Timing pulley question

[pstockley]

I need a 4:1 Reduction for the leadscrew on the lathe I am converting. I wanted to go with GT2 style pulleys. The largest pulley SDP/SI does for 5mm pitch by 15mm wide belts is 72 grooves. So to get a 4:1 I would need 18 grooves on the motor pulley. This is OK but the problem is their 18 groove pulley has .25" bore and I need .5" for my servo. Looking at the drawings, there isn't much meat there to bore out especially since you can only get them in aluminum.

You can get a 120 groove GT2 pulley for 2mm pitch by 9mm wide belts. Would this be adequate for a Z axis on my hardinge lathe?

[Al_The_Man]

Yoy should try the Misumi Catalogue, I believe you can bore up to 29mm on their L type 18t pulley.
Al.