# How are ILF limbs supposed to fit?



## omega_archer (Aug 25, 2008)

Here is my recent experience with ILF limbs and I am wondering if others have had similar fit experiences and how they fixed them if at all.

I just bought some Samick Universal limbs to go on my old Hoyt Radian. With the limb bolts backed all the way out, the limbs were so tight on the riser that they wouldn't come out unless 2 people pulled very hard. I noticed the following:

- With the limb bolts backed all the way out, the limbs were not able to pivot enough to touch the face of the limb bolt (the limb looked like it was floating in limb pocket) but was really tight. I believe that the bottom part of the limb bolt was putting pressure on the back side of the limb keeping it tight. 

- When I compared the Samicks to my old Hoyts, I noticed that the slots that go into the limb bolts are about 0.060" longer (measured to the back edge) on the Samicks.

- The width of the Samicks are about 0.060" wider. They fit into the pocket but it's tight.

- The detent ball on the Samick and Hoyt limbs don't actually get to the detent. The riser only shows wear at the leading edge of the groove/ball receiver. I confirmed this with calibers that it's about 0.40" short from going in and about 0.125" of the "pad" is extended from the riser. When I put the limbs into the slot without using the detent feature, the limbs go further into the pocket. Are they supposed to fit this way or should the ball atually sit in the detent hole like it was probably designed to do? I never questioned my old Hoyt limbs

I know many have sanded the slots to get a better fit and I did this initially. Do you all modify the limbs further (sanding the edges etc) to get the "proper" fit?

BTW: when I turned the limb bolts to make sure the limbs were contacting the pad, the bow was a lot quieter as you would imagine. Are limb bolts not designed to operate all the way out (lowest weight setting)?

Thanks in advance, the info on this forum has been great!


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## Dave T (Mar 24, 2004)

An interesting post in light of the other thread where everyone bashed Alternative Services for their warning about this very sort of situation.

Curiouser and curiouser!
Dave


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## omega_archer (Aug 25, 2008)

Dave T said:


> An interesting post in light of the other thread where everyone bashed Alternative Services for their warning about this very sort of situation.
> 
> Curiouser and curiouser!
> Dave


Dave T, I was going to post this in that thread, but since my riser is 15+ years old, I didn't think it applied so I started a new one. When I bought the setup way back, I never even thought to look since they were both Hoyt products but now I'm thinking my ball never got to the pocket. 

heres a pic with the detent system lined up. You could see the wear marks where it meets the riser and is consistent.


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## Seattlepop (Dec 8, 2003)

Dave T said:


> An interesting post in light of the other thread where everyone bashed Alternative Services for their warning about this very sort of situation.
> 
> Curiouser and curiouser!
> Dave



If only that were the case. This is not what ALT was warning against. Read the warning and you should see that ALT is directly addressing the change in reflex/deflex angle on the Helix/Nexus and says breakage may occur because of the additional stress put on the limbs due to this change in "alignment", which, as far as I can tell, has nothing to do with change in reflex/deflex. 

"A particular case in point is the current range of Hoyt risers where the pivot point has now been moved back in line with the dovetail location. *This pivot point on most other bows is on the leading edge of the pocket*. This has resulted in some cases of poor fitting and non-alignment of limbs and in extreme cases even breakage due to the increased strain on the limbs."

Also, if you would look at the bolded sentence in ALT's warning (emphasis added), I believe ALT is saying that very problem Omega is describing (and which Joe T refers to in the other thread) is how "other bows" do it and is the norm.


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## 6cuda6 (Nov 10, 2008)

I think sanding the limbs WOULD NOT be the best idea onless it's done by a machinest.....if the limbs are not perfectly equal they will not deflect staight. I would be inclined to make the adjustments on the riser as limb alignment is held in check by the bolt and button.

I would suspect the best is to replace the riser with something more current......????


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## omega_archer (Aug 25, 2008)

6cuda6 said:


> I think sanding the limbs WOULD NOT be the best idea onless it's done by a machinest.....if the limbs are not perfectly equal they will not deflect staight. I would be inclined to make the adjustments on the riser as limb alignment is held in check by the bolt and button.
> 
> I would suspect the best is to replace the riser with something more current......????


I do have experience machining and a technical background which of course isn't always a good thing. I would think that the main guide and support is the pivot at the detent and the slot for alignment. Unless I'm missing something, the back end (legs of the slot) don't seem like they are a critical piece of the puzzle.


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## 6cuda6 (Nov 10, 2008)

omega_archer said:


> I do have experience machining and a technical background which of course isn't always a good thing. I would think that the main guide and support is the pivot at the detent and the slot for alignment. Unless I'm missing something, the back end (legs of the slot) don't seem like they are a critical piece of the puzzle.


I was thinking you might look at norrowing the sides of the limb as the depth of the button and slot look consistant from the pic.....odviously you have the skill and the tools to do it...i would say go for it...heck if you build a jig you could do this mod for other that i suspect have the same issue...


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## omega_archer (Aug 25, 2008)

Seattlepop said:


> If only that were the case. This is not what ALT was warning against. Read the warning and you should see that ALT is directly addressing the change in reflex/deflex angle on the Helix/Nexus and says breakage may occur because of the additional stress put on the limbs due to this change in "alignment", which, as far as I can tell, has nothing to do with change in reflex/deflex.
> 
> "A particular case in point is the current range of Hoyt risers where the pivot point has now been moved back in line with the dovetail location. *This pivot point on most other bows is on the leading edge of the pocket*. This has resulted in some cases of poor fitting and non-alignment of limbs and in extreme cases even breakage due to the increased strain on the limbs."
> 
> Also, if you would look at the bolded sentence in ALT's warning (emphasis added), I believe ALT is saying that very problem Omega is describing (and which Joe T refers to in the other thread) is how "other bows" do it and is the norm.


Seattle, If you look at the wear marks on both risers, they are in identical positions. I guess the question is wear does Samick want the pivot point to be? When I adjust the limb bolts in a full turn, fit is good with the Samicks or at least as good as they were with the Hoyt's. I don't believe either limb is sitting in the hole for the detent. I guess the question is whether this is a problem or not.


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## omega_archer (Aug 25, 2008)

6cuda6 said:


> I was thinking you might look at norrowing the sides of the limb as the depth of the button and slot look consistant from the pic.....odviously you have the skill and the tools to do it...i would say go for it...heck if you build a jig you could do this mod for other that i suspect have the same issue...


Thinking about it some more, I think I may need to modify the actual length of the slot because it seems to be bottoming out on it before the detent falls in since the limb goes in another 0.05" when not in the detent slot. 

On your limbs, do you see the wear marks in the bottom of the depression?


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## Seattlepop (Dec 8, 2003)

omega_archer said:


> Thinking about it some more, I think I may need to modify the actual length of the slot because it seems to be bottoming out on it before the detent falls in since the limb goes in another 0.05" when not in the detent slot.
> 
> On your limbs, do you see the wear marks in the bottom of the depression?


When I measure your limbs on my screen (however accurate that is) I get the same distance on both limbs from the center of the detente button to the bottom of the "U" (6mm). This should mean that the detente button falls in the same location for both. 

However, I see that the "U" extensions (don't know what to call them) are longer on the left limb. This would make a difference on where the limb butts up against the bottom of the limb-bolt cap which would be farther back into the limb pocket in this case. That would affect the angle of the limb as it leaves the riser. If I'm correct, the limb on the right could have slightly deeper cuts where it "pivots" on the edge of the riser.


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## Seattlepop (Dec 8, 2003)

*visual*

This is what I'm talking about - the limb pictured on the right would be the red line...

View attachment 499151


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## Dave T (Mar 24, 2004)

Seattlepop,

You seem to take exception with my light hearted, tongue in cheek post. I would delete it but the time for that is apparently past. So...I here by officially and formally retract everything I said in this thread. Please forgive me my frivolous frame of mind.

Dave


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## 6cuda6 (Nov 10, 2008)

I think SeattlePop might be on to something here.......

If the tails are in different places against the post it will change the anchor as well as how the limbs pivot against it......

Do you have access to machinest molding compound [play dow might even work]...i would take an imprint of the limb pocket and compare it to the original factory supplied limbs allowing verification of the limb design/placement...then compare it to the new limbs and see the differences....[i think there was a post on here somewere about the differences and how it was over come?]


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## Seattlepop (Dec 8, 2003)

Dave T said:


> Seattlepop,
> 
> You seem to take exception with my light hearted, tongue in cheek post. I would delete it but the time for that is apparently past. So...I here by officially and formally retract everything I said in this thread. Please forgive me my frivolous frame of mind.
> 
> Dave


You're right, I need to read with a little less tongue and a little more cheek!


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## omega_archer (Aug 25, 2008)

Seattlepop said:


> This is what I'm talking about - the limb pictured on the right would be the red line...
> 
> View attachment 499151


Hey Seattlepop,

What appears to be going on is something like this. The cross section is the limb.

If you look at the sketch of my configuration with the limb bolt extended out. My limbs as they are do not hit the top retaining nut. There is visible space as shown, which is why I started to look into this more. You can actually visualize how limited the movement is at this position. The slot in the limb isn't parallel with the the shaft and has less movement. Also the detent will only be able to tilt so much until it contacts the groove limiting it's motion. I think I read once that the optimal position of the limb bolts is cranked down almost all the way.... now I can see why as you would want the top retainer to be flush with the limb to distribute the load a bit more. For my lowish poundage, I don't think it matters much but for the higher poundages, it might stress the limbs a lot more.

I've never shot the bow with limbs cranked down and will see it doing that will at least engage the detent.


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## Jim C (Oct 15, 2002)

Its sad GT doesn't post here anymore-he'd put this to rest

I have shot WINEX 38 pound Long limbs on my Helix for two years now as my indoor set up. Still going strong and those were used limbs I got from RK. How the pivot point is gonna make a difference is beyond me when the limb set up is the same. in fact you get more stress on the limbs with say the older style handles based on what I have seen. Its more a draw length change.


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## Jim C (Oct 15, 2002)

omega_archer said:


> Hey Seattlepop,
> 
> What appears to be going on is something like this. The cross section is the limb.
> 
> ...


One of hoyt's top engineers george tekmitchov told me and others that the limbs work best NOT CRANKED DOWN. Earl Hoyt told me they work best in the mid to light position. Compound bows-I was always told to crank them down-thus if you wanted a 60 pound bow buy a 50-60, not a 55-65 or a 60-70./ But for recurves, I set them on the light setting based on what Earl and George told me.


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## omega_archer (Aug 25, 2008)

Jim C said:


> One of hoyt's top engineers george tekmitchov told me and others that the limbs work best NOT CRANKED DOWN. Earl Hoyt told me they work best in the mid to light position. Compound bows-I was always told to crank them down-thus if you wanted a 60 pound bow buy a 50-60, not a 55-65 or a 60-70./ But for recurves, I set them on the light setting based on what Earl and George told me.


Jim C, Interesting, maybe I heard that in my early compound days about the limb bolts. I'm not worried too much about the limb bolt position/setting, more the actual fit or lack thereof. I agree, it would be nice to here from some of the manufacturers here on AT.


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## Seattlepop (Dec 8, 2003)

omega_archer said:


> Hey Seattlepop,
> 
> What appears to be going on is something like this. The cross section is the limb.
> 
> ...


Much better drawing than mine! It does look like the detente can't seat because the "U" is stopping the limb from sliding in far enough. To test it I would remove the limb bolt altogether and then see if the limb will slide in far enough to seat in the proper detente hole. Then tilt the limb to see if it will lift up to where the limb-bolt cap would be.


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## omega_archer (Aug 25, 2008)

Unfortunately, the limb bolt is blocked by the riser bushing for a stabilizer mount so it doesn't just come out. When I slide the limb in without using the detent, I get the extra 0.030" - 0.040" thou so that the detent would hit the recess. I take it that your limbs sit in the riser detent OK.

Do you see any problem with elongating the slot?


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## Toxothise1440 (Nov 30, 2008)

Did you consider asking the manufacturer their advice? Before you take out the sandpaper, it might be a good idea.


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## Seattlepop (Dec 8, 2003)

omega_archer said:


> Unfortunately, the limb bolt is blocked by the riser bushing for a stabilizer mount so it doesn't just come out. When I slide the limb in without using the detent, I get the extra 0.030" - 0.040" thou so that the detent would hit the recess. I take it that your limbs sit in the riser detent OK.
> 
> Do you see any problem with elongating the slot?


If you can slide the limb in far enough to engage the detente (without the detente in the riser), then are we sure that the "U" slot is the problem? I have changed detentes on a pair of limbs and found that the angle of the detente bushing was different. If you look at the attached photo you can see that not all detente bushings are the same. Is it possible that the bushing is hanging up in the riser? Compare the two limb's bushings and see if they are different...

To answer your other questions, the bottom of the "U" can be made longer without damaging the limb - but let's be reasonable of course. As limbs move up and down with the limb bolt (as you crank the bolt in or out) the bottom of the "U" doesn't always touch the bolt anyway. The slot's primary purpose is to keep the limb from moving sideways so you definitely wouldn't want to widen it. 

And I have a set of Samick Universal 28#s that I put on a Matrix for training and rehab and had no problems.

View attachment 499589


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## omega_archer (Aug 25, 2008)

6cuda6;1053510699
I would suspect the best is to replace the riser with something more current......????[/QUOTE said:


> Might be a good excuse don't you think.
> 
> Seattle Pop, I measured what I could with the detents still on the riser. The diameters, heights are essentially identical so I would think the angles are pretty close.
> 
> ...


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## Dave T (Mar 24, 2004)

> With the limbs bolts down a full turn, things seem to be supported better and I can get the limbs out fairly easily by myself as well.


Not accusing you of anything, just wondering. Is there any posibility you backed the limb bolts out too far and that is causing all the problems? One of the first Hoyt's I had came with a manual that warned not to turn the bolts out too far as the limb would be unsupported, or words to that effect.

Dave


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## omega_archer (Aug 25, 2008)

Dave T said:


> Not accusing you of anything, just wondering. Is there any posibility you backed the limb bolts out too far and that is causing all the problems? One of the first Hoyt's I had came with a manual that warned not to turn the bolts out too far as the limb would be unsupported, or words to that effect.
> 
> Dave


No worries Dave, the old Radian has physical stop so you can't go past a certain the stabilizer bushing. See the photos. I'll read the manual again to see what it says.


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## Seattlepop (Dec 8, 2003)

Perhaps the distance here is not wide enough which would explain why cranked down, the limb fits better. On my Matrix, for comparison, I get 15mm. Also, look at the photo and compare to the Radian. Is the bottom "washer" wider than this? You can see how this could limit the angle at which a limb can be mounted if the bottom "washer" is too wide.



View attachment 499814

View attachment 499822


One last thought...check the spring in the detente. When you try to push the button in with your thumb, is it hard to push in? It should actually hurt your thumb to try to push the button in all the way. I had a pr of limbs that kept falling out of the limb pocket when I would string or unstring the bow. I took the spring out, stretched it and put it back in which fixed the problem.


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## omega_archer (Aug 25, 2008)

It is small like yours, maybe a little larger. I didn't draw my sketch to scale. The detent is working properly as well.

BTW.. thanks everyone, it's been helpful to me to go through this exercise and hopefully will benefit others.


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## BergerButton (Dec 3, 2008)

Obtain a rat tail file that fits the slot of that limb. Work the file with forward motion till you are able to elongate that slot by say 1/8". Keep doing this till it fits the riser. After you can coat the slot with some polyurethane. If the limb fits to tightly in the riser file or sand the area that is binding and then touch it up. Or get another riser?


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## Vittorio (Jul 17, 2003)

Considering that there is not a real standard for the so called ILF, each manufacturer tries:
1) to make for sure their limbs fitting their risers properly
2) to make their risers or/and their limbs fitting almost all of the existing limbs/risers
3) so, technically speacking, they just loose the tolerancies from 1) to reach 2).

Basically, users have to remember that limbs bolt are for minor poundage adjustment related to balancing (tiller) of the limbs, not primerly designed to change significantly the poundage of the bow, so possible practical excursion of the adjustemnt bolt is limited by definition.
Basic point in the proper fitting remains the need to have the end of the U in contact with the top inner flat part of the bolt. Without this, operation of the limb is going to stress the guide-bolt in the dovetail recess and makes full sistem unstable and subjected to breakages. So, ever make sure that following 2 limits are ever kept, for safety reason:
1) minimum of 5 or more threads of the limb bolt fully inside their female counterpart (all risers but Spigarelli and Bernardini, as they have their own safety system to make a limit on this)
2) ending part of the U in full contact with the inner top (flat) part of the bolt
How the dovetail and the corresponding limb insert are coupling is NOT important, nor is important if the elastic button in said insert is perfectly coupling with the semi-hole at the end of the dove tail (if existing). Centering of the limb is assured by it and the continuous slot in the center of the dovetail, only. 

So, there are phisical coupling limits betwen any riser/limb combination, and the first thing you have to do is to check them with the bow unstrung before doing any tuning adjustement. Going out of these limits means to have an unstable, noisy or even dangerous setup.


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## omega_archer (Aug 25, 2008)

Vittorio said:


> Considering that there is not a real standard for the so called ILF, each manufacturer tries:
> 1) to make for sure their limbs fitting their risers properly
> 2) to make their risers or/and their limbs fitting almost all of the existing limbs/risers
> 3) so, technically speacking, they just loose the tolerancies from 1) to reach 2).
> ...


Thanks Vittorio, that was very informative. I now believe I satisfy both 1 and 2. Before, the back end of the U did not contact the inner flat so I turned the bolt down until it did. Now I can pull the limb out and it actually has play in it so that I can actually hear the limb contact the the inner bolt face when unstrung.

The detent information will save me the time of trying to get it all fit perfectly.


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