GT2 belt upgrade question

The GT5 belts on my printer are showing signs of wear so I am ready to plunge into the GT2 belt idea. I have the belts and two sets of pulleys, one set with 20 teeth and the other with 16 teeth. Both of these pulleys are much smaller in diameter than the GT5 pulleys.

My question is how do I calculate the steps/mm that will be needed for the .h file?

All of the posts I have seen have referred to the number of teeth in doing that calculation but the diameter is different from the GT5 to GT2 pulleys for the same number of teeth. Before I go and reverse engineer the problem, does someone have a solution already?

Thanks for your help!

You can use the belt calculator tool on Repetier or this site prusaprinters.org/calculator/

With 20 teeth pulley and GT2 the value to put on .h is 80

Wow! That was fast!

Thanks a bunch for the link to the calculator. I had just finished finding all of the data on pitch diameters to start number crunching…

Just so that my time wasn’t wasted, here is the data I collected:

Stock pulley (GT5 10 tooth) pitch diameter is 15.91mm
GT2 16 tooth pitch diameter is 10.18 mm
GT2 20 tooth PD is 12.73 mm
GT2 25 tooth PD is 15.91 mm (same as stock GT5 10 tooth)

So, if you just want to change to a better belt and don’t want to mess with the firmware settings use a GT2 25 tooth pulley and belt for a better than stock setup.

For my opinion, it’s not a correct thinking to compare diameters.

Do not hesitate to change to GT2 with pulley 20 tooth. Because the values on the original firmware are not exactly correct (try to calculate you will see)

[quote=“thebuglife”]For my opinion, it’s not a correct thinking to compare diameters.

Do not hesitate to change to GT2 with pulley 20 tooth. Because the values on the original firmware are not exactly correct (try to calculate you will see)[/quote]

According to the mechanical engineers I work with, you can compare pulleys by pitch diameter. I had to ask to be sure. Don’t confuse diameter with pitch diameter, they are different.

As a side note, I cannot find any source for a 25 tooth GT2 pulley so it looks like a mute point anyway.

From what I have read and researched it looks like the change from GT5 to GT2 is well worth the effort.

If you know why did you ask ?