by cvoinescu » Fri Jan 16, 2015 1:46 am
Most drivers need bipolar 4-wire motors, which are the most common. You can use 6-wire unipolar with some performance degradation, and 8-wire unipolar/bipolar motors too. A 4-wire bipolar motor gives the same or slightly better performance compared to an 8-wire motor wired as either bipolar series or bipolar parallel. Very few drivers work with unipolar 5-wire motors -- avoid those.
As for 1.8° (200 step-per-rev) vs. 0.9° (400 step-per-rev), it's all a matter of speed vs. precision. The 1.8° motors are likely to be faster (both because they need fewer, larger steps to move the same distance, and because they're generally somewhat more powerful than similar 0.9° motors), but 0.9° motors have twice the resolution. With the usual belt pulley sizes, say 20-tooth GT2, giving about 0.1 mm per step for 0.9° and 0.2 mm per step for 1.8°, the decision isn't obvious, one way or another. With a laser cutter, the forces involved are small, so microstepping is likely to be effective in increasing the resolution; and speed can be important when raster-engraving or when cutting very thin materials -- so I would probably opt for 1.8° motors.