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Discussion Starter · #1 · (Edited)
For those who may be interested I have revised the much posted PP slide of the cam & 1/2 draw stop timing. I hope this addition will be easier to understand...
 

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Discussion Starter · #2 ·
To make it easier to follow I am

posting the other information in the thread as well... Hope this helps...

Hybrid Cam Sync & Timing
By Mike Javi.... Cooper​



The timing system on the hybrid cams is somewhat different from other systems.

The cams need to be in synchronization and in draw stop timing; these are two entirely different issues but interconnected. It is possible to have the cams in sync, but not in time and visa versa.

The string is for all practical purposes, just along for the ride, the buss cable (yoke) controls the bow, and it is used to set the axle to axle (limb) preload and takes most of the weight of the limb deflection at full draw. The control cable (slave) ties the two cams together so that they rotate at the required speeds.

The reference marks or holes (depending on the cam) are there to provide a visual reference to cam synchronization not draw stop timing. I find that tiller is a more precise indicator of cam sync; if the limbs are bottomed out the tiller will reflect the position of the cams better than the reference holes (marks).

To adjust the cams, I back the string off until I’m sure it isn’t affecting the axle to axle (usually ten twists will do) then adjust the buss cable to bring the axle to axle measurement to a ¼” longer than the specifications for that particular cam/limb combination (see Hoyt tune charts). The control cable should be used to sync the rotation of the cams while doing this. If the cams are in sync at this point the reference holes will be equidistance from their respective cables and the tiller will be even (limbs bottomed out).

Now is the time to adjust the draw stop timing, using a draw board or similar device (you can draw the bow and have someone else look at the cams) when the bottom cam’s draw stop is just touching the buss cable, the control cable should lay flat in the groove of the top cam. If the cam is under rotated you can put a twist in the buss or untwist the control, I determine which I do by the draw weight and draw length of the bow. Shortening the buss cable will lengthen the draw and increase the draw weight. Shortening the control cable will decrease the draw length and decrease the draw weight.

At this point, I measure the draw length (using AMO standards); it should be long and the draw weight should be higher than spec for the bow. I will then twist the string to bring the draw length to spec; this should also bring the draw weight and axle to axle into spec.

I double check everything and tweak a half twist here or there to fine tune it.

Finally I use the hybrid cam creep tuning method to set the bow to my shooting style.

If you follow this method you will have a very solid wall and the bow will be practically vibration free.

A note: the regular cam & ½ should be tuned in the “D” draw length slot for best performance. You can then set the module to your required DL and tweak the DL using the string.
 

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Great post!!!!!!!!! :beer:
 

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As usual, nice work Javi!!
 

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Hey, Javi, thanks. You're a real life saver. You must be real popular with the rest of the Hoyt/Reflex guys, huh? Thanks again, because I have noone nearby who could time my Slam.5. It is now timed and synced.
 

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stupid but maybe there are others

I have to get a new string after season and have one question -

You state that it should be tuned in the D slot yet all the Hoyt chart measurements are for C slot.

So, before I back off the string to measure AtoA +1/4, do I set it in the C slot or the D slot?

Thanks.
 

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Discussion Starter · #7 ·
yelk hunter said:
I have to get a new string after season and have one question -

You state that it should be tuned in the D slot yet all the Hoyt chart measurements are for C slot.

So, before I back off the string to measure AtoA +1/4, do I set it in the C slot or the D slot?

Thanks.
If the Hoyt chart says "C" then use "C", however I find most use "D" instead...
 

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I see what you mean! I just looked at their charts again to make sure - I have the Xtec and it is all "C" for 2004. Again, thanks.
 

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Javi, any idea what draw length setting I should be on for the Slam and a Half? I did it set at 30, the longest setting. It seemed sensible.
 

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Discussion Starter · #12 ·
Creep or fine tuning the Hoyt Cam & ½
By Mike (Javi..) Cooper

It is a variation on the old stand by Creep tuning methods…
With the tiller set to even (limb bolts bottomed and backed out the same on both limbs to your shooting weight) Set the timing as close as you can by eye.
I like to start with my sight zeroed at 20 yards.
Using ½ or ¾ inch masking put a horizontal line on your 20 yard target.
Shoot 3 or 4 arrows aiming at the tape, be sure to draw only to the wall do not pull into the limbs. Only use your good shots; the bad ones don’t count.
This is where the Cam & ½ differs from the two cam bow in creep tuning. Since there is no real valley you can’t creep into it.
Now shoot 3 or 4 more arrows at the line, while drawing your bow hard into the cams (you’re over rotating the cams just a bit) this is what most people describe as the mushy felling on the cam & 1/2. Again use only your good shots.
If your bow is in perfect time all your shots will hit the line, and the mushy feeling will be almost unnoticeable. If the shots fired while pulling hard into the cams hit high, apply a ½ twist to the control cable.
If the shots fired while pulling hard into the cams hit low apply a ½ twist to the buss cable.

Repeat until all shots hit the tape….

If you want to tune it even closer; repeat at 30 or 40 yards….
 

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Javi,

Got a question for you that I don't understand

A note: the regular cam & ½ should be tuned in the “D” draw length slot for best performance. You can then set the module to your required DL and tweak the DL using the string
How can you set the modules to the required DL? I thought that by changing the slot (ABCDEF) that this was what controlled your DL. So what are you talking about in that last sentence?
 

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Discussion Starter · #14 ·
shoff14 said:
Javi,

Got a question for you that I don't understand



How can you set the modules to the required DL? I thought that by changing the slot (ABCDEF) that this was what controlled your DL. So what are you talking about in that last sentence?
The measurments for the Hoyt regular cam 1/2 i.e draw weight, axle to axle, and brace height are taken in either "C" or "D" slot... while the change isn't significant there are differences so I recommend that you "use" the slot as deginated by Hoyt (example: http://www.hoyt.com/technical/charts.tpl?page=04_ultratec.inc 2004 UltraTec w/XT2000 limbs is spec'ed to be in "D" slot of the module). Once you have the bow set to all specs and the cams in time and sync, then you change the module to the corrct draw length for you...
 

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so your saying you don't have to shoot the bow in those positions, but you need to set them up and get them in spec in those positions and then work from there? So it doesn't matter what module position you shoot in, just when you set it up and time it. Is this a correct asumption?
 

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ttt

we should all read this one from time to time......an absolutely awesome post by Javi. Perhaps this is the best single post ever on AT.

J
 

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cam timing

Javi, when I got my new trophy bound string for my protec, I put it on and set it up via your directions above. Worked perfect. On to my excursion. If I get the timing marks set right with the control cable, when I check the draw stop, the top cam is under rotated. When I twist the buss cable to get the cam rotated, it throws the timing marks off again. If I go and retime the control cable, it throws the draw stop timing off again. Arghh, what am I doing wrong? Tiller is perfect. The bow shoots perfect bullet holes at 10 feet. I can't go outside and shoot as we have a little problem with snow here in Wisconsin right now and the targets are all froze up. Do those timing marks mean anything? I should add, I have the original floating yoke cables and string on the bow.
 

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I'm no Javi, for sure, but with my XP35 with the Slam.5 cams I had to go more by brace height and ata measurements. I'm prety sure you don't have to be dead center in the holes (timing marks). I creep tuned afterward and it's shooting better than ever. Mine is not dead center over the holes, but equidistant.

If I'm wrong, Javi, please fill me in. Oh, and tell me why if you could. I'm sort of a brain-picker. :teeth:
 
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