Duet: What is max rpm that a 0.9 stepper can Reliably turn?

Creating a geared extruder design. I need to make sure I don't over gear. What is the max RPM the Duet can drive a 0.9 degree stepper without missing steps?

Probably a question for dc42.........

For the extruder motor, IMO there is no point is using a 0.9deg motor instead of 1.8deg.

The Duet running RepRapFirmware 1.09k-dc42 can achieve 100kHz step rate, but I suggest you keep the max step rate no more than 50kHz to avoid overloading the processor. If you want to achieve 100mm/sec extruder speed, that means keeping the microsteps/mm below 500.

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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].

Since layer thickness, width and nozzle size can be such large variables, how about we use speed of filament into the extruder as the constant?

As examples, how fast can you send filament into a normal e3d and a volcano in mm/sec for 1.75mm filament? This would be how much filament must be moved with 50kHz. Then you would just make sure your path width, height and speed mean extruding less than the maximum...... I think the max speed of the volcano is 40mm/sec of 1.75 filament?????

As a side note, I will be using the duet on my new mini delta printer too. I know that the 3 motion steppers in the delta take more steps also (0.9 steppers here too...). How hard will it be to run into step speed limitations with the duet?

Quote
patrickrio
As a side note, I will be using the duet on my new mini delta printer too. I know that the 3 motion steppers in the delta take more steps also (0.9 steppers here too...). How hard will it be to run into step speed limitations with the duet?

Max travel speed on my delta using RRF 1.09k-dc42 and 160 microsteps/mm is about 300mm/sec. If you have 16 tooth pulleys instead of the 20-tooth that I have, then your steps/mm will be 200 so your max speed will be about 20% lower.

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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].

i have 15 tooth pulleys...... so 25% lower.....

Does anyone have information on the maximum speed of 1.75mm filament into E3D regular and volcano nozzles?????

I mentioned 100mm/sec extruder speed because that is the fastest speed I have ever configured for retraction. But usually I use 60mm/sec. Actual speed during extrusion is very much lower, more like 5mm/sec maximum with a 0.4mm nozzle.

For a volcano 1mm nozzle, let's assume you use 0.5mm layer height and 1.2mm extrusion width. To print at 100mm/sec you need to extrude about 0.5 * 1.2 * 100 = 60mm^3 per second. Divide that by pi * (1.75/2)^2 and I get 25mm/sec.

Edited 1 time(s). Last edit at 11/24/2015 05:20AM by dc42.

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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].

Just a remark about 0.9° stepper.
IMHO it can be helpful against skipping and stripping filament, when the extruder motion is as smooth as possible.
At least, I found a better print quality, when I changed the driver of my 1.8° extruder from 1/16 stepsticks to decay hacked 1/32 DRV8825.
I assume it will be even better with 0.9° at 1/16 steps.
-Olaf