[GrizHFMinimill] Re: I'd like to get your input on my DIY DRO and power feed project.

If you buy the motors Rick Grimm recommended for the power feed, they have encoders on them. About $22 each delivered. What you do with the encoder data is up to you. But, with all the backlash on the mill, those don't seem very useful to me. I think what you want is a feedback loop from the DRO that tells you when to start decelerating your motor so you can creep in on your desired position. The problem is that the cheapo chinese scales are so slow to respond that you will either have to move incredibly slowly to wait for data change/settling from the scale that it's going to be kinda lame. The solution here is a very high end scale with fast ("rapid") response. Those are not free.

It seems that what you want is CNC so just do it. You'll end up spending twice as much time and money doing pseudo CNC and won't have good results.
1. Use ball screws so you can get the backlash out of the picture.
2. Use servo or stepper motors with encoders -- the latter are not easy to find but I think they're a safer solution. When a servo motor looses control voltage, it goes -- full speed ahead. When a stepper looses control voltage it just sits there.

If your setup is nice and tight with no material backlash, you can skip the encoders.

--- In GrizHFMinimill@yahoogroups.com, "Yuriy K" <ycroosh@...> wrote:
>
> Dave,
> I wonder if there is a way to use the steppers as encodes... After all, when you are turning the motor manually, you are basically generating electricity in small distinct pulses.
> Let me play with that idea a bit. :)
>
> Regards
> Yuriy
>
> --- In GrizHFMinimill@yahoogroups.com, "dave_mucha" <dave_mucha@> wrote:
> >
> >
> > A friend has a plasma table and he can input coordinates to make holes, rectangles, etc.
> >
> > something similar would help anyone with scales and power feed. I welcome step of automation.
> >
> > my mini is powered with steppers and can run full CNC .
> >
> > to that end, I have handles on the steppers to manually move them. no problem, but since they are manual, I have no feedback for position.
> >
> > I am running a ball screw for the Z but using the ACME screws for the X and Y. I do not do production and the mill has a serious design flaw about getting lube under the main table.
> >
> > Dave
> >
>

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