# Machsupport Forum

## Mach Discussion => General Mach Discussion => Topic started by: lucky021 on May 05, 2010, 03:50:06 PM

Title: how to setup the steps per unit in config->motor tuning
Post by: lucky021 on May 05, 2010, 03:50:06 PM
I got confused here, what I should setup in "steps per": 1600 or 32000?

My unit is "inch", if I setup "steps per" to 1600, it means it takes 1600 steps to make one inch movement, right? but in my system, I use 1600 step/rev (200*8 micro-step) motor and 20 tpi (20 threads per inch) rod, so does it mean I should put 32000 in "steps per"?

To imagine, my motor can be set to 125 micro-step with 25000 step/rev, with 20 tpi rod, the number will be 500000 steps per inch, then the maximum velocity will be only 3, which looks weird? So in my real case, 1600 or 32000?

Thanks.
Title: Re: how to setup the steps per unit in config->motor tuning
Post by: Overloaded on May 05, 2010, 04:46:43 PM
32000 is correct for the steps per.
The max velocity is limited by the kernel speed selected.
Kernel =25k / 500,000 = .05 x 60 = 3 in. per min
25k /  32,000 =  .78125 x 60 = 46.875 in. per min
60k / 500,000 = .12 x 60 = 7.2
60k /  32,000 =  1.875 x60 = 112.5 in. per min.
Title: Re: how to setup the steps per unit in config->motor tuning
Post by: slip stream fox on December 17, 2012, 08:54:46 PM
Hey Guys,

I got the same set up with Lucky 021.  I got everything set up and be using over 1 and half.  But my Feed rate is to fast. I keep breaking bits and reducing my original speed of feed cut down by 80%.

My question is how can I get my motor tunning slower.  i'm using 45K on the freq. and step per 40,000..... 67.5 in per min. ........ 5.5 Acelleration per in.

Where am I going wrong Here?

Tim
Title: Re: how to setup the steps per unit in config->motor tuning
Post by: Hood on December 18, 2012, 03:08:57 AM
Sounds like you are doing your machining at rapid speeds if you are snapping the bits, you should be using G1's in your code and controlling the feed with a F. eg G1X10F2

Hood
Title: how to setup the steps per unit in config->motor tuning
Post by: Fastest1 on December 18, 2012, 05:12:22 PM
Why not set it up at 25Khz?
IIRC, Doesn't a 1/4-20 travel 1" in 5 turns? If so.
200 x 8 x 5= 8000.
Title: Re: how to setup the steps per unit in config->motor tuning
Post by: woodspinner on December 18, 2012, 05:57:34 PM
actually, 1/4 - 20 moves 1" in 20 turns.

so, 200 * 8 * 20 = 32000

John