Best timing belt and pulleys type for minimum backlash

[Boyan Silyavski]

I have a belt driven machine. Originally with XL belt, then i upgraded to AT. I wouldn't be too concerned with backslash, as there is no any when tightened properly.

Belt stretch under heavy loads is another thing. However an 0.05mm precision can be achieved doing the following. I made a Mach3 file for every material i cut by cutting and measuring square with a circle in it one pass full depth of the bit and using the Mach3 motor steps adjustment features. So i have a file for wood, plastic and aluminum.
The practical downside of this is if you have bigger machine, you have to make at least 2 files for various sizes similar to your normal work. The file for a 1m piece is different from the file for 10cm cut pieces.

Bear in mind my case is extreme as i use only 10mm belts. I imagine with wider belts it wouldnt be so much of a stretch. Another thing i learned is to use steel braided belts, not the kevlar belts.

AT belt is definitely the strongest from the normal belts, i mean apart from the exotic " special" ones. A bit stronger than the HTD and quite much compared to the XL.

Preloading the belt using a tuner and frequency calculator from their site is the proper way to eliminate belt backslash, i mean if you don't have a very handy device that measures the stretch.

Of course that is valid if the manufacturers tooth engagement and belt design rules are followed.