[300 Mag]

I have a Hoyt Ultra-Tec (spiral cams) that I have tuned according to Javi - I spent hours on this thing and its is DEAD on with all specs and cam timing and synch, but my tiller is about 1/8" off on bottom limb.

Here's my thoughts - right or wrong but here we go!!!

Javi has written many many times that if your cams are in synch that your tiller should be even BUT...........

#1 - what about machining tolerances - risers and limb pockets??

#2 - what about the cams themselves - tolerances, machining etc....???

#3- What about limb tolerances -(thickness etc...)??

#4 - Limb bolt tolerances - bolts themselves and washers on limb bolts??

I am not starting any controversy, but it seems to me that there has to be a more accurate way to check cam synch?? I don't think tiller measurements are precise enough to truly measure cam synch. I have Hoyt bows that shot well with slightly different tiller measurements. Tiller is more of a personal feel when the bow is drawn.

(I synch my cams by feel and by walk back tuning.)


Javi is the man when it comes to super tuning Hoyt cams!!

Do you guys (especially Javi and Nuts & Bolts) agree that some of these machining intolerances could actually bias tiller measurements a little??

I'm looking for some other thoughts and suggestions - by no means at all am I going against the grain here - just picking your brains a little. Maybe its just my obesssive compulsive disorder??

 

[300 Mag]

ttt

 

[JAVI]

Here is what you are actually measuring….

There is a small area on the cams that is equal distance to the axles on both the upper and lower cams… this area is approximately 3/8” to ½” long, ( right where the string comes off the cams at rest if properly rotated) depending on the diameter of the cams… What you are measuring is the fact that you are within that area on both cams; nothing more… This assures that the cams will begin to rotate at the same time, and travel the correct distance as the nock point is not in the center of the string and the cams are not equal distance around. If one cam is out of sync, even though it hits the draw stop at the same time it will cause the bow to be unbalanced.

Yes there can be a stacking of tolerances in the manufacturing process, but that would be of little consequence to this process except to alter the reference dimensions of axle to axle and brace; which are nothing more than a guide to the preload on the limbs. Measurement of the draw weight and draw length will be more precise for indicating preload anyway.

If your tiller is off an 1/8” it simply means that you have not quite hit the sweet spot with the control cable, which will move the top cam in one direction of rotation and the bottom cam in the opposite direction albeit at different rates of movement. It is sometimes necessary to use a ½ twist in one cable while taking a ½ or even one full twist out of the other to balance the cams so that they are in synchronization and the draw stops hit at the same time…

I hope this clarifies the process a little bit.

 

[300 Mag]

Thanks Javi!!

Again - great technical information!! Very precise and detailed.

You are the man with the hoyt cam system!!! :wink: