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bwhntr7973
04-04-2012, 06:47 PM
I just got my 2009 Firecat back from my local bow shop and it is shooting good but I am wondering about the timing of the cams. I had Joel from Martin sending some new cams because the others were tweaked pretty good and one of my local shops put them on for me. My only question is if they timed the cams correctly. I can't seem to be able to find any timing marks other than going by the number 5 hole for the draw length mods. Before they were changed I was getting 280 fps with a 415 grain arrow and now I am only getting 269-270 fps with a 407 grain arrow. I have attached some pics so you can see what I am talking about with the timing.

Anything will help!

wscywabbit
04-04-2012, 07:54 PM
Check this link out it has some good info andshows one of the easiest ways to time these cams:

http://martinarchery.com/mtechforum/showthread.php?23567-Nemesis-Alien-Set-ups

CarlosII
04-05-2012, 04:16 AM
is it in spec? ata, bh?

bfisher
04-05-2012, 05:06 AM
That video shows a very good way to check the cam timing at nearly full draw. The cables should come to the pencil mark at the same time. Something else I always do is, once the cam timing is set and the draw length tweaked to where I want it is to draw a line on the side of the cam edge where it passes through the limb fork. Doing this gives me a visual reference so if the cables would stretch unevenly or I'd change the rigging I can just look at those marks to get the bow back to where I originally had it set.

There are no timing mrks on the cams as they can be set to where ever you desire for a certain feel or performance. I usually advance my cams (counter clockwise in the left hand pic) by twisting the string to give a smoother draw. This removes some of the hump right before the cams roll over. It gives up some speed, which I don't care about anyway, but makes the bow feel better to me. This also shortens the draw length which can be reset using the module and draw stop.

Although you're not using pencil marks on the module to check cam timing it appears that they are pretty close by using the #5 hole in relation to the cable. There can very several reasons why you lost about 10 fps with the new cams. What many people don't do is measure and/or mark the cams and write down the specs as they originally were. Big mistake. Is the bow set to the exat same specs as before? It could very well be that the cams are not wrapped up quite as tight as the originals. Maybe the string/cables are not set to the same length as before. Is this the same rigging? Was anything added to the string? With the mods set in the #5 hole it should be at 29" draw, but have you actually measured it on a draw board? Is the draw weight the same?

Different lighting can make a difference in what the chrono reads. Still, assuming a 29" draw and computing from the IBO rating I would think your speed right now is on the slow side. The 8 grains difference in arrows only amounts to 2'/sec so that's not much of an issue. What I often find is that IBO ratings are inflated by about 20'/sec on most bows, Martin being no different. Still, you're not worrying so much about this as the amount of change from before. Maybe do some tweaking, add a few twists to the cables to get better efficiency from the cams.

Using a post on AT about optimizing the Cat cams (same as you'rs) you could twist the cables more so that the cables run right through the middle of that #5 hole. This will make the draw length a bit longer, but this can be compensated with the draw mod and draw stop. There's a good explanation on at about this. Do a search for "Optimizing Cat Cams".

droppixel
04-05-2012, 05:16 AM
That video shows a very good way to check the cam timing at nearly full draw. The cables should come to the pencil mark at the same time. Something else I always do is, once the cam timing is set and the draw length tweaked to where I want it is to draw a line on the side of the cam edge where it passes through the limb fork. Doing this gives me a visual reference so if the cables would stretch unevenly or I'd change the rigging I can just look at those marks to get the bow back to where I originally had it set.

Didn't think about doing that! Totally going to have to mark mine.

Spiker
04-05-2012, 06:04 AM
What Barry said.!
#1 The timing needs to be done at full draw, not at rest. Watch Jims video again on how to set them.
From your pics - the cams need to be wrapped up tighter. Measure from the cable post to the cable - this should be right on 1/8" at rest.
Here is a link to the AT thread about setting the cams: http://www.archerytalk.com/vb/showthread.php?t=626601

From the pics - if it were mine - I would add 3 twists to each cable and take 1 twist out of the string. Then check all the measurements.
Then - at full draw - check to see if the cams are in time with each other. Make a slight adjustment if they are not perfect, then check your
speed again.

bwhntr7973
04-05-2012, 06:20 PM
Yeah, there is a lot of good info on here from all you guys. I measured from the cable post to the cable and the top cam measurement is right about 3/16 so about 1/16 to more than the 1/8" and the bottom cam is right about 5/32 so about 1/32 more than the 1/8".

I checked my ATA and it is 32.5" center of limb (where the cam pin is) to the other center of limb. I also measured my brace height from the deepest part of the grip to the string and it is sitting right at 7".

To reply to bfisher, I am not sure if everything was set back to the same specs as before due to having the cams put on by my local bow shop. I am hoping they did measurements but I am just not certain about whether they did or not. I know that when I received it back from Martin with the new cams and limbs the cable post was right at 1/8" both top and bottom. Seemed to be a bit smoother and shoot faster at that setting.

The other question is, is how easy is changing the cam timing by yourself. I don't have a bow press and have never done this yet but could most likely figure it out easy enough if given the proper guidance. I have seen where you can draw the string back enough to get a steal dowel or screwdriver through the cams to make a bow press in a pinch. I just do not want to damage the cams or anything else in doing this.

The other question is how far would I need to twist my cables and in what direction.

bfisher
04-06-2012, 05:42 AM
Don't use a dowel or screwdriver in the cams. Martin bows are pretty unique within the archery industry. One of the few brands that you can back out the limb bolts enough to relieve tension on the rigging. You can do this yourself. Just back out the limb bolts evenly (same amount of turns per limb). If the bolts are bottomed now then it's usually about 12 turns or until you see daylight through the barrel nuts the bolt screw into, as viewed from the side. When you can see about half a hole through the barrel nut there should be slack, or nearly so, on the rigging. At this point you can just slip the string off the cam like a bicycle chain and work on the bow. Putting it back together is just the reverse order. Just remember to record whatever you do so you can change it back if need be and take some digital photos of the cable routing on the cams in the event you forget. After you're done you'll probably have to shorten the module by one hole and reset the draw stop accordingly. Then check and/or retune the bow.

bwhntr7973
04-06-2012, 10:08 AM
Thanks Barry! Good info as usual. I did not know that about the Martin bows and relaxing the string. If I were to put a twist or two in the cable strings, which way would make it to where it would bring the cable post closer to the 1/8" away from the cable itself? Do I just look at what way the cable is twisted currently and add another twist to it?

I love these forum sights becuase of all the information I get out of them!

droppixel
04-06-2012, 11:04 AM
Thanks Barry! Good info as usual. I did not know that about the Martin bows and relaxing the string. If I were to put a twist or two in the cable strings, which way would make it to where it would bring the cable post closer to the 1/8" away from the cable itself? Do I just look at what way the cable is twisted currently and add another twist to it?

I love these forum sights becuase of all the information I get out of them!

I wouldn't worry about the distance from the post as much as the cables contacting the mods at exactly the same time at the same point on each mod respectively. I would look it up to double check me or wait for another post, but I think you put twists into the cable connected to the cam that is advanced.

Spiker
04-06-2012, 11:08 AM
Yes - back the limb bolts out till the rigging is loose then take the cable off the outer post of the cam and add 2 twists tighter to it.
Do the same to the other cable on the other cam.
Then tighten your limb bolts all the way back in and see what the measurement is from the post to the cable.
If it is at 1/8" - then measure your axle to axle and see if it is still in spec.
If ata is short - back the limb bolts out again and take one twist out of the shooting string.
Tighten it up and check again.

After you add the initial twists to the cables and tighten it back up - you will be able to see the amount of change it made and will
know what to do to get it where you want it.

Spiker
04-06-2012, 11:12 AM
After getting the cams wrapped up and the ata on spec - then you will want to make sure they are timed together (at full draw)
like shown in the video posted earlier.
To adjust that you just add a half to one twist to one cable, or take a half or full out of the other cable will you get both modules
hitting at the same time.

bwhntr7973
04-08-2012, 05:08 PM
Yes - back the limb bolts out till the rigging is loose then take the cable off the outer post of the cam and add 2 twists tighter to it.
Do the same to the other cable on the other cam.
Then tighten your limb bolts all the way back in and see what the measurement is from the post to the cable.
If it is at 1/8" - then measure your axle to axle and see if it is still in spec.
If ata is short - back the limb bolts out again and take one twist out of the shooting string.
Tighten it up and check again.

After you add the initial twists to the cables and tighten it back up - you will be able to see the amount of change it made and will
know what to do to get it where you want it.
When you are referring to the outer post of the cams are you referring to the cam post that is outside (or above the limb) of the limb vs. the cable post that is on the interior of the limb?
Everything else is clear, but I am not quite understanding the outer post!
Thanks, great info!

droppixel
04-08-2012, 06:43 PM
When you are referring to the outer post of the cams are you referring to the cam post that is outside (or above the limb) of the limb vs. the cable post that is on the interior of the limb?
Everything else is clear, but I am not quite understanding the outer post!
Thanks, great info!

6227

There you go ;)

bfisher
04-08-2012, 08:58 PM
6227

There you go ;)

Which proves again just how useful pictures can be. Good job.

bwhntr7973
04-09-2012, 12:07 AM
Awesome! That is the post I thought you were talking about but wasn't positive. That definitely helps out!

droppixel
04-09-2012, 09:33 AM
Awesome! That is the post I thought you were talking about but wasn't positive. That definitely helps out!

What we're all here for ;) Learned a ton over the past year from all the guys here and that has helped me pay it forward.

boothill
04-15-2012, 09:07 PM
So if I put my bow in the press and add a couple of twists to the power cables it will bring the post closer to the cable? I just put new cables and string on my Onza and the posts are approx 1/4" from post to cable right now. They are even on both sides but still a wider gap than 1/8" that is needed. Man I love this tech forum for this type of information.

Much Thanks

wscywabbit
04-16-2012, 11:35 AM
adding twists to the cables will move the posts closer to the limbs, so "optimal" would be about 1/8" gap between the post and the limb. However, that is just one visual cue to watch. You should still make sure that the cams are timed correctly and that your draw weight, ATA and Brace are in spec... remember, adding twists to your cables will raise your draw weight, shorten your ATA, and lengthen your Brace.So pay attention to them and try to keep them in line with spec.

boothill
04-16-2012, 09:13 PM
So I did a little tuning on the Onza today. I put twists in the power cables and they now have just over 1/8" gap. The poundage I thought I'd lost when new strings and cables were installed is back. As well as the ATA and brace height being correct. The bow draws smoother and is much quieter than before. Thanks for all the help guys.

wscywabbit
04-16-2012, 10:45 PM
glad to hear you got it worked out! We're all here to help one another, so no worries. Hang around and you'll learn lots from these guys, I know I have! ;)