Do Open Loop Steppers Need A Warmup?

Today is my day for asking silly questions. I was re-writing my spindle warm-up routine and this thought occured to me…I had assumed that because there is a holding current to the (original open loop) stepper motors that generates at least some heat they don’t need to be exercised while my spindle routine is running. Is that a safe assumption, or should I be moving the steppers around to warm up while warming up the spindle?

Interesting! I could see that from a technical standpoint. I wonder about the approach from a safety perspective. Are you using an enclosure? Would you exercise the Z stepper as well?

There are some built-in “stepper warm-up” moves just from jogging the machine around, homing it, loading stock, and probing. I can’t say I’ve ever heard of someone warming up the motors that move the gantry, but it could be a thing.

Spindle warm-ups are certainly an industry standard for industrial machines. Curious - what did you modify in your spindle warm-up program? And what spindle are you running?

I have written a spindle warm-up routine as well, and also one that moves my axes their full range at increasing velocities. I am doing both of these more to get the bearings and rails lubricated and the oil evenly distributed, but I imagine it warms the steppers as well. From my research this is more important with expensive, highly accurate CNCs where they want to avoid temperature becoming a factor and impacting parts milled to micron tolerances.


In my experience in industry the concern is mainly centered on mechanical functions, i.e. run functions to ambient temperatures to eliminate dimensional drift. The majority of work from a hobby CNC does not require precise dimensional control so I believe axis warm up would actually provide little benefit.
On the other hand, I move each axis vigorously before each session too.

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