Paul, Thanks for doing some testing on your mill. It never occurred to me that increasing the Period would produce a smoother pulse train. I had reduced it a few days ago to 7usec to get rid of following errors. I did play around with it set at 10usec this morning but I didn't see any improvement, it seemed like I could hear more jitter coming from the motor. I have a big old HP digital scope upstairs I have to try to bring downstairs to test the setup. I'll be happy if I can get smooth 25,000 steps/second. Is there written instructions somewhere and the proper steps to download/install latest emc packages using apt-get? Regards, Jim
Dug out my little Sherline and ran a few tests this morning. The computer is a Celeron 433 with a 440BX chipset, and a C&T 69000 graphics controller (2MB memory running at 800x600), currently with 256M of memory installed. Probably close enough in specifications to do a reasonable comparison of EMC's performance..
The stepper motors on the Sherline are fairly wimpy little NEMA23 rated at 134oz-in running from a unipolar driver - Not the best combination for maximum performance.. About the best I can achieve is 25ipm with a 7.5uSec base period before the motors start squawking and I loose steps (some 6.7KHz). Reducing period to 15uSec, and the maximum speed increases to 30ipm. [Sherline uses 16000 steps per inch when using their driver box].
Hooking up a scope, I see a pulse train right up to 240ipm or 64KHz with a 7.5uSec period. There is a fair bit of jitter which could explain the lower max speed. At 15uSec, the pulse train is much smoother with little noticable jitter, but maximum frequency is limited to 33.3KHz.
I would suggest hooking up a scope if you can get your hands on one, quantifying the jitter and selecting a period to suit - I can run at 7.5uSec, but jitter is a problem, the same at 10uSec. 15uSec produces the better results when using quickstep, but your milage may vary.
Regards, Paul.
--
From the Klingon book of C: Klingon function calls do not have 'parameters' - they have 'arguments' - and they ALWAYS WIN THEM.
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