On 26 May 2018, at 16:13, Jon Elson wrote: >> > That motor can produce rated torque down to near zero speed. But, a belt > reduction INCREASES torque as you lower spindle speed. In some cases like > heavy fly cutting, face mills, boring, and drilling with large diameter > drills, you need that extra torque.
+1 to that. Lack of low speed torque is a real pain. IMHO belts and pulleys win every time, at low speeds. On my mill I have a 2HP motor with an electronic speed control. I have a flycutter mounted on a 250mm/10 inch faceplate on the spindle of the mill, and it won't cut toffee at its properly rated cutting speed. I can see the electronics trying to compensate for the reduction in speed at the cutter bites, but the low torque just can't cope with the loss of momentum on even a relatively shallow cut. On the manual lathe, with a constant speed 1425rpm 1 HP motor, the same flycutter on the same faceplate, and the spindle set at low speed on the pulleys, that cutter will mangle its way through anything at all without blinking or slowing. And that's without backgear. Electronic speed control is much more convenient, especially when the speed can be controlled by LinuxCNC, but low speed performance is a problem, I find. If a servo will solve that problem, I would happily fit one tomorrow. Marcus ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
