[Bdi4emc-help] Max speed

Sat Mar 4 19:31:45 CET 2006

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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