Draw Board Concern About Accurate Poundage

[meyerske]

I have a draw board and I noticed something that I'm concerned about. The post that the grip rests on allows the bow to pivot during the draw. In other words, the string D-loop is above the pivot point of the grip, which causes a moment (torque) on the bow and so the riser is not perpendicular to the direction of draw during the draw cycle.

My concern is that since the riser is not perpendicular to the draw, the poundage will not be correct. In other words, it takes more to draw the string on an angle than it does to draw perpendicular to the riser.

Thoughts?

I'm considering putting a second post in the board to keep the riser more perpendicular to the draw...

[Takeum]

I tend to want to strap my Envy down as well when I draw the bow,, JUst so it stays straights and doesn't try and jump the post,,, Perhaps bungy cords or something would work,,,Or like you stated,, another post, or two,,

[KDS]

I have a draw board and I noticed something that I'm concerned about. The post that the grip rests on allows the bow to pivot during the draw. In other words, the string D-loop is above the pivot point of the grip, which causes a moment (torque) on the bow and so the riser is not perpendicular to the direction of draw during the draw cycle.

My concern is that since the riser is not perpendicular to the draw, the poundage will not be correct. In other words, it takes more to draw the string on an angle than it does to draw perpendicular to the riser.

Thoughts?

I'm considering putting a second post in the board to keep the riser more perpendicular to the draw...

Watch this video,,,,,,,,,,,,,

http://www.youtube.com/watch?v=5GJ6fVV3RfM

How's the Ice?

[cclingma]

Interesting, very interesting. Just when I thought I knew something about bow setup.

[meyerske]

Watch this video,,,,,,,,,,,,,

http://www.youtube.com/watch?v=5GJ6fVV3RfM

How's the Ice?

Ugh! I have dial-up and can't watch videos! :violin:

My wife loves her Ice! Got lower poundage limbs on it.

[Maybee-R]

Ugh! I have dial-up and can't watch videos! :violin:

My wife loves her Ice! Got lower poundage limbs on it.
Basically the video shows you can draw the bow from the loop or in-line with the grip it doesn't matter with a Binary cam bow. But it does with a dual cam. Hope that helps.

[hntwhitetail]

Yeah... I think 70lbs... is still 70lbs...

[meyerske]

Yeah... I think 70lbs... is still 70lbs...No way. The bow will draw heavier if the line of force is not close to perpendicular to the riser. Try it. Draw your bow at, say, a 45 degree angle to the riser (for exaggeration purposes).

[Elite_Kevin]

You can draw the bow six inches below the nock and then re draw at the nock and the weight will be within .2 of a pound, this has been done a "thousand times" with our load cell.

[marzomi]

No way. The bow will draw heavier if the line of force is not close to perpendicular to the riser. Try it. Draw your bow at, say, a 45 degree angle to the riser (for exaggeration purposes).

The kinesiology from a human body perspective will be different depending on angle therefore making your musculature less or more effective. The bow weight, as stated by the guys who have tested it on binaries, remains the same.

[meyerske]

The kinesiology from a human body perspective will be different depending on angle therefore making your musculature less or more effective. The bow weight, as stated by the guys who have tested it on binaries, remains the same.I agree with what you are saying (I think!). My point is that the bow scale will read a higher weight if the bow is drawn at an angle that isn't perpendicular to the riser.

Maybe Kevin's point is that the bow doesn't pivot much on the draw board and therefore the poundage change is neglegable.

[flybyjohn]

I don't know about all of you, but my hand holds the bow in exactly the same place as the draw board does so the draw board will work for me to measure weight.

[Maybee-R]

I just run a 07 synergy through the draw board. hooked to my d-loop and got 70 .34lbs
did it again level with the grip and got 70.34lbs. NO difference. But I did notice you better be careful.
hooking to the string with out some kind of safe way to keep the bow from turning will ruin your day. A post in the grip only isn't the best Idea I have ever had.:tape2:

I now have two safety posts on the opposite side of the riser just encase the bow turns a little they will stop it. :slap:

[oldbuck]

I have a draw board and I noticed something that I'm concerned about. The post that the grip rests on allows the bow to pivot during the draw. In other words, the string D-loop is above the pivot point of the grip, which causes a moment (torque) on the bow and so the riser is not perpendicular to the direction of draw during the draw cycle.

My concern is that since the riser is not perpendicular to the draw, the poundage will not be correct. In other words, it takes more to draw the string on an angle than it does to draw perpendicular to the riser.

Thoughts?

I'm considering putting a second post in the board to keep the riser more perpendicular to the draw...
Hello,
All the posts are right on the money. When testing bows on my Nock Travel Machine I have found no change in draw weight as a function of riser position. If its off abit from perpendicular to the string it has no effect on the draw weight. These are all great posts and indicate the type of archers we have on this forum.
Thanks to all
oldbuck

[flybyjohn]

I think the key is the ability for the bow to pivot. I could see an increase if the bow was held rigid and not allowed to pivot and you pulled at an angle. But the bow can pivot so the scale is always drawing perpindicular to the pivot point.
I suppose if you watched someone draw a bow and took a picture then made a straight line from the nock to thier hand you would get the same angle that you see in the draw board.

[meyerske]

Thanks for the input. I've learned some good stuff here! I am definitely going to put an anti-pivot post (or two) on my board for safety reasons.

[Maybee-R]

Bump........

[Cliff Orley]

The riser really needs to pivot on one post, to synchro the cams, other wise the rotation of the cams will be influenced by the position of the winch. I always use a D loop to pull the bow back on the jig, even if I take it off after..I learnt the hard way some years back, when letting down, the winch hook slid up the string and dinged the top cam.:profanity:
When using the draw board to check nock travel, than you need the riser held firm, and the winch a certain distance from the bow, so it won't influence the path of the nock...