stepconf is off 50%

Motor steps are 200 (1.8*)
Microsteps are set to 2
Pulley Teeth 1.2:1
Leadscrew pitch is 8TPI

Driver’s microsteps are set to 2
Bipolar series stepper motor
Driver model is KL-4030

Hi Everyone,

When I run my Linuxcnc program my actual step distance is twice the software distance?? Please advice.


Thank you kindly for your help,

Alex

So from your description of your machine it sounds like it should be either 3840 steps/inch or 2666.66. depending on if the larger pulley is on the screw or the motor.

If those are not the numbers that work for you, then are you certain of your settings on your stepper drive, or the pitch of your screw?

As Todd says the most easy answer will a simple mistake.

Double check the dip switches, this driver will do single step, a lot of them have a minimum of 1/2.

8tpi would be quite fine for a ball screw or even an acme thread.
Check it is not a double start 4tpi thread for instance ( seems they exist )
Both would give you 100% over movement

regards

Dear Todd and ArcEye,

I rechecked the following:

1. Your number 2666.6666 is what my .ini file is using. The larger pulley is on the motor.

2. Stepper driver setting for 2 steps per 1.8 degree is 0 1 1 for switches sw1 sw2 sw3. Sw1 is at position down (0) and the other two switches are up (1).

3. Vice versa the stepper driver setting for 16 steps per 1.8 degree is 1 0 0. If I had reversed the setting on the driver then I would not be off by a factor of two.

4. Motor datasheet has 1.8 degree/step or 200 step per rev.

5. I do not have another motor driver KL 4030 to swap out and check to see if the driver is defective.

6. I will install a different brand to see if I get the same result.

Thanks ArcEye, I learned new thing about the double start thread but unfortunately, my thread is a common garden variety 8TPI.

I will work on it and when I find my mistake I will let you know.

Thank you kindly for your help.
Alex

Is it going to 2x or half as far as it should?

Try putting a piece of tape (like a flag) on your screw and make sure if it is turning 8 full turns for a 1 inch move.

Try setting the steps/inch in the ini to 400, and see if the motor moves one complete revolution with a 1inch movement command.

Somewhere there is a factor of 2 miscalculation, just have to hunt it down.

Or if you don't really care, just set the steps/inch in the ini to what ever works and call it good enough.

. I will install a different brand to see if I get the same result.

Don't bother with that, it will be in the settings somewhere.

If you change your ini file so that
SCALE = 1333.3333
does that correct everything?

As Todd says, you can just do that (I might not be able to leave it alone until I found the problem )

regards

Dear ArcEye,

Yes at SCALE = 1333.333 everything is correct. I will save the problem for another day.

Thank you again.

Dear Todd and ArcEye,

I did what Todd asked by putting on marks on my screw. One turn on the pulley gave me double the distance. ArcEye is right. This is a double thread screw. I did not check because (blame on it one someone) a mechanical engineer and another experience guy told me that it was 8tpi not a double thread. Maybe the the mechanism on the screw walks double the distance.



Thank you everyone for your help. This fairy tale has happy ending!