This is a belt tensioner designed for use with the Anet E12 and the Z-axis rod bearing support brackets I previously made. The idea was to try and make a more compact design that was easily printed and didn't waste too much filament. This will fit on any 2020/2040 based printer but check the fitment and make sure you raise your Z-axis up all the way before you tighten things down so it won't bind on the way up.
Things you will need:
1x 760mm GT2 Belt - A 750mm belt should fit no problem but I haven't tested this yet.
2x GT2 Toothless Pulley 5mm Inner Bore
2x M5x20 Screws - There should be room for any head type for M5.
1x M5x40 Bolt- If your belt is very short you may need a slightly longer screw.
1x M5 Nut
2x M4x12 Screws
2x M4 T-Nuts
2x Z-Axis Rod Supports - https://www.thingiverse.com/thing:3377129
Step 1: Install the idler pulley in the main body with an M5x20 screw. There is room for a nut on the bottom if you prefer but my M5 threaded right into the plastic securely and gravity is only going to help it stay put.
Step 2. Install the M5x40 bolt into the carriage.
Step 3. Wrap the belt around the second pulley, teeth facing in, and install the pulley into the carriage with an M5x20 screw. Again, there is space for a nut if you want but I don't believe it will be necessary.
Step 4. Install your M4x12 screws into the main body and put the T-Nuts on the back side and install it onto your printer. The position shouldn't make much difference but I have mine very close to the right Z-axis pulley so it is as out of the way as possible.
Credit for the knob goes to skartz as I did not feel the need to reinvent the wheel... or a knob.