Slowed retraction speed after changing to 0.9 Degree Stepper

Hi,

Today I have tried to change my extruder's stepper motor (1.8 degrees) with a 0.9 degree motor. I have doubled the steps/mm (it is at 3587 now at 1/64 microstepping). It is extruding nicely but the retraction speed is probably halved. I tried to increase the retraction acceleration, the retraction speed in the slicing software but these changes didn't increase the speed. Am I hitting the pulse generation limit of my electronics (Re-Arm)? Would going down to a lower microstepping degree help with that?

Also, I was planning on changing the X and Y axis to 0.9 degree motors but if there is a problem with me hitting pulse generation limits, it won't probably be possible.

Thanks...

Why not work out what pulse rate your extruder is demanding?

Step rate = stes_per_mm * retraction_speed_in_mm_per_minute/60

Example: 3587 steps/mm * 3600mm/min speed / 60 = 209.241 KHz

I believe the default maximum pulse rate for Smoothieware is 100kHz, but you may be able to change that in the configuration.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Why not work out what pulse rate your extruder is demanding?

Step rate = stes_per_mm * retraction_speed_in_mm_per_minute/60

Example: 3587 steps/mm * 3600mm/min speed / 60 = 209.241 KHz

I believe the default maximum pulse rate for Smoothieware is 100kHz, but you may be able to change that in the configuration.

How about Duet Wifi? My Duet arrived yesterday so I'd like to know if I'll be able to use 0.9 degree motors.

By the way, do you have any recommendations for my transition from reArm-RAMPS to Duet with panel due? I'll check the web site but I think I'll need to replace all the Dupont connectors, modify my BLTouch by adding a resistor, and do some wiring work for the connection between the 12 volts PSU and the Duet. Would you also advise to change my PSU to 24 volts or change the X,Y and E motors to 0.9 degree motors?

The Duet WiFi and Duet Ethernet can drive one motor at 380kHz, and 3 motors simultaneously at 180kHz.

I recommend using 24V power if you choose 0.9deg motors, otherwise you may not reach the speeds you want. See How_to_work_out_the_power_supply_voltage_you_need for how to work it out.

DuPont connectors will fit the Molex connectors on the Duet. You need to change the order of the wires on the endstop connectors, but that is easy to do.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Do you really need to use 64 micro steps? I would try to change micro stepping to 16.