[skylanehku]

The recommended steps per when setting up is 2000 on the motor settings, yet when you do a measured movement using the calibration in Mach, it will recommend a much higher figure like 25 or 30 thousand steps. Also with two identical axis it will give a vastly different setting.????
Terry

[UniqueMachining]

Terry

Perhaps a little more detail would help.
What machine, model.
Stepper or servo motors........
Generally the machine comes pre-set with steps per set to match the pitch of the ball screw. This is a theoretical mathmatically calculated figure but is usually reasonably close. Further tuning is recommended to obtain the best accuracy possible. Have you queried the manufacturer or distributor?

As an example i
I have a Novakon NM-200 (Stepper version)
The steps per were facctory set to 10,160. (X,Y,Z)
Further tuning resulted in various numbers ( if memory serves) ranging from 10,168 to 10,174.

Just depends on your equipment.

John

[skylanehku]

Thanks for the reply John, my machine is a home built desk top router, running Kieling motors 425ozin with a Gecko 540 and 48volt power supply, acme 1/2by10 lead screws, I was just curious why when doing the travel measurment with calipers it comes out to such a higher number to be entered into the motor tuning screen than the recommended starting point of 2000 and why with two identical axes ( motor leadscrew etc. ) the results can be so different.
Terry

[keebler303]

A G540 is 2000 steps per rev.

Your screw sounds like 10 turns per inch?

That means you need 2000*10 = 20,000 steps per inch in mach.

They should be the same for multiple axes if they all have the same screw and motor and ratio between the screw and motor.

Matt

[skylanehku]

Hi Matt I understand what your saying, but when I do a move with the actual distance measured it calls for a higher number to be entered in the motor tuning screen and my x and y come up with a different number with the same motor and screw.??
Probably not a big deal, just curious as to why.
Terry

[keebler303]

If everything else is the same, they should be the same. Something is wrong.

Check that your couplers are tight, etc. Hard to comment on what could be wrong since I have no idea what your machine looks like.

Matt

[Bubba]

Also, don't forget the lead screws have a tolerance in their pitch. Depending on the screw, this could be up to maybe .009"/ft. And IF you have any backlash, this could make a difference in the measurement.

[skylanehku]

Thanks Bubba, your probably right on, I can relate to the older than dirt, I was 73 when I first started this venture.
Terry

[keebler303]

.009" per foot is .00075" per inch.

At 20,000 steps per inch (theoretical) that is only 15 steps difference. That means that your two axes should be the same within 30 steps (if one has positive error and one negative error).

I would not call 30 steps "so different".

If you are doing the calibration correctly, backlash should not come in to play. You should always be moving in the same direction when you do the calibration.

What are the actual numbers you are getting? The bottom line is that it doesn't matter what it is set to as long as your parts come out correct, however there should be a logical way to determine if your numbers are reasonable.

Matt