• DIY Draw Board.... with PICS

    When it comes to tuning binary cam bows, or 'slave-cam' bows, a draw board is a very useful tool for checking cam rotation, timing, and sync. Since I own a bow like this, and have been wanting to get into DIY archery tuning, I thought the time was right to build my own draw board.

    It's actually a very easy and inexpensive project. A couple hours of your time and about 40 bucks is all you'll need.

    1 - 2 x 6 plank (about 6-8 ft long)
    1 - trailer/boat winch (found at TSC for $19.99)
    1 - 1/2" ID threaded pipe nipple (galvanized or black, doesn't matter)
    1 - 1/2" threaded pipe floor base
    1 - yard stick (Home Depot has them in the paint section for $0.61 each)
    1 - turnbuckle
    1 - speed link or heavy duty carabiner
    1 - short section of 3/4" ID rubber hose
    1 - scrap piece of rubber or felt

    The build itself is very simple. I started out by measuring on my bow, how high above the throat of the grip were the berger holes... which was about 2". I did this because I wanted to stagger the pipe on the plank from where the winch pulls back... Because when you draw a bow, you're actually pulling from above the grip throat. I attached the pipe base near one end of the 2x6, centering it 2" from the end. At the opposite end, I mounted the winch in the center of the 2x6, but mounted an eye-bolt as a guide just in front of it 4" from the edge of the board (so 2" above the grip throat). This probably isn’t totally necessary, but I felt it would better imitate a real draw of the bow.

    With the pipe and winch mounted, it was time to attach the yard stick. When measuring AMO draw length, it is measured from the throat of the bow grip, plus 1.75". I measured back from the FRONT of the pipe 2” to gain clearance from the pipe base, and then marked a line. I cut the yard stick off at 3.75” (1.75” + the 2” clearance) and attached it to the board, starting at my mark behind the pipe base.

    The gap between the pipe and the winch can vary… Obviously it only has to be wide enough to accommodate the draw length of the bow. I made mine extra long, so that eventually I can attach a digital scale behind the turnbuckle.

    Finished draw board…

    Pipe and base…

    The winch setup…

    The turnbuckle is used to finish the draw on the bow. You don't want to pull to hard into the back wall with the winch... So you use the winch to get it close to full draw, then spin the turnbuckle to bring it back all the way.

    Here are some pictures showing the draw board in action.

    Quick and easy way to measure draw length. Also, notice the green string attached from the speed link around the bow string. This is somewhat of a failsafe… Just in case the d-loop decides to break for some reason.

    Checking draw stops….

    Now here is where the draw board really becomes useful. On these Elite bows, the cams have timing dots on them for use in tuning. In this first picture, the top cam is shown, with the front control cable passing through the THIRD timing dot.

    In this second picture, the bottom cam is shown, with the front control cable passing through the SECOND timing dot and slightly across the third.

    What this is telling me is that my cams are slightly out of sync. I’m still trying to figure this all out, but I believe (correct me if I’m wrong, Milo) the top cam is slightly under-rotated… and I will need to either advance this cam, or retard the bottom cam to fix this issue. This is accomplished by adding or removing twists in the control cables.

    As you can see, this is an easy build and a very useful tool. This type of tuning isn’t for everyone, but for guys that are tired of looking for a good archery tech and want to work on their own bows this is the way to go. Hopefully this DIY thread is helpful for anyone else here that would like to build their own draw board. If you have any questions, ask away!

    This article was originally published in forum thread: DIY Draw Board.... with PICS started by JBrown View original post