Layout of MPG's

[devers6]

For a long time, I have used a single MPG along with a rotary switch for axis selection for my Grizzly SX3. This worked OK, but I eventually got tired of switching between axes; and sometimes I ended up moving the wrong axis when Mach3 missed a switch. So I decided to move to 3 independent MPG's using my existing ZBot for Z, and a pair of Oak/Grigsby encoders for X and Y. I have these electrically connected now using my Smoothstepper and all are working fine.

However, I am now faced with having to lay these out on a control panel in a way that will be easy to grab the dial for the axis needed to adjust. The first idea would be to just lay them out inline horizontally:

X Y Z

or vertically:

X

Y

Z

I am leaning towards separating the Z dial so it is a little easier to find, such as

X

-----Z

Y

or

-----Z

X---------Y

(forgive the dashes - spaces don't work in aligning text in posts)

Before I committed to drilling holes in a panel, I thought I would solicit ideas from this group. I haven't seen any commercial CNC machines, but a lot of photos I have seen have simply had a single MPG. On those that do have more than one MPG, how are they laid out? If you were using 3 MPG's on a regular basis, how would you like to see them arranged?

Thanks for your feedback and ideas.

Dave

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[Al_The_Man]

I have rarely seen a CNC machine with more than one MPG, the only exception I can remember was LeBlond Lathe that had MPG arrangement on a lathe to simulate manual X & Z axis with the HW's.
You may find you are grabbing the wrong MPG is just as possible as overlooking switching the selector switch when using a single MPG?
Al.

[devers6]

The biggest problem I found was that Mach missed a lot of switches between axes. My rotary switch worked fine most of the time, but about every 10 or 20 switches it would end up on the wrong axis. If I was just roughly moving around, it was no big deal; but I often used the MPG as a way to do "manual" milling; and I ran the risk of marring my work if the axis didn't switch as intended. It made it so that I would have to either double-switch to ensure the axis was selected correctly, or check the screen to see which LED was active. In any event, it slowed me down.

I would suspect that the main reason for having only one MPG is expense, but my additional encoders only cost me $15 each on Ebay so that is no issue. The only downside is that they are not detented; but I have a way to correct that once I settle on positioning.

[SCzEngrgGroup]

If your MPG is missing switches, it probably isn't doing the axis switch in a very robust way. The selected axis should present a state input to Mach, not a momentary indication (unless you're using Modbus, which also should not have the problem you describe). The MPG I use has 8 dedicated signals - four each for two four-position rotary switches. One selects functions, the other axes. Mach never misses a change on either, because it reads the state of both switches before doing anything. Rather than applying a complicated, expensive band-aid, you should address the root cause of your problem.

Regards,
Ray L.

[george4657]

My thought on building an MPG was to put the Y on the front, the X on the side, and the Z on top so it matched the handles on the machine and I would not have to think of which one to use.
George

[devers6]

Ray,

I fail to see where $30 in parts, using 3 inputs on the Smoothstepper provided specifically for MPG use, constitutes an "expensive, complicated band-aid". Having a single MPG and an axis selector has always seemed to me to be the equivalent of only having one handwheel on a manual mill, and moving it around to the axis needed to move at any given time.