I am currently designing a new machine 2 really and well I am pretty sure I want to go with belt drives instead of screws and racks but I have a few questions. First where can I get the belt and what kind of belt do I need ( I have looked at sdp-si but not sure what to use I saw a cnc with belts that was much smaller than my designs run rapids in the 1200ipm belt drives it had steel lined belts like a radial tire)I want to fix the belt to the gantry and have motor on one end of axis and idler on the other end. Second question I am designing 2 machines first one is roughlly Y3'-4' and X4' second machine is Y4' and X8' or Y5' and X10' numbers are cutting area will belt drives with large steppers or servos work on this size machine? I am looking at rapids in the 600ipm and higher ( want to be in the 1000'+ range).

Thanks
Bearwen

I have been studying the belt drive area quite a bit. A great resource for information and an on-line calculator is www.brecoflex.com. I would look carefully at the AT style belts, the special teeth version to minimize backlash, and possibly the information on trolley arrangements. The on-line calculator is great for belt selection and force requirements.

A some what not so obvious item to belt drives is the increased radial load that is placed on the stepper motor bearings, and the increased sensitivity of the design to stepper motor shaft / bearing tolerances compared to screw drives. There actually are not that many brands of motors that specify substantial radial load and tight tolerance. Interestingly, some of the better ones appear to be from Kelinginc, which has a forum section on cnczone. Take a look at their higher end nema 34 size motors data sheets, as well as anaheim automation's 34 R series and pacific scientific 34 size motors.

About 1/2 of my postings on cnczone have been questions or information about belt drives, so if you are interested, you can search my posts for a real newbie learning about belt drives, and the very good responses from others here on the forum.

This is where I got my belts and stuff from for mine.
http://stores.ebay.com/HUBBARD-CNC-INC

Here are pics of my setup -
http://www.cnczone.com/forums/showthread.php?t=39813

I am still learning and modifying the machine. The table where I place my work is not level, will work on it next weekend. But other than that it is pretty accurate.