Digital Belt Tension Gauge

I saw this thing on aliexpress and I found it interesting. I found it kinda expensive, so I decided to design my own. I like to believe I improved it. Keep in mind that your thread gauge might have a slightly different shape. I included the f3d fine just in case.

I included a model for 9mm and another for 6mm. My aim was so the pin pushes precisely in the middle of the belt. Any of them should do the work just fine, but if you want to go overkill, then print both of them and swap them for the right belt size. 

You can either lock them onto the gauge by threading the 3mm screws directly into the parts, or you can use the bigger hole and add the threaded insert for m3 screws.

You may want to use supports for the smaller parts.

I would recommend to tighten the belt using the sound tool to estimate the right tension, then you can use this tool to accurately match the tension for all the other belts. 

BOM:

1. thread gauge - mandatory
2. M5 shafts, ~20mm long(this is what I had, but 10mm also works: 2 or 4pcs (if you prefer to keep one for each version)
3. 2 or 4 M3x8mm screws - optional
4. 2 threaded inserts - optional
5. Small elastic bands - mandatory

Future improvements planned:

• a version that allows the belt to slide smoothly on the shafts

Note:

1. for an easier understanding, extend the thing at maximum and do the zeroing. this way, higher(nevative) values indicates looser belts
2. slide the shafts end behind the belts and slightly let them touch them as you release the pressure on the gauge
3. For improved accuracy you may add more elastic bands to make the gauge strong enough to counteract any unwanted forces on the belt
4. You might notice slightly different values for each measurement. I suspect is because the belt doesn't slide easy enough on the shafts. I will do some experiments in the future and hopefully come up with improvements. 
5. For improved accuracy, do multiple measurements then make an average. 
6. Disable stealthchop on a corexy. More importantly: DO NOT set any value in between 0 and 99999.  You will get skipping steps eventually.
7. Do a speed test and check for skipping steps or loud noise
8. Do the resonance measurement for confirm if the A and B belts are tensioned corectly
9. Print a 1st layer on the entire surface of the bed or jost in each corner+middle.if that's uneaven, then the bed might not be sitting in a paralel plane to the bottom surface of the frame