PDA

View Full Version : Acu - trak cam rotation diagram in martin catalog



gibson 787
04-06-2011, 01:08 PM
Has anyone noticed the cam rotation position in the 'Single Cam String' diagram, on page 9of the new rytera / Martin catalog, It's definitely different from where most of us agree the optimum position is. I wonder?

As some of you know I recently converted my 09 Moab to a Firecat TR 1 and with the correct length string and cable, I ended up with ATA at 32 1/8" and BH at 7 1/4". Interestingly, the cam rotation was identical to the above mentioned diagram. It tuned easily and with my setup, was only 1 or 2 fps under IBO of 315fps. So I left the cam as it was.

My new Firecat 360 is a slightly different kettle of fish. When tuned, ATA is 32 1/4", BH 7 1/8" and IBO identical to Moab, but interestingly the cam position is more towards where most of us agree it should be, that is, in the catalog diagram the string comes off the cam at approx the hole next to the draw stop (my converted Moab), whereas on my Firecat 360, it's between the A and K of the ACU - Trak.

I guess at the end of the day, BH, ATA and cam rotation is subjective. If the bow tunes and shoots well, it's all good. :)

archerx7
04-06-2011, 01:21 PM
My 2011 catalog show a Shadowcat on page 9. Is this a hard copy or an online catalog ? If its online, can you post a link because the online catalog I pulled up is the same as my hard copy.

Just wondering what its showing because the FC 360 I have in the shop has the string coming off the cam right at the top of the A in the word "TRAK".

gibson 787
04-06-2011, 01:41 PM
My 2011 catalog show a Shadowcat on page 9. Is this a hard copy or an online catalog ? If its online, can you post a link because the online catalog I pulled up is the same as my hard copy.

Just wondering what its showing because the FC 360 I have in the shop has the string coming off the cam right at the top of the A in the word "TRAK".

Go to www.martinarchery.com then Tech info, bow Manuals, then 2010 Martin Compound Manual pdf. It's on page 9.

Hutch~n~Son Archery
04-06-2011, 01:48 PM
2372

Do you mean this?

Hutch:cool:

martinbowhunter
04-06-2011, 01:52 PM
2372

Do you mean this?

Hutch:cool:

That's exsactly how my cam timing looks on my firecat TR1.

gibson 787
04-06-2011, 01:53 PM
2372

Do you mean this?

Hutch:cool:

That's it Hutch.

Hutch~n~Son Archery
04-06-2011, 01:55 PM
In all the picks I have see on martin the string comes of the cam. If it is to be like the pic, that would advance the timing and retard the let off I would think?

Hutch:cool:

Hutch~n~Son Archery
04-06-2011, 01:59 PM
2373

This how I set up mine but according to the pic mine is too close.:confused:

Hutch:cool:

gibson 787
04-06-2011, 02:08 PM
In all the picks I have see on martin the string comes of the cam. If it is to be like the pic, that would advance the timing and retard the let off I would think?

Hutch:cool:

From all the info i have read, this is the only one Martin has indicated where the cam should be regarding their recent single cam models. Hutch, maybe we got it a bit wrong, or maybe it really doesn't matter too much, don't know??? But I do know the Moab shoots great with the cam well advanced and the FC 360 shoots great with the cam NOT advanced!

Hutch~n~Son Archery
04-06-2011, 02:18 PM
Strange part about it is, my strings are right at spec. and that is how the bow cam out. I even checked my ata and bh and the were fine.


Hutch:cool:

gibson 787
04-06-2011, 02:33 PM
Strange part about it is, my strings are right at spec. and that is how the bow cam out. I even checked my ata and bh and the were fine.


Hutch:cool:

Think I might phone Joel tomorrow and see what his view on the subject is.

Hutch~n~Son Archery
04-06-2011, 02:37 PM
Think I might phone Joel tomorrow and see what his view on the subject is.
Have some pics ready so you can email them. Most of the time that is what they will want. I am very curious what he will say.

Hutch:confused:

Hutch~n~Son Archery
04-06-2011, 02:51 PM
I just looked at my cam and if their diagram is right, it would make it so I would have to put the next draw mod in, other wise it would be to short of a dl. Their way would also make let off change quite a bit. I would like to know my self.

Hutch:cool:

gibson 787
04-06-2011, 03:13 PM
I just looked at my cam and if their diagram is right, it would make it so I would have to put the next draw mod in, other wise it would be to short of a dl. Their way would also make let off change quite a bit. I would like to know my self.

Hutch:cool:

It's a mystery how some bows are good to go and in spec with one cam configuration and others are not. I can understand it to a degree due to a situation where a rebuild has occurred as in my 09 Moab to a FC 360 probably because of slightly different riser shape.

Because of my time difference in Oz, i won't be phoning Joel until late in the afternoon (US time) and hopefully he'll be available.

RLW
04-07-2011, 07:48 AM
I was wondering early last year what the M2Pro timing was "suppose" to be at, and being anal about getting it perfect, so I called Martin (can't recall who i talked to)

What I was told that performance is same over a reasonably wide area and is it really isn't that critical of thier single cams.........mine is currently about have way between diagram and photo above, and fps is right where I would expect for my set-up down from claimed IBO ratings.

gibson 787
04-07-2011, 01:14 PM
I was wondering early last year what the M2Pro timing was "suppose" to be at, and being anal about getting it perfect, so I called Martin (can't recall who i talked to)

What I was told that performance is same over a reasonably wide area and is it really isn't that critical of thier single cams.........mine is currently about have way between diagram and photo above, and fps is right where I would expect for my set-up down from claimed IBO ratings.

Just tried to phone Joel, but he's currently on vacation until next tuesday. However, from what RLW was told, I'm now leaning fairly heavily towards what I suspected, in that cam position doesn't really matter, within reason of course. As long as ATA is within 1/2" and BH within 1/4" of specs and the bow is performing well, ie around 5 or 6 fps of the LOW IBO advertised speed, I wouldn't be concerned.

I'll contact Joel when he returns.

Hutch~n~Son Archery
04-07-2011, 02:24 PM
Still the cam being too far forward or too far back changes let off and dl. So this is puzzling.:confused:

Hutch:cool:

gibson 787
04-07-2011, 02:43 PM
Still the cam being too far forward or too far back changes let off and dl. So this is puzzling.:confused:

Hutch:cool:

I agree Hutch that DL and let off will alter, but fortunately we have mods and draw stop to play with as well as twisting and untwisting string/cable.

I personally think it's good that we can twist /untwist etc without having to worry about where the cam ends up. Just my opinion however.

Speedykills
04-07-2011, 06:10 PM
2373

This how I set up mine but according to the pic mine is too close.:confused:

Hutch:cool:

Mine looks like this, no problems at all.......................

archerx7
04-07-2011, 06:39 PM
I was wondering early last year what the M2Pro timing was "suppose" to be at, and being anal about getting it perfect, so I called Martin (can't recall who i talked to)

What I was told that performance is same over a reasonably wide area and is it really isn't that critical of thier single cams.........mine is currently about have way between diagram and photo above, and fps is right where I would expect for my set-up down from claimed IBO ratings.

When I spoke to Martins designer last year at the ATA show this was one of the questions I asked, his response is what was stated above by RLW. They design the single cams to have a certain degree of forgiveness to them as far as rotation is concerned so that the same cam can be used on all the different models. The rotation of the cam has very little to do with the letoff. The letoff is managed primarily by the modules on single cams and module equiped dual cams. Cam rotation will effect letoff on most all draw length specific single and dual cams however.

gibson 787
04-07-2011, 06:43 PM
When I spoke to Martins designer last year at the ATA show this was one of the questions I asked, his response is what was stated above by RLW. They design the single cams to have a certain degree of forgiveness to them as far as rotation is concerned so that the same cam can be used on all the different models. The rotation of the cam has very little to do with the letoff. The letoff is managed primarily by the modules on single cams and module equiped dual cams. Cam rotation will effect letoff on most all draw specific single and dual cams however.

Yeah Archer, I think you're spot on the money.