Tram Arm for CNC Router

Inspired by Winston Moy's tramming tutorial, and finding myself without the right size screws for kriista's Tram Arm for CNC Machine , I designed my own that doesn't need any screws, and provided several lengths for you to choose from.

The tolerance should be a bit tight on your bits, but even PLA should have enough spring in it for the jaws to open up to grab your bit tightly. Insert the bit into the arm cutting-edge first (so you can keep your fingers away from those sharp cutting edges), rotating it backwards to help guide it into the slot.

I found that once the bits are installed, there is still a bit of up/down wiggle on the tool. This actually helps by allowing you to make small adjustments in the touch position without having to raise/lower the spindle itself (which is some times hard to get to stay exactly in one spot).

If you want a longer/taller version from the 3 I've included here, feel free to access the source CAD at Onshape

If you don't have a 3d printer, you can buy one of these tram arms from Dan at PwnCNC (I don't get a cut, he just makes nice stuff).

Note: The photo is of a slightly older version of the design, but gets the idea across.