Let-Off adjustment

[mnwild14]

I just purchased a 05 Martin Phantom bow from an archery shop. For some reason it seems like there is no let-off on the bow. I know he checked the draw weight at the shop when he was setting things up. Is there a way to enable/disable the let-off or am I missing something? I am used to an older bow with very little let-off. I know when I was first looking at the bow I noticed the let-off.

[harvey lee]

My Mathews has a cam for a set let off.I do not believe you can change your let off without changing your cam.I dont know about a Martin but I would believe you cannot turn your let off off.I would take the bow back to your dealer and ask him what is wrong.

[TomBow]

Let-off is a function of the cam. The shape of the cam will determine the let-off and most cams are draw length specific, some come with a moveable draw stop so you can tweak your draw length to your exact preferred specs. Example: If the bow comes with cams that are spec'd at 28" draw length, the cam's spec'd amount of let-off (say 80%) would be achieved with the draw stop at the center or "0" position. If you moved the draw stop to a shorter than 28" draw position, the cam would not roll over the full amount so the resulting let-off would be less than 80%. If you moved the draw stop to a longer than 28" draw position, the cam would roll over more and would result in a greater than 80% let-off. One way to verify your actual let-off would be to put the bow on a bow scale and watch the reading as you push the bow down to full draw. The scale should read the max amount of poundage before full draw and then a lower poundage reading when you reach full draw.

If you are getting no letoff, the cams on your bow may be spec'd for a longer draw length than you are drawing so you may not be reaching the point in the cam roll-over where the let-off starts to take effect. This is odd but possible. You should verify that you have the properly spec'd cams for your draw length. Some bow cams reach let off very near the end of the draw cycle or close to full draw. I don't believe you can "turn let-off off". I'd take the bow in to the shop and have them check it out.

Make sure the bow and cams match your draw length. It is fairly common for shooters to be set up with a bow that has a longer draw length than they should be shooting. I shot for over 10 years myself with a too long draw length. The correct draw length will have you shooting correctly and more accurately than one that is too long, or too short for that matter.

Best of Luck.

[harvey lee]

Very well explained.Everytime you change one thing on your bow you will change something else.

[Deitz Dittrich]

Very nice post and answer tombow

[mnwild14]

I will have to contact the archery shop, I thought maybe there was something simple I was missing. He did lengthen the draw length from 29 to 29.5.

[DooWap]

Sometimes you can tweek those draw stops in a way that it feels as if you have little to no let off. I find it's best to set the pocket as small as possible while still achieving an acceptable letoff for the smoothest and fastest shots.

[BLACKJACK]

Good explaination Tom!!!

[mnwild14]

Thanks for the information. Tom's explanation explained it. I wasn't expecting the %let-off change from changing the draw length.

Thanks for the help. My archery shop is over an hour away, so it was easier to ask the question on here. I assumed I was missing something stupid.

[mnwild14]

The reason I was having trouble noticing the let-off is becuase the only spot you can notice the let-off is at full draw, but before the adjustment it was probably at about 2/3 draw. From what Tom is saying this is expected after changing the draw length. It also sounds like it is preferred to have as minimal amount of distance from full draw to the let-off point as possible, in which case I don't think you could get any better than the way it is set-up. Is this true, or is it preferred to have the let-off come in at about the 2/3 draw point? Does this have a significant difference in the arrow speed and energy when it hits the target?

[TomBow]

It's a personal preference thing as far as how you want the bow set-up, where you want the let-off to take place. Again, cam design and draw-stop setting will determine where in your draw the let-off will take effect. When bows are reviewed in magazines, the reviews often include a graphic called the "draw force curve" which is a graph of each inch that the bow is drawn and the holding weight (draw force required) in pounds relative to those inches of draw. This graphic shows how the cams are designed relative to let-off.

Sounds like the adjustment, if my theory holds true, was to move the draw stop to a shorter draw length bringing it closer to the point of let-off.

Bottom line is if it feels good to you, enjoy it the way it is, if not, change it.

Here's hoping we all put DEEElicious venison in the freezer this fall! Cheers!