for those who have no other way to check their TOM w/ MK7 extruder bed for being level
Print out the the two plates. drill out the 3mm holes and insert a 3mm screw. find a compression spring to load into the hole in the main body. this pushes down on the arm. You could also cheat with a rubber band used on the other end- any way to get down pressure on the right hand side of the arm.Break the tabs off of the arm that are at the end, they are there to keep the arm down on your build platform. once assembled, place the index, the funy thing with the dash marks on it, on the z platform all the way to the right side. Next slip the body and arm over the extruder mounting plate , wth one clip to each side of the motor.
Heat your bed to working temp.
Using yur control panel, lower your z axis until the reader nub on the arm hits the bed and the arm raises a little.
Move your bed until the nub is in a corner. set your jogs to 50mm and move to another corner.
if you are using a three scew adjustment (you should) then level between the two corners then do centerline front to back.
The index is notactually calibrated to anything, but the end of the arm is 20 times farther out from the axis then the nub, so a .005 chnge at the nub equals a .1 change at the end of the arm. All that you are looking for is no motion in the end of arm.
Worked on the machine that i tried it on. I trued it with my machinists gauge, and this one said flat. I skewed the bed and this set-up showed it out. when leveled carefully with this, it came in looking fine when double checked again with the fancy gauge. hoe this works for you well enough.