Gents,

I'm planning to use two steppers in a design of mine and I'd like to double check a few things before I go on a buying spree:

Stepper 1

Probably a Nema 23 stepper, which will run continuously, but in shorts bursts (so for example 20-30s at a time, with minute brakes between). It will drive a shaft via a toothed pulley, ratio will be 2:1 (stepper being faster than the shaft) or 1:1 depending on how smooth I can get the motor to run or how powerful the motor is. Overall operation doesn't really need a stepper and I'm curious if I can use one as a driver for the shaft? the reason for this is that I can get pretty high torque for not a lot of monies (I'll need stepper control, but I'm using another stepper anyway, so a controller can cover both of these). This might as well be modified to be a DC motor instead. Shaft load will be minimal ie. handcrank levels.

Stepper 2

Needs to be a small unit, so looking at a Nema 14. This will drive an M10 lead screw, which will be used to lower and raise an assembly which weighs around 2-2.5kg via two lead blocks. This one will work a microstep at a time as the assembly needs to be positioned precisely (via buttons I reckon), speed isn't an issue. It will also only work in a rather tight area, 5mm tops of total movement, so with a standard pitch of 1.5mm this will be around 3 turns max. I can get around a 10Ncm torque from these Nema 14 steppers, but I'm not sure it's enough to lower and raise a 2-2.5kg assembly. No cutting forces will be present, there might be some small side forces acting on the assembly, but it's supported on two linear 10mm rails, so I guess that will prevent twisting etc. What I need from it is to move and hold the assembly dead in one place, nothing more.

If anyone can suggest torques needed or simply thinks the above is crazy, please let me know:) controller of the motors will be via a custom built electronics unit. I've tried my luck in doing a circuit to run a stepper using LMD chips, but that ended rather badly in the chips overheating (maybe a PCB short or smth similar):



so I might just get a controller of the shelf and do the electronics for the interface instead using a uC. Has anyone tried doing that? controlling a controller and the steppers using a uC circuit instead of a PC?

Cheers,
dsc.