Steppers for Converting Sieg X2 to CNC?

[stirling]

If you ignore the centre taps then you'll be wiring them full-coil bipolar - this will double the resistance giving a rated current of just 1.05A.

You'll get more torque from these motors if you wire them half-coil bipolar. i.e. use the centre taps and ignore two end coil wires. Then the rated current will be the 2.1A stated.

[dazza]

ive got a complete syil kit(electronics only) I may let go if you or anyones interested that's all the electronics plus the nema 34 for the z and the 2 nema 23 motors the electronics are in a makeshift control box(pc case) all wired up just requires the motors to be rigged up,the kit came off an x3 the specs can be seen here
https://docs.google.com/file/d/0B_5R...wtUGxvVW8/edit

[irving2008]

ive got a complete syil kit(electronics only) I may let go if you or anyones interested that's all the electronics plus the nema 34 for the z and the 2 nema 23 motors the electronics are in a makeshift control box(pc case) all wired up just requires the motors to be rigged up,the kit came off an x3 the specs can be seen here
https://docs.google.com/file/d/0B_5R...wtUGxvVW8/edit

There's a big issue with those drivers - the current setting is not via switches but by twiddling a variable resistor while measuring the current in the windings. That's not easy to do without appropriate test equipment, a cheap digital multimeter on DC Amps setting will be wildly inaccurate as it cant sample fast enough

[Jonathan]

There's a big issue with those drivers - the current setting is not via switches but by twiddling a variable resistor while measuring the current in the windings. That's not easy to do without appropriate test equipment, a cheap digital multimeter on DC Amps setting will be wildly inaccurate as it cant sample fast enough

One might be better off in that situation measuring the supply current and voltage to the driver, then since you (should) know the resistance of the motor at low speed, the required supply current can be estimated fairly accurately by considering the rated power. Adjust the potentiometer to get that current. The supply current should be measurable accurately using a cheap meter due to the filtering effect of the DC-bus capacitor.

[Jonathan]

You'll get more torque from these motors if you wire them half-coil bipolar. i.e. use the centre taps and ignore two end coil wires. Then the rated current will be the 2.1A stated.

True at 'high' speed, but rated current through half the number of turns - so less flux which means less torque than bipolar using all the coils.

Useful summary here:
UniPolar vs BiPolar wiring schemes for 2-phase Stepper Motors

[irving2008]

If you ignore the centre taps then you'll be wiring them full-coil bipolar - this will double the resistance giving a rated current of just 1.05A.

Actually the current wired bipolar series is 0.7 * rated = 1.47A, so those drivers would need to be run at 1.2A, but the holding torque is 1.4 * rated.

So assuming they are 1Nm (141ozin) motors:
Bipolar 1/2 coil: Rated 2.1A, run at 1.8A, torque = 1.8/2.1Nm = 0.85Nm (120ozin)
Bipolar Series: Rated 1.47A, run at 1.2A, torque = 1.2/1.47 *1.4 = 1.14Nm (160ozin)

So run them Bipolar Series since you'll get low feed rates anyway due to leadscrew inertia and frictional load...