simply changed them.
If you have a crack starting I personally would retire the riser because I am cautious. If it is just deformation I would watch it while tracking down my new riser and then retiring this one!
 

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I agree with Mike. There should be no pressure there unless there is binding of the dovetail due to the limb bold being backed out too far. The only other thing that I can think of that could cause this is a broken string allowing the limbs to hyperextend beyond brace.
 

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Mike and Sid,

My understanding is the ILF dovetail assembly should not be subject to any major forces at brace or during the draw. On Martin's riser the ILF fitting from the limb has been bearing on the bottom of the ILF slot as shown.

Mike, as you say, if the limb bolts are way out there could be a gap between the bearing surface on the limb bolt and the top of the slot at the bottom of the limb butt. I have seen limbs that had the slot cut too deep which also causes the ILF fitting to take all the inward (toward the handle) forces. This may be Martin's problem. Or the Riser could be out with the ILF slot to Limb bolt distance too long.

Martin, Please check different sets of limbs on your riser. There should normally be a tiny gap between the ILF slot and the ILF fitting. Whereas you should be able to feel a solid connection between the slot of the limb butt and the limb bolt.

Rasyad
 

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thumbless stringwalker
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Discussion Starter · #9 ·
Thanks for the answers.
Rasyad,
Do you mean that limbs should seat on (press) tiller bolts?
According to what I have read for years limbs should seat on ILF fitting. Am I wrong?

Thanks
Martin

I have been thinking......... why only top limb ILF.
Could it be a problem caused by stringwalking?
 

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Hi Martin,

This is why I addressed Mike and Sid as they should know. If you are correct and the seat should be on the ILF fittings then I would suggest there is a hardness or materials problem with your riser. Wearing through the anodizing is one thing, deforming as yours has is another. As to top limb pocket only....I would measure the distance between the lomb bolt and ILF slot top and bottom, as well, measure the limbs. I don't think stringwalking alone on a reasonably well tuned bow should be able to create the problem you have.

Rasyad
 

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We had a string failure on a cast riser. And the limb dovetail flange simply pulled through the casting tearing a circular lump out the riser.
But thats not what i think is happening here.
In our opinion the ilf system is designed to take all the inward forces of the bows closure on the dovetail.
This would be a sheer force which the dovetail being steel can take easily.
If you look at the hds system in the hoyt setup. The dovetail in the riser is cut out of some sort of steel.
If the load was taken on the limb bolts. The pressure would have the possability of bending the bolts especially when yhe bolts are fully out.
If the limbs are wound all the way in. Then it could be a case of some brusing from the lack of flat on flat action.

But to recite a old story.
We put over 5000 dry fires through a riser. Trigger shot at 28".
I can say that the riser was wrecked. The limb bolts had ovalised the threads. The bolts that held the limb pocket on were almost stripped. And the dovetail slot was about 1mm bigger in every direction. The forces in a dry fire will wreck a riser if repeated.
String failure, nock failure, and human error all lead to problems. I dont think this is a wound out issue. It simply could be lots and lots of shots from with light arrows.
Im not accusing Martin of abuse. Just the possability of some wear and tear.

Ill see if i can get some photos together of some beat up slots.

I can also show you what taking the weight on the limb bolt looks like on the limbs after 50000 shots. There is one riser that doesnt/cant take the weight on the dovetil due to the material its made of. And it has an effect on the limb.
 

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here is a new set vs old set of limbs where the weight had been taken on the limb bolt.

as you can see the brusing on the carbon faces, and the mushing of the spot we put on the top limb...

 

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so i can see a point where if the limbs are fully wound in. you would be putting all the weight on the upper edge of the lip on the slot in the riser. fully out and this would happen at the lower edge of the limb.
mid position would put flat on flat. (least peak PSI on the ali)
 

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sorry for the poor picture... but here is what i think it is...

if im right, then all that has happened is a little bit of wear and tear, a little bit of work hardening in way and it will be just fine.
 

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Could it be a problem caused by stringwalking?
could be a little bit of chatter from string walking, but again, i wouldnt worry about it personally.

if your bolts are fully in then its an angle/pressure point thing that comes about with ILF and its adjustability.

again, with all internet Diagnosis, be aware, you have the evidence, we have all the assumptions. :) So i could be wrong.
 

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thumbless stringwalker
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Discussion Starter · #18 ·


sorry for the poor picture... but here is what i think it is...

if im right, then all that has happened is a little bit of wear and tear, a little bit of work hardening in way and it will be just fine.
Good point Sid.
I get this riser used and I'm not sure if deformation is new or old.
When I reduce preload, I always check clearance on the bottom of ILF slot for at least 0,1mm (paper).
I remember that some time ago one shot sound like a gun shot....... just looking for a reason.
May be previous owner shot light arrows, I could not shot under 9gpp.
Thanks
Martin
 

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Funny clicks and noises in the first shot are usually the limbs seating in to place. Most times its only a very small movement. So no change to brace height or tiller.
But just a loud click as it seats into its correct position.
 

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sorry for the poor picture... but here is what i think it is...

if im right, then all that has happened is a little bit of wear and tear, a little bit of work hardening in way and it will be just fine.
This is just my opinion, but I'm not sure that's what is happening in this case. The areas of abrasion don't correspond.
 

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