I have a rotary indexer with a 3.1 ratio, 3.1/360= 0.0086111111 . The wizard is limited to 0.008611 turns/deg. 0.0000001111 does not sound like much but a movement of 0.008611 turns on the rotary indexer corresponds to an angle of approximately
0.0266 degrees or 0.008762 inches on a control surface with a width of 3 inches.
8 thou of error is too great. Any way around this?
A couple questions before I answer, if I may.... 3.1:1 is not a common reduction ratio, how did you arrive at that number? Your numbers are accurate, but only at full steps, are you running a stepper at full steps? If so, why?
And the reason behind my questions is shown in the chart below. Using 1/8 or 1/16 microstepping reduces the step resolution to the 0.001 range for rotary blanks in the 2" and 4" diameter. That said, if true resolution is an issue you should consider a minimum of 10:1 reduction on a router 4th axis and 50:1 on a mill.
Gary Its belted with a 62/20 gears for 3.1 with 4000 steps per rev microstepping. I built it out of a lathe headstock a few years ago and have been running small parts successfully but recently have had some larger parts with with tighter tolerances and the error was glaringly obvious. I might have to redesign with a additional set of pulleys to get the gear ratio reduced.
Here is a pic with the back cover off to give you a visual.
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suntravel wrote: ↑Tue Apr 30, 2024 1:00 pm
I have 90:1 on my mill with 4000 Steps, works very well.
You can fit a harmonic drive on the stepper for high reduction without backlash.
Thanks Uwe, I have been looking for something with 45:1 or 90:1 and I cant find much. Are you using a planetary gearbox? Do you have a link? How much backlash and are you compensating?