Belt Tension Tool
by Smidge204, published
A simple lever to check the tension of your printer's belts - or other small, low-tension belts and cords.
Print both parts, clean if necessary and assemble - the hole in lever just slides over the post on the base. Note that the arm of the lever is parallel and aligned with the top edge of the base - this is the "zero" position.
Tension the belt how you like it. This will be your calibration point.
Place the belt in the jaws of the tool and gently squeeze until the lever (point "A") just touches the peg (point "B") opposite the hinge point. The tool is now fully clamped. Squeeze it just enough to the two parts to make contact, and be careful not to pinch the belt between them since that will throw off your measurement!
Use a marker pen or pencil to mark where the bent lever arm is on the base. This is now your reference point - the belt will be in (nearly!) the same tension every time you repeat the test and the arm ends up at the same point.
Use this tool to test your belt tension during tune-ups, if you're re-building or making a whole new machine!
Since the performance of the tool depends very much on the properties of the material and how it's printed, I elected to not put any kind of scale on it. I recommend PLA (which is what mine is made of) since it's not as bendy as ABS. Always check that the lever is aligned with the top of the base before using so you know the lever doesn't have any permanent bend in it, which would throw it off. I am able to pinch the lever all the way down without having it bend permanently so it should be good with gentle use!
If your belts are so tight that you can't get the jaws to close, sand down the bottom of the pin on the lever so the belt is not bent as much.
SolidWorks 2012 files are included.