Milling Machine: Use Stepper, MPG etc for "powerfeed"

General CNC
1

Hi
New here - so sorry if I post this in the wrong place or such…

I’ve built a few CNC machines, inlcuding a full 3-axis Milling machine (that uses UCCNC for the controller) as well as a CNC Plasma Cutter based on MyPlasmaCNC

However one thing I want to do is this:
I have a conventional milling machine, where I’d like to motorise the Z-Axis.
But not a full CNC control.
What I’d like is a basic (can be arduino based, the simpler the better) control box with a rotary MPG, a selector for resolution (speed range), an overrider “FAST” button and an on/off switch.

The mill in question is a RF45 Clone (Optimium) …
it already has a motor on the Z… however this just lets you “quickly” move the Z and down, but can’t be used to achieve any significant fine control.

I have a massive 6Nm Stepper Motor from another project that I’d use in place.

But I have pretty much no idea how to approach the control system I need.
Any recommendations?

thanks
Daniel

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You can hook up an on-off switch for enable, a SPDT switch for direction, and hook the MPG directly to STEP on the stepper driver.

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The word “massive” triggered my reply. Keep in mind that if massive also means heavy, the X and Y motors have to get that weight in motion. You will probably also need to change the acceleration and deceleration settings to avoid missing steps in the X and Y motion.

4

MPG == Manual Pulse Generator…
I learned something new today :slight_smile:

And yeah; I was wondering ‘what have video files got to do with this’ for a few seconds there . sigh.

5

A quick thought: I assume the existing motor has limit switches? they will need to interrupt the MPG to maintain hard limits…

Adding a simple pulse counter with a zero button may also be a useful? Though I guess you have visual dials and scales to work to.

6

A Z motor will be stationary, on the Z column of a mill and will not move in X and Y with the table. Occasionally it will be on the head rather than the column, but will still be stationary in X and Y.

7

There will usually be hard stops on travel, and if you hit them while turning the MPG it will just make a really obvious noise; a stepper isn’t going to overpower them and do damage.

The RongFU RF45 is a fairly large class of mill weighing a few hundred kilos. A stepper is not going to pass those hard stops.

And in Z, you are likely to damage a tool in the mill spindle by running it into the stock or vice long before you hit a hard stop in the down direction anyway. :smiling_face:

This is for gross positioning of the head. Fine travel for this is probably being done by moving the spindle in a head that has been fixed in place using gib screws on the back of the head. You move the head to where spindle travel will be in the range you want to cover, then lock the head, then turn a screw to engage a clutch for spindle fine feed, then turn a knob on the front of the head to move the spindle and position it for precise Z.

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