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### Author Topic: Motor Max Speed problem  (Read 7608 times)

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#### Hood

• 25,835
• Carnoustie, Scotland
##### Re: Motor Max Speed problem
« Reply #10 on: February 14, 2011, 11:46:50 AM »
What is the pitch of screws and have you any gearing between motor and screw?
Reason I am asking is I am just wondering what RPM your steppers will actually be running when you are attempting 500IPM.
Hood

#### kb18951452

• 15
##### Re: Motor Max Speed problem
« Reply #11 on: February 14, 2011, 12:19:23 PM »
~1275 steps per inch. I don't know all the gearing details, but i do remember that the steps per is ~1275 (maybe 1272.24)

#### Hood

• 25,835
• Carnoustie, Scotland
##### Re: Motor Max Speed problem
« Reply #12 on: February 14, 2011, 12:49:05 PM »
That doesnt sound much, 200 steps per rev of motor x 10uS of drive is 2000 per rev of motor so your axis moves over 1.5 inches per motor rev?
Hood

#### kb18951452

• 15
##### Re: Motor Max Speed problem
« Reply #13 on: February 14, 2011, 12:52:28 PM »

#### Hood

• 25,835
• Carnoustie, Scotland
##### Re: Motor Max Speed problem
« Reply #14 on: February 14, 2011, 12:53:37 PM »
So what kind of screws do you have? or is it a rack and pinion?
Hood

#### kb18951452

• 15
##### Re: Motor Max Speed problem
« Reply #15 on: February 14, 2011, 01:18:49 PM »
R&P and i don't know the pulley diameters (Only needed to know them when calculating things at the beginning.)

#### HimyKabibble

• 1,687
##### Re: Motor Max Speed problem
« Reply #16 on: February 14, 2011, 09:58:14 PM »
I would guess the problem may well be the Breakout board.  I suspect you're seeing the upper limit of the step pulse frequency it will pass through, and beyond that point the step pulses are "aliasing", so the frequency coming out of the BOB is lower than the frequency going in.  CNC4PC uses some strange pulse-shaping circuitry on their boards that I could see causing that kind of problem if you've got a defective chip or component on the board.  It would be instructive to try temporarily wiring up a different breakout board, or even a completely passive one, just on a single drive, and see what happens.

Regards,
Ray L.
Regards,
Ray L.

#### kb18951452

• 15
##### Re: Motor Max Speed problem
« Reply #17 on: February 15, 2011, 01:42:03 AM »
I actually replaced the ICs on this board after i conencted 12v to the 5v terminal.....

Do you recommend a BOB? I'm familiar w/ cnc4pc, and would probably just get he updated version of this board.

#### kb18951452

• 15
##### Re: Motor Max Speed problem
« Reply #18 on: February 28, 2011, 09:45:01 PM »
So. It appears to have been the BOB. Replaced it.

We are having a diff problem now, however.

One side of the gantry seems to be running faster than the other.

I am wondering: We slaved the A to the X, and since then have adhjusted the steps per inch rate for the motors. Is there a chance that the steps per inch isnt getting properly applied to one of the motors? Maybe we need to unslave change the settings, then reslave the motors?