Considering a Duet: Could Use Some Insight (UMO)
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@CCS86 said in Considering a Duet: Could Use Some Insight (UMO):
What would you say the speed limitation of stealth chop 2 is? And what happens when you exceed this? (Skipped steps, resonance?)
In my experience, the issue is skipped steps. That's what I experienced occasionally when I switched my Maestro-powered Ormerod printer from spreadCycle to permanent stealthChop.
The maximum safe speed for stealthChop will depend on your steps/mm and you motors, but I think it would typically be between 50mm/sec and 100mm/sec.
To counter this limitation, the drivers are normally programmed to switch from stealthChop at low speeds to spreadCycle at high speeds. The snag is that when it switches over, you get a slight motor jerk. The higher the speed, the worse this jerk is. You don't want a large jerk to happen during printing. This leads to two possible settings:
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Set the drivers to switch over to spreadCycle at a low speed. So they will be in stealthChop mode when idle and at very low speeds, but mostly in spreadCycle during printing. This is the default in RepRapFirmware.
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Set them to switch over at a speed higher than your highest printing speed, so that they only use spreadCycle during fast travel moves. Or, if you limit the travel speed, they will always be in stealthChop mode. This may be what the Prusa i3 it does in "slow and quiet" printing mode.
HTH David
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Thanks David,
I tend to print mostly under 50 mm/s. If I ever went higher, it would be for infil moves, where a slight jerk for a mode change shouldn't be a big deal.
In regards to the 1.6 amp max current, I am running these steppers to drive X and Y: https://www.omc-stepperonline.com/nema-17-bipolar-0-9deg-46ncm-65-1oz-in-2a-2-9v-42x42x48mm-4-wires.html
They are rated at 2.0 amps. I highly doubt that my Ultimaker Original board is driving them anywhere near 2.0 amps. For a very light print, bowden print head there wouldn't be any issues at that 1.6 amp limit on the Maestro, right?
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2.0A motors is higher than I would recommend for a Maestro, however 60% of rated current is often enough, and some printers use as low as 50%. So a current setting between 1.2A and 1.4A should work. As you said, I suspect that the existing board drives them at much less than 2A.
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Well, I pulled the trigger on the Maestro!
Thanks again for the help everybody!