Microstepping Prusa Z axis?

What is the advantage to microstepping the Z-axis on a Prusa Mendel? I have RAMPS 1.3 purchased assembled from Ultimachine, which is set for 16 microsteps on all axes by default. I never thought about it until I today when I was tweaking the steps per mm, and 2700-something steps per mm of Z travel seems like a high number compared to the rest. Would fewer microsteps be easier on the motors or the pololus?

I searched the forum and wiki and couldn't find this answered anywhere.

Mind you, I have no need to change my setup (besides a little extruder steps per mm adjustment). I'm printing 0.25 mm layers in PLA beautifully, and ridiculously fast, with Sprinter/Pronterface/SFACT, and my motors and pololus stay cool to the touch or at worst slightly warm, never missing a step. I'm just curious.

... and a hearty thanks to all of you who have contributed to everything I've built so far, this is an amazing project

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2700-something steps

That's 2560, unless you have something different than M8 lead screws.

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Would fewer microsteps be easier on the motors or the pololus?

Not for the motors or the Pololus, but for the ATmega's computation load. RepRap Firmwares can do somewhere between 10'000 and 30'000 steps/second before getting overloaded, so you might be limited to just 230 mm/min or 3.9 mm/s.

Edited 1 time(s). Last edit at 09/21/2011 05:05AM by Traumflug.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Traumflug Wrote:
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> That's 2560, unless you have something different
> than M8 lead screws.

Yeah, I have 5/16"/18 tpi studding on my Z.

> Not for the motors or the Pololus, but for the
> ATmega's computation load. RepRap Firmwares can do
> somewhere between 10'000 and 30'000 steps/second
> before getting overloaded, so you might be limited
> to just 230 mm/min or 3.9 mm/s.

Thanks, those were the numbers I was curious about. I'll try out lower microsteps and report back if I see any real difference.

I finally got around to turning off microstepping on Z and playing around with max speed. I found that my Z motors are significantly louder when not microstepped; they went from a quiet hum to need-earplugs-and-waking-up-the-neighbors loud. Some speeds are louder than others, in fact I found that the faster I go, the quieter they get. Unfortunately, at a certain speed I start having binding issues (which I've never had before). I'll try 1/2 stepping at a more reasonable hour for a Saturday, and see if the noise level changes.