View Full Version : Matching pulleys

06-17-2013, 12:47 PM
Dear SDP/SI: In matching the pulley size for 10mm ball screws and 3/8 nema motor shafts, I selected 5.08mm and .200 inch pitch pulleys with 15 grooves respectively. Will there be a problem if I use 3/8 belts for them? Thank you

06-17-2013, 01:18 PM

Do you mean 3/8 wide belt or 3/8 pitch, if it is pitch then it is not correct, you have to use .200 pitch Belts, & also mixing the pulleys can some times be a problem as well as some metric Pitch pulleys, have a different tooth profile, even though both you have end up with the same Pitch, they may have a different tooth profile

So they should never be mixed unless you know for sure the tooth profile is the same

06-17-2013, 03:16 PM
You are correct. It is a 3/8 belt. I tried to find a metric pulley with an equivalent id of 3/8, which is the nema 23 motor shaft size. However, I couldn't find one. The belt fits really close in both types of pulleys. I'll write back when I assemble the machine. Thank you

06-17-2013, 03:34 PM

A 3/8 Pitch belt won't even be close .200 Pitch pulleys, .375 Pitch Belt=.175 difference it is not going to work

You should be using 5mm GT2 Pulleys & belts, for what you are doing, You almost always have to bore the pulleys, to suit what you are going to put them on, attached is just for a guide there are many sizes, but don't expect to get one that fits without it being bored to the size you need

07-26-2015, 07:05 AM
You almost always have to bore the pulleys,
That did worry me at first, but I found that even with Chinese eBay pulleys (GT2, 2 mm pitch, 30 T), the rim was really concentric to the stock bore. So boring out to size was quite easy.