Would using a stepper worm gear arrangement to turn the Z shaft keep it from falling with the power off?

Quote
madmike8
Would using a stepper worm gear arrangement to turn the Z shaft keep it from falling with the power off?

Yes, the only issue is with the cost of the worm gear set.

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What a about an aluminum disc and neodymium magnet (maybe from a broken hard-drive). It could act as an eddy current brake: [en.wikipedia.org]

Alternatively, shorting or loading z-stepper coils when power is removed will use the stepper to damp the fall too (it might be done with a relay that when de-energize will connect the load to the coil and remove it when power, or stepper enable, is back on).

For eddy current to appear, there should be a move, while the case here is to prevent the move It might be that the effect of implementing such stuff is that the printing platform will slowly come down, the speed being actually established by design. I think the same story apply to the alternative way.

I suggested it to slow down the fall, not to keep it still . For keeping it still without power use a brake for the stepper, but if you keep the z-motor powered at all times the fact that the bed falls after shutting down the power is only a problem if it falls very fast and then crashes badly at the bottom (shock absorbers may be an easy fix for that too).

Alternately, if the stepper used has a gearbox, it might be enough to keep the bed in place without power. And using a belt(or fishing line) almost calls for some reduction gear on z-axis stepper to keep a good resolution on that axis.

Edited 2 time(s). Last edit at 08/14/2014 05:41PM by misan.