# Cam & idler lean on single cam bow



## Jathinkysaurus (Oct 8, 2006)

I would like to clarify what I should be trying to acheive when setting idler lean. On my 2004 PSE Primos STL, the string groove on the cam is not in the centre of the limb; the cam has 3 grooves- the bus cable groove is in the centre, and the 2 ends of the string run in the outside grooves, so the arrow side of the string is about 1/4" off to the left of centre at the cam end. The idler wheel is dead centre of the top limb. This means that the string does not run parrallel to the centre of the riser.
So, when I lay an arrow shaft on the side of my idler wheel, should it be parrallel to the string, or should it be parrallel to the centre line of the limbs? 
Also, is there any way to adjust the lean of the cam itself? It is leaning out the opposite way from the string. Obviously, there is no yoke to adjust on that end.


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## red44 (Apr 11, 2005)

I would like to see input from others as well. To start with I'd set it so an arrow placed along the idler will run parallel with the string. At full draw peek up and see how the string is coming off the idler. Is it centered or coming off more to one side? Noted. From here I would shoot bare shafts. I'd adjust the rest slightly if needed to get them flying straight, no left right/tail. If I could not get it with the rest, then put a few twists in the yoke on the side of the tail. Go back to the rest and see if you can get it flying correct. If this yoke adjustment made it worse, untwist what you put in and twist the other side. On a Mathews, I seen it advised not to exceed 1/16 of an inch difference on ATA side to side, and that you want it straight at full draw. You also should not have to make excesive rest movements. If your way in or out something is up. Now I haven't seen and done it all so someone else please advise.


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## Jathinkysaurus (Oct 8, 2006)

When i look up at full draw, the string is definitely coming off the left of the idler, same as at brace. I won't have time now to tinker, or to get on AT, for the next few days as I'm about to start some night shifts. I'd be grateful for any further advice on this but won't be able to respond until next week.


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## red44 (Apr 11, 2005)

As I remember you had broadheads hitting left of fieldpoints. I would'nt be afraid to get the idler straight at brace and see what difference it makes on the broadhead/fieldpoint impact. Keep track of any twist so as to be able to get back to your starting point. Anyone else?


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## red44 (Apr 11, 2005)

Anybody else have a plan of attack?


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## NMP (Aug 6, 2003)

I allways set the idler on the PSE bows that I have had straight with the centerline of the bow at brace. This has allways worked great for me.


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## Deezlin (Feb 5, 2004)

I don't know too much about PSEs. I would get the idler parrellel with the string.


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## archer58 in pa (Jan 3, 2007)

red44 said:


> I would like to see input from others as well. To start with I'd set it so an arrow placed along the idler will run parallel with the string. At full draw peek up and see how the string is coming off the idler. Is it centered or coming off more to one side? Noted.



The arrow running parallel is the best(as far as simple) method I have used.
Eye balling the top idler is tough on cam & 1/2 hoyts. Wheels are easier to see the vertical orientation. The string may appear to come off the side because the bottom cam is usually NOT in the middle of the limbs. None the less, this is a great start and as you stated bare shafting will show if you're close to vertical. A twist or two from there is all that's needed from there.


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## GRIM (Mar 8, 2006)

yoke tune it, twist the arrow side to reduce ATA on that side no more than 1/16, then paper tune to a bullet. The idler should sit straight at full draw and not static position. I have been doing it this way for years and there are quite a few articles out there that explain this method. Do this and fp and bh will hit the same.


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## Corsair (Nov 21, 2005)

I tried checking my Prestige for idler lean last night and sure enough at full draw the damn thing leans to the left. At rest it is perfect.

I note what was said above regarding what Mathews say but I'm really puzzled. If you get it perfect at full draw, won't it be on a lean at rest?
This means that the string will be moving from a perfect idler set up to a leaning one as the shot progresses. 

Why isn't it better to start with the lean at full draw and have the string progress to a perfect idler orientation at rest???

Bloody compound bows confuse me more and more every day:sad:


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## red44 (Apr 11, 2005)

http://forums.mathewsinc.com/viewtopic.php?t=43031 If I'm reading right he is now trying to split the difference. But my first comment/question would be how is it shooting?


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## Deezlin (Feb 5, 2004)

Corsair said:


> Why isn't it better to start with the lean at full draw and have the string progress to a perfect idler orientation at rest???


The cam lean will affect the launch of the arrow some. I like to get the lean adjusted by bare shaft tuning so the nock is approximately straight. I set the idler wheel lean parallel.

I then eye ball the center shot, shoot in at 20 yards and do a walk back. Not real far. I then do a bare shaft tuning and adjust the lean depending on nock left or right. Once I have the best cam lean condition, I do a final walk back.

The lack of cam lean is really not very important to accuracy, but it helps some to get the best launch. If it gets too sever you will have excessive cable and string wear and the possibility of derailment. The bearing life and axle pockets wear will also be shortened some too.


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## Corsair (Nov 21, 2005)

Hi Deezlin



> I then eye ball the center shot, shoot in at 20 yards and do a walk back. Not real far. I then do a bare shaft tuning and adjust the lean depending on nock left or right. Once I have the best cam lean condition, I do a final walk back.


That's interesting. I would never have thought of doing this but what you say makes a lot of sense. Thanks for that. I'll give it a go.


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