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View Full Version : Calculating rotor inertia and detent torque?



Rogue
30-08-2012, 10:24 PM
I'm fiddling with the motor calc spreadsheet but the stepper specs don't give me the rotor inertia or the detent torque. Is it something that can be calculated or is there a fairly safe estimated value I can put into the spreadsheet to keep me in the right kind of ballpark?

It's 60BYGH301B [link to PDF (http://cnc4you.co.uk/resources/60BYGH301B.PDF)], the Nema 23 3.1Nm from cnc4you (http://www.cnc4you.co.uk/index.php?route=product/product&product_id=66).

Jonathan
30-08-2012, 10:36 PM
Just use the values from Zapp's version of that motor as they'll be very close:

http://www.slidesandballscrews.com/pdf/steppermotors/SY60STH88-3008BF.pdf

Rogue
30-08-2012, 10:43 PM
Excellent! It gives the inertia, is the detent torque something that can be worked out from the given info?

irving2008
30-08-2012, 10:45 PM
Use 840 and 1.1, it'll be good enough...

Rogue
30-08-2012, 10:47 PM
Jonathan & Irving, as always, thank you both!

Rogue
30-08-2012, 11:25 PM
Just out of interest, is the difference between serial and parallel wiring really so massive? I've been playing with the cutting forces figures and while the parallel wiring maxes out at 60N, the series wiring maxes out at 225N! I know that this is a "perfect world" set of numbers that doesn't account for the varying qualities of DIY builds but still, that's a massive jump!

Not that I intend to try cutting anything at those sorts of numbers, of course, I was just interested to see what happened when I fiddled with the inputs :whistle: