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View Full Version : Can someone explain how moving draw stop messes up cam synchronization



rdhj
03-01-2013, 12:35 PM
been messing with my onza trying to find the perfect draw length and let of combo...after moving the module to a half inch longer and then moving the draw stop to get it back to where it was with less let off, the am sync was off....so I adjusted the cables and got it sync...was at the range today and moved the stop a little and the arrows were hitting way off....pull it down on a bow hanger to only find the sync was out....i thought since the cams were slaved to each other that if the bottom cam was changed due to the draw stop, the top one would also adjust itself and maintain the sync...what gives???

wscywabbit
03-01-2013, 01:19 PM
You are correct, the cams are slaved and the draw stop doesn't affect the sync. I'm not sure how you're getting problems out of moving the stop... :confused:

rdhj
03-01-2013, 01:54 PM
great...something must be screwed upchecked one of the cables and the string for length and they were right on the money....attempting to fix it bu placing it on the draw board...drawing it to 28.5"....placed the draw stop at the limb and marked it...now i'm subtracting twists from each cable to try top retard each cam, but after 7 untwists , it doesnt seem to be getting any closer to the cam stops...any ideas?

Mike G
03-01-2013, 02:26 PM
I'm not sure if this will explain it, but I think I know what is going on.

The draw stop is only on the bottom cam.

When you draw back your bow, the bottom cam stops but the top cam will keep advancing to the bottom of the valley. Lengthen the draw lenght about .5".

Watch the cams closely and draw very slowly, mark your cams in 1/4" increments with a pencil and as you draw the bow watch as to where and when they go out of sync. I think you will see they are synced up until the very end.

I can't see any other way that just moving the draw stop alone could make a difference in cam sync.

You may need to resync the cams now because of the adjustments you already made to them. Sync up the cams without a draw stop in place at all. You really do not need a draw stop, just find a good solid anchor point first. Then set the draw stop to match your anchor point.

rdhj
03-01-2013, 02:46 PM
Mike...the cams are not out of sync really...they just are not coming to the draw stops when use the draw stop to stop the rotation at 28.8 with the module set on 28.5.....almost like the 28.5" module setting is really 29"

droppixel
03-01-2013, 03:49 PM
You sure you have them mods on the correct number for the draw you are looking for?

wscywabbit
03-01-2013, 04:09 PM
don't get caught up on which number the draw length modules are set at, just set them so that a comination of draw stop and module setting feels comfortable to you and isn't over-rotating past the flat cable stops....

The draw length can be effected by any comination of this, as well as the length of the cables (slightly) and the length of the shoot string (moderately).

rdhj
03-01-2013, 04:12 PM
the modules go from 27.5 to 30.5 in half inch increments an I have it on #3..so it should be 28.5"

rdhj
03-01-2013, 06:52 PM
well, put the 7 twists back in both cables and they were close...top cam was a little advanced...fixed that with 2.5 added twists....then changed the module to the #2 hole and ended up with 28 3/4" DL, which might work for me.....ATA ends up being 33.5" so its 1/4" over....should i worry about that since the limbs are not maxed out and is this close enough?

wscywabbit
03-01-2013, 07:11 PM
depends on how far out they are. Typically you want to measure ATA and Brace when the bow is fully maxed out to be in spec, as you back out the limb bolts a lot of things change. So your ATA being a little off is not that big a deal. Although usually when you let out the bolts your ATA goes down not up, and your draw length gets longer...

Sonny Thomas
03-01-2013, 09:37 PM
You have run into one of the things I hate about bow "tricks." My side of the story; I run the shop and at the shop no one discusses "tricks" with my customers in my presence. I'll order them out of the place. Customer wants to go "trick" his bow, fine, but not at the shop. I'm that serious. Running a shop you have a liability responsibility.

You want the perfect draw length? Then set your bow by the Martin manual, mods to desired draw length (that fits, not by the numbers), cams synced, draw stop set.
I take it that you are using a loop. This is fine just make loops of 3 or 4 different lengths, 1/4" difference to start. These can be shortened by melting the ends back. Try each loop length until overall draw length is best for you. Do not use a loop so short that it creates crush, squeezes the center serving or creates nock pinch. If a tad bit long, then play with the draw stop - this being advancing the draw stop. Don't move or change anything except the draw stop. Advancing the draw stop does four things, it shortens the bow's (1)draw length, (2)shortens the valley, (3) lessens letoff and (4) has the cables not lay entirely flat in the module groove flats. Your bow is still timed, synced and all, just that the draw stop is changing cam locations. Okay, it's no different than if you have the draw stop set short. Here, the cams will rotate so the modules will push the cables, both at the same time, before the draw stop hits, but the bow is still timed, synced and all.

pizzadave
03-02-2013, 06:46 AM
I know for a fact that you can't trust the number of the mods. My alien nemesis is set up on the 3rd from last spot, which I believe is probably a #5 and should be 29" on the Hybrix 2.0 cam. My draw stop is back just a hair so that the cables lay flat on the mods. It was this way out of box, and this fits me perfect. Low and behold, this is about 29 1/2'' according to my checking, but 30" according to the local shop. I am guessing my bow draws a solid 1/2 - 3/4'' long.

I guess what I am saying is follow Sonny's orders, and it will work great. Those little "tricks" can definitely hurt more than hinder, especially when you go overboard. I had a guy that supposedly knew bows help me with my 2010 Cheetah, and he had so many twists in my "y" cable to get the top straight that it actually over bent the top limb, and made it shoot all out of whack. Tricks are ok, but used in moderation.

rdhj
03-03-2013, 07:09 AM
thanks for all the help...i think I have it set right now...basically did what Sonny said, but havent tried different length loops yet...ordered 10 feet of material off ebay last night some later this week I will experiment if I feel it need to be different after shooting league tomorrow night

rdhj
03-03-2013, 08:03 AM
now that everything is set up right, my peep sight is off....is there a way I can twist the string to move the peep without affecting the draw length i just set my taking a twist out of each end?

Sonny Thomas
03-03-2013, 01:52 PM
You didn't say how far off and if the loop is staying straight back. Loop is always to stay straight back. You can a few things without effecting draw length. First, always twist from the bottom cam. This gives a finer tune of the peep. Next, if way off, better that 90 degrees, switch peep around in the string. Use half twists and check peep for location. Again, keep loop straight back. Fire some where around 5 to 8 shots to settle string and see where peep ends up. I'd go as much and 1 1/2 twist in one direction. If peep isn't behaving remove the 1 1/2 twists and start twists in opposite direction. Stubborn sometimes, loop straight back, hold loop and twist the living daylights out of the peep. The shoot 3 to 5 shots to see if peep behaves. Why twist the peep so aggressively is to get under the serving a bit.

Again, loop straight back, twist string from bottom cam and adjust in half twists of the bow string.

Don't be overly perfect. What you want is the peep to be straight when at full draw. If the peep is off a bit with bow relaxed no big deal.