Hello Everyone, I am building the Mini Mill (thank you MarkC) but I was thinking of making some changes (trampling on someone else's better engineering choices no doubt!) as the original build requirement was to keep cost low and I believe I can stretch this requirement a little for my own build. The first use of my MiniMill will be on thin brass (1mm thick) to see if I can mark out the hour markings for a watch face but I also hope to be able to mill aluminium too (manufacturing speed isn't a requirement as this is for Hobby use only) up to and including 1cm cut through depth (can be many shallow cuts). Using the original Stepper motor specs as a guide ( 175 oz*in while physically weighing around 1kg ) I thought I would see what alternative Stepper motor types exist and found the following: 3 Phase 1.2 Step : Leadshine 573S15 : Leadshine 3 phase Stepper Motor 573S15 for NEMA23 5A Length 76mm Shaft 8mm Running @ 48v using 3DM580S. (Or if I waiver the weight concern: P Series Nema 23 1.2deg 3-phase Stepper Motor 5.5A 1.8Nm(254.95oz.in)) 2 Phase 0.9 Step : Nema 23 Bipolar 0.9deg 1.26Nm (178.4oz.in) 2.8A 2.5V 57x57x56mm 4 Wires Running @ 48v using DM542Y : Y Series Digital Stepper Driver 1.0-4.2A DC20V-50V for Nema 17, 23, 24 Stepper Motor Tons of 2 Phase 1.8 Steppers like the original OpenBuilds ones so will skip listing anything against this one. I've been trying to avoid the very heavy NEMA 23 motors as I imagine this would cause imbalance on such a small mill and was wondering if people ever balance out the other side with a similar weight? (but I am going off topic). So my question is, should i follow the norm and go with the 2 phase 1.8, dip my toes into 3 phase or turn to 0.9 steps? I will microstep regardless. The final question is on stepper motor manufacturing quality, anyone have a preference between Cloudray and StepperOnline? I am mainly looking at StepperOnline but only because they seem to be mentioned more often. I will be interested to see your responses. Thank you for your time.
More steps-per-mm due to the smaller angle of 0.9deg motors, means half the maximum feedrate I'd go for the 1.8s unless you had a need for the precision (and slower feedrate being something you can live with) of the 0.9s - keeping in mind that you won't see any of the resolution improvement without beefing up the rigidity to be twice as rigid too (deflection: How to calculate V-Slot® deflection ) No comment on manufacturers, but NB do pay note to coil voltage rating (our motors have 3v coils) so you get good acceleration, and low inductance (ours are around 1mH) for lower back-emf that also limits top speed and acceleration - current rating is but one of the many parameters we already spent the time testing, engineering and proving for you In practice, it doesn't make a difference. Extra mass damps vibrations (;
Thank you for the fast response. I guess if I wanted to stick with 0.9 stepper i could try filling in the C beam holes with Epoxy Granite as there are a few threads online about that improving dampening and rigidity. What about the 3 phase stepper notion? Is the 1.2 step not considered a great enough improvement for most CNC builders?
