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View Full Version : Martin Cheetah and bowstring update for bfisher



Bowhunter_IL_BT
06-04-2010, 07:09 PM
Hey bfisher we talked about a month ago. I finally got my H&M bowsting on today. The string went on smoothly, but my buddy had to make some adjustments when he compared the axle to axle length and tried to make sure the length was as close to specs as possible. I put a G5 Metapeep on the bow and it shoots nice and is quieter. My buddy told me to shoot around 30 shots to break the string in a little. With the Metapeep he recommended to shoot it about 200 times before tieing in the metapeep.

My buddy at the local cabelas used an easton clip on bow scale and he had my cheetah at 76 lbs. I was in shock :eek: cause it did not feel any heavier than before. Im looking to get a second measurement somewhere else. Does the new string make the poundage go up? I had it around 72 lbs. before I put the new string on. Plus my speed was 246 fps before. Now today my speed was 262 fps. I forgot to mention that I increased my draw one inch (26 in.) and took off the tube peep for the metapeep. The scary thing is if its 76 lbs. I may have to get new arrows cause IBO min be 380 grains. My arrows are 360 grains now and with a tracer nock 373 grains. I shot about 50 arrows today and it seemed ok but I need to double check that poundage.

alex
06-05-2010, 02:40 AM
You'd better lower the poundage or soon the limbs may "die". I guess the going-as-closer-to-the-specs is the reason for the heavier DW. I think it's better the bow to feel and shoot good in your hands instead of following the specs exactly. :)

Montalaar
06-05-2010, 05:17 AM
At first i would try to find some more people to measure your draw weight. Inofficial studies here brought the result that there can be a difference of up to 10 lbs with different scales. Even with one scale there can be a great variability depending on the way the scale is drawn on the bow.

Have you measured your ATA7BH before changing to the new strings? If yes: try to get your specs close to the old ones.

As Barry would say:
See the specs from martin as a vague guidance and not as a must have.

bfisher
06-05-2010, 12:47 PM
Most of your questions have alerady been answered so I won't go into great detail. I would also say to get the bow as close to specs as possible, at least for starters.

I wouldn't be pulling any hair out over the draw weight. Repeating what I often do " That's what limb bolts are on the bow for". If it bothers you that much it's a whole lot easier and cheaper to take a turn off the limbs than it is to fork over the bucks to get new arrows and go through a tuning session again.

Another way to drop the weight is to take a few twists out of the string and cable to reduce the preload on the limbs. In this case the A2A will get a little longer and the brace height will get a little lower, but if the bow shoots OK then so be it. It won't be much anyway.

I can't remember, but you didn't by chance add the CCS to the bow did you? This in itself will raise the draw weight about 5# if you didn't get a
1/2" longer cable compared to the rod/slide combo. Besides, if yur draw length is only 26" or so like mine I would not worry about a few grains of arrow weight. You're not stressing the limbs as much as a person with a longer draw length. Just don't go around advertising it.

Your speed gain is quite normal for what changes you've made. That extra inch of draw length should yield about 10 fps and getting rid of the tube should make up for the other 5fps.

Bowhunter_IL_BT
06-05-2010, 02:54 PM
Hey Barry I did not have a CCS put in the bow. I prefer the old slide better anyway. My buddy at Cabelas did adjust the limbs to be as close to specs as much as he could. The draw length and brace stayed the same. So we went with that. Montelaar thanks for the advice. I figured there may be some variance or error with some scales. It was a digital one. I took it to a local Gander Mountain today with an old fashioned scale (place the bow string on it and pull down) and it had the bow at 73 lbs. My arrows are much closer to IBO with that poundage than 76 lbs. The extra poundage does not bother me at all and I like that few extra fps im picking up :D. I hear there are some people that perform with 4 grains per pound instead of the standard 5 grains per pound (IBO). Mine are no where near 4 grains so I should be in good shape. If I put a lighted tracer nock on the arrow then I make IBO, so that gives you an idea of how close I am with a standard nock.

Destroyer
06-05-2010, 09:05 PM
I hear there are some people that perform with 4 grains per pound instead of the standard 5 grains per pound (IBO).

:eek: I Never go under the AMO standard of minimum 6 grains per pound. 4 grains per pound???? YIKES!!!

Montalaar
06-05-2010, 10:55 PM
You will find a table for AMO arrow weights somewhere in the internet. It states that a shorter drawlength can shoot arrows under 5gr/in but archers with a longer draw should shoot arrows with around 7gr/in to prevent damage to the bow.

A highspeed comparison between two archers with the same bow and different draw lengths showed to us that the vibration produced by the lang drawing archer was severe.

bfisher
06-06-2010, 12:32 PM
You will find a table for AMO arrow weights somewhere in the internet. It states that a shorter drawlength can shoot arrows under 5gr/in but archers with a longer draw should shoot arrows with around 7gr/in to prevent damage to the bow.

A highspeed comparison between two archers with the same bow and different draw lengths showed to us that the vibration produced by the lang drawing archer was severe.

What Simon is talking about here is called the AMO Minimum Arrow Weight Chart. I believe there is one on www.huntersfriend.com. Essentially it does not suggest a minimum according to a given draw weight. It also adjusts for a person's draw length and type of cams.

It's well known that long draw archers store more energy in their bow. This is why they get more speed for a given draw weight and arrow weight. What the AMO chart does is, if you read between the lines, is adjust the arrow weight so that a shorter draw archer can shoot a lighter weight arrow because, not creating as much energy to be stored in the bow also does not release as much energy at the shot. Therefore, the shorter draw archer's bow should not absorb any more unused energy than the longer draw shooter, even though shooting a lighter arrow.

So in layman's terms a shorter draw archer should be able to throw the 5gr/lb rule out the window and shoot an arrow light enough to attain the same speed as a longer draw shooter without undue stress on the bow.

Now pay real close attention to this chart if you should find it. The AMO does not stress any one gr/lb requirement. If you really look at the longer draw lengths it suggests a much greater gr/lb than IBO (or factory) for those with longer draw lengths.

Think about this long and hard and you may see some correlation between the speeds achieved with today's bows and maybe, just maybe a reason for the majority of limb failures. Bows are just getting pushed too hard for the limb technology presently known.

Maybe bow manufacturers would be doing themselves a favor by adapting this AMO chart. I'll tell you one thing that it might change. Maybe some shooters would start shooting bows correctly set to their draw lengths rather than shooing something a couple inches too long just because it's faster. It would also be some justice for leveling the playing field in the 3D circuits.

As for hunting? Who cares about speed? If you're the average eastern hardwoods deer hunter speed doesn't mean squat for 15 to 30 yard shots. A 30 fps increase in speed will only make a difference of about an inch at 30 yards. All the speed is about is bragging rights.

Montalaar
06-06-2010, 01:43 PM
What a statement, Barry. I really like that one and must save it somewhere.

gibson 787
06-06-2010, 02:35 PM
Well explained Baz!

Destroyer
06-06-2010, 07:38 PM
a reason for the majority of limb failures. Bows are just getting pushed too hard for the limb technology presently known

Or maybe its just showing up poor quality control that manufacturers are using in this economic climate. ;)

Chart?
http://www.whitetailfanatic.com/360/rc_ga_arrowweightcharts.shtml

My M-Pro is NO speed cam, no way near it. But I still use the speed cam column. My current arrow weight is 444 grains. Not too far off the recommended 446 grains.


All the speed is about is bragging rights.

For hunting? Would have agreed with you one time Barry, especially when I was 'traditional'. I mostly hunt those wascally wabbits (and some deer) here and a bit of speed, say 250+ fps make a real difference in the the old success rate. An inch or so is a big deal on these little critters.

Bowhunter_IL_BT
06-06-2010, 07:56 PM
Hey Barry here is a copy of the AMO chart. Based on this Im good to go with my arrows since the minimum arrow only has to be 355 grains. Thanks for the info. on this

http://www.whitetailfanatic.com/360/rc_ga_arrowweightcharts.shtml