Slowest Z-axis Step Rate
May 03, 2017 03:04AM
Hi all,

I have a RAMPS 1.4 Arduino Mega 2560 board, and A4988 driver, set to 1/16 microstep. For my application, I would like to be able to move the Z-axis arbitrarily slowly (4-5 steps per second). I have a NEMA 17 stepper attached to it. Is it possible to go that slow? I have read that there is a 32-step per second limit, but cannot quite figure out why that's the case. Currently, when I try to go much slower, I seem to be defaulting to around 32 steps per second. I am controlling the board using Repetier on a Mac, and am sending G-codes directly using the Print Panel. Thanks!
Re: Slowest Z-axis Step Rate
May 03, 2017 04:09AM
moving that slow I wouldn’t expect any movement half the time... 1/16th only "works" if there is momentum

set to 1/4 microstep max, that should be achievable at slow speeds
Re: Slowest Z-axis Step Rate
May 03, 2017 05:18AM
Firmwares that do not implement precise pulse timing - in particular during acceleration - have minimum movement speeds. AFAIK all 8-bit firmwares fall into this category. You may be able to locate the minimum speed definition in the firmware source, reduce it, and recompile.

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Disclosure: I design Duet electronics and work on RepRapFirmware, [].
Re: Slowest Z-axis Step Rate
May 07, 2017 06:04PM
If you really need a slow speed add a reduction (easiest is a small closed loop belt with 2 pulley sizes).
Re: Slowest Z-axis Step Rate
May 10, 2017 10:46PM
Another quick option, using cura, would be to check the spiralize the outer contour, vase mode, this will increase the height of z constantly verrry slowly

Normally used when printing a vase, so it never just goes up at each layer, but constantly spirals up
Re: Slowest Z-axis Step Rate
May 19, 2017 09:28PM
Surely, unlike the Z and Y axies, the "speed" of the Z axis depends on the amount of time it takes to print each layer of the print before it steps up to the next layer? If the area of each layer is large, the Z axis will take longer before it steps to the next layer once the current one completes. So you'll get a 0.2mm step (for a 0.3mm nozzle size) on completion of each layer. In this respect, the "speed" of the Z-axis depends on what you're printing.

Or am I missing something? confused smiley

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