Originally Posted by pminmo  The question I would ask is what is the requirement mechanically. It's one thing to spin a stepper at such a rate, another as to the mechanical forces and loads encountered. If youre using leadsrews, you need to consider wip. If your moving any weight, you need to consider starting and stopping forces. |
Indeed. I've ordered a small desktop cnc with .1" lead screws. Not expecting whip as the largest possible unsupported length would be less than 14". I'm very limited by the choice of control box, limited to 5-8K pps (don't ask
). This means that 1000rpm = 100 ipm on this particular machine. Lets pretend I can get 120 ipm or 2 ips. 2 in/sec * 200 steps/rev * 10 rev/inch * 2 pulses/step = 8000 pulses/sec. The x axis (one containing z carriage) is the only one that needs high speed and high acceleration. The Y axis can be slower and have low acceleration (due to the application). The Y axis is the one with the highest load as it needs to move both the x axis gantry and the z axis. Force is limiting to my acceleration. Acceleration is limiting my ultimate speed because of the short gantry. I won't be sure how much everything weights and how much screw friction I have until I get the machine. Once I get everything spinning and working right, I'l likely ditch the slow control system and get something with a lot more current and pps capability.
Still, any suggestions on low inductance, low current motors would be appreciated.
John