Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: McYoda on September 08, 2008, 03:17:18 AM

I like how to calculate the step for Mach when using step motors. I plan to build another new machine using servo motor and gear rack.
The equipment would be like this.
Servo Motor RPM = 3200
Gear Rack = 20 DP
Pinion = 20 Teeth
GeckDrive = 320
Decoder = 500 CPR
Gearbox/belt = 9
I think that is everything I need. How do I get the steps for Mach?

What are you meaning by the Gearbox/belt = 9? is that a reduction of 9?
Without any gearing then 1 rev of motor moves 1 inch, one rev of motor is 2000 pulses (500 x 4) so that is what your steps per unit will be.
If you have a 9:1 gearing then it will need 9 revs to move 1 inch so Steps per would be 2000 x 9 = 18,000.
Hood

Thank you for the clear explanation.
What are you meaning by the Gearbox/belt = 9? is that a reduction of 9?
Without any gearing then 1 rev of motor moves 1 inch, one rev of motor is 2000 pulses (500 x 4) so that is what your steps per unit will be.
If you have a 9:1 gearing then it will need 9 revs to move 1 inch so Steps per would be 2000 x 9 = 18,000.
Hood

in this calculation, how many step per do we need to turn this servo 3200 RPM ?

Depends what line count your encoder is.
Hood

if we have 2000 line encoder,, how many step per do we need to turn this same servo motor 3200 RPM

If its a 2000 line encoder then that is 8,000 in quadrature so 8,000 x 3,200 = 25,600,000 pulses per min/60 = 426,666 pulses per second (426KHz)
If it was a 500 line encoder then it would be 2,000 x 3,200 / 60 = 106,666Hz (106KHz)
Hood

i understood that i'll need 426Khz for 2000 line  8000 in quadrature for 3200 RPM ! but what will be the "step per" in this calculation ? ( 8000 ? )

It all depends on what the pitch of the ballscrews are and if you have any reduction between the motor and the ballscrews.
Hood

i didnt mean any movement of axis.. i just mean, how many "step per" do we need to turn motor 3200 RPM with 2000 line encoder.. we need totally 426,666 KHZ but.. what could we set "step per" from motor tuning to turn servo 3200 RPM ??

If you are calling one rev of the motor as 1 unit then 426,666/3,200 will be the steps per unit.
Hood
Edit sorry thats wrong, if 2000 line encoder thats 8000 per rev so if one rev is one unit then its 8000

again a little confused !!! cant we turn this servo continuous 3200 Rotation Per Minute ?? or 533.333 Rotation Per Second ?

if i set 8000 to "step per" it means that it will turn 3200 RPM right ? (for this calculation)

If you set the steps per at 8000 that means when you command a move of 1 unit per minute the motor will turn one revolution in one minute and the pulses sent out will be 8,000 per minute.
If you command a speed of 3,200 units per minute then that will be 8,000 x 3,200 = 25,600,000 pulses sent out per minute or 426,666 pulses per second.
Hood

Is this a spindle motor?