Nema 17 - set up speed in Sprinter

Hello everyone,
I would like to ask for a little advice how to set up speed for nema 17 in Sprinter. I use M8 rods and would like to force to spin these motors faster. If I set up AXIS STEP PER UNIT I just control how many spins per mm motor should spin compared with rod I use ?
But what If I want change rotation speed ? For example I have now 1mm per two seconds and I want 1mm per 1s.

yes step /mm sets just that, how many steps is required to move 1 mm.

you want feed rate, controlled by your slicer when producing gcode and the max feed rate in your firmware

Or by your GUI in manual mode.

if you look at raw gcode

eg G1 Z10 F300

move to z 10 at 300 mm/min (5 mm/sec) (or up the the max feed rate in your firmware)

so 1mm/sec would be G1 Z10 F60

Edited 2 time(s). Last edit at 09/21/2014 05:31AM by Dust.

Thank you Dust for information, now I know where I should focus. Thx

One more question, what is the maximum feedrate I can set in arduino for nema 17 ? Now its set to ( define _MAX_FEEDRATE {400, 400, 2, 45}.) So what is the usable maximum number when motors spin correctly?

That depends on your hardware and stepper power

Imposable to say remotely. and best determined by experimentation

Basically set the numbers high in firmware then set them low in your GUI, and try a manual move.. if it moves ok increase the rate in your GUI, till you find the rate at which it breaks. Put your highest working value back into your firmware.

Each axis will probably be different.

NB be careful. some GUI's use mm/second other mm/min and the firmware is similar parts are in mm/sec and other parts in mm/min

Edited 1 time(s). Last edit at 09/21/2014 07:55AM by Dust.

Ok, is it possible somehow damage hardware or motors itself if these numbers are high ? What is the sign that speed is for motor too high ?

no you cant damage the motors like this.

The motors will buzz, but not rotate.

Thanks Dust,
I have made some test with feedrate and it works pretty well. Thanks