[CNC43711]

risking to flog a dead horse: I didn't find the answer with the "search"

I bought a complete industrial gantry of eBay for my plasma cutter.
The belt drive needs a torque of about 5.5 kgcm = 76ozin to get moving.

I measured the required torque by winding a cord around the axle and filling a suspended bottle with water until it started moving.

Would a 3Amps 354oz.in/22kg.cm stepper be sufficient to yield 300ipm without losing steps? How do I determine how much margin on torque I need? After all, It needs to accelerate and the power-chain and other cables will give resistance.

[UUU]

How much water do you have to put in the bottle to get 300ipm?

[Eurisko]

Here's a link to a thread that should clear things up a bit.

http://www.cnczone.com/forums/showthread.php?t=31815

[CNC43711]

How much water do you have to put in the bottle to get 300ipm?

Sorry, I was out of town for a while. If I weight it down with 3kg it travels the full meter in under three seconds: so 8kg.cm yields 30cm/s (110oz.in at 700ipm)

At this speed, the stepper RPM would be 90. Still in the contant torque zone for most motors.

From that perspective 260oz.in motors seem plenty powerful to me. How much headroom do I need for torque ?

Also considering that adding a plasma torch, cables and Z-axis will make everything heavier and causes resistance.