Calibrating steps/mm

[Jddt]

When I completed the steps/mm calibration and I run code, like the homing code, then the distance is completely wrong.

Any advice.
Thanks

[mrehorstdmd]

What type of mechanism? What distance is "wrong" when homing?

Steps per mm is normally a simple function of the pulley teeth, belt pitch, and steps/rev of the motor.

[Jddt]

I am using external drivers. All my final drive pulleys are HTD5 20 tooth. I do not get any consistency with the distance the axis move.

See calculations below.

[dc42]

If you are using external drivers then you will need to use a T parameter on the M569 commands for those drivers, because the default width of the step pulses generated is fine for the built-in TMC2660 drivers but too short for almost all external drivers. See https://duet3d.dozuki.com/Wiki/Using_external_stepper_motor_drivers#Section_Configuring_the_Enable_polarity_and_step_timing.

[Jddt]

Settings I am using now. Can the T setting influence the accuracy of my steps?

M569 P0 S1 ; Drive 0 goes forwards
M569 P1 S1 ; Drive 1 goes forwards
M569 P2 S1 ; Drive 2 goes forwards
M569 P3 S1 ; Drive 3 goes forwards
M569 P5 S1 R1 T2.5:2.5:5:2.5
M569 P6 S1 R1 T2.5:2.5:5:2.5
M569 P7 S0 R1 T2.5:2.5:5:2.5
M569 P8 S0 R1 T2.5:2.5:5:2.5
M584 X5 Y6 Z7 E8

[dc42]

If the T values are too small then you can miss steps.

[nz_andy]

What is the external drive micro step set at? you have 10,000 miro-steps per revolution listed in you post, so micro step setting is 50?

[Jddt]

[nz_andy]

Have you tried using 1/16 micro-stepping instead of 1/50th? if that works that may tell you there is an issue with the signal frequency / pulse width.

[deckingman]

@nz_andy said in Calibrating steps/mm:

What is the external drive micro step set at? you have 10,000 miro-steps per revolution listed in you post, so micro step setting is 50?

Good spot. That could well be the OP's problem as 50x micro stepping isn't a supported mode - see documentation here https://duet3d.dozuki.com/Wiki/GCode#Section_M350_Set_microstepping_mode.

[Jddt]

Thanks for noticing the error in my calculation. I am using external drivers and are not using the M350 command.

[Jddt]

@jddt Changed to 128 Micro Steps

[Jddt]

What is the max T values you suggest to be safe?

[dc42]

@jddt said in Calibrating steps/mm:

What is the max T values you suggest to be safe?

High T values will limit the maximum step pulse frequency. I doubt that any stepper drivers need greater than T10.

[Jddt]

The motors started to work properly with a value of T5

[dc42]

According to the datasheet, T2.5:2.5:5:0 should work.