Re: [CAD_CAM_EDM_DRO] Re: Servomotors & Minimill - do these need speed reduction or not?

The low rapid rate and general lack of torque at high speed seems to be the case with steppers. I'm wondering why anyone would opt to use them. The drives are much more expensive, alot more difficult to configure. Heating problems compared to servos etc. I've just noticed alot of posts with questions regarding steppers and I'm just confused why anyone would use them. There seems to be an abundance of used servos around. One person one here mentioned that "the steppers on his small mini-lathe produced enough heat to fry eggs"

Ron

Jon Elson <elson@...> wrote:
knives01us wrote:

>Several people have reported that it takes 80 oz/in just to move the
>X or Y axis on a well set up minimill with stock leadscrews and ball
>bearing screw end mounts. This can be determined by adjusting and
>oiling everything and then wrapping some cord around the 4"
>handwheel and adding weights until the axis seems to move reliably.
>
>With this in mind, I'd gear down the servos. I used 420 oz/in
>steppers direct drive on all 3 axis of mine and it works fine, but
>the steppers peak out RPM wise at about 40 IPM rapids.
>
>

I have a 4:1 belt reduction on mine, and have run it up to 90 IPM with no
trouble. There's really no need to move such a small machine that fast,
I'm just showing off!

Jon



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