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"Homing" Mach3 without using home switches
« on: July 16, 2008, 12:11:01 AM »
From the document, Using Mach3Mill...

"If you do not provide a 'home switch' then you will have to jog the axes by eye to a reference position. The home switch for an axis can be at any coordinate position and you define this location."

The mill on which I am trying to set up Mach3 does not have home switches. The documentation does not further explain how to "eyeball" a home position. Does anyone know how to do this? If there is already a forum thread covering this topic/issue, could someone give me a link to it?

Help would be GREATLY appreciated!

Offline jimpinder

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Re: "Homing" Mach3 without using home switches
« Reply #1 on: July 16, 2008, 12:56:51 AM »
The Mach 3 DRO's provide two different readouts.

With the Machine Co-ordinates button pushed (the surround is lit) then the DRO's are displaying machine co-ordinates. These are the co-ordinates the machine uses to keep track of itself. If you have home switches fitted, and pressed the "Ref All Home" button. the machine would visit each switch in turn and stop there, All the DRO's would go to zero. The machine would therefore know exactly where it is.

You cannot alter machine co-ordinates, and they will only zero by pressing the RefAllHome button. It is unlikely that such a position would be any use when machining (it is usually off to one side of the machine) and is only for the machine's own reference. "Offsets" are provided in the table of "Fixtures" to move the table (or cutter) to the correct position for work - and in a prfessional machine shop, the machine would be "homed" to the switches, then the appropriate offset would be called for whatever program was being implemented.

With no home switches fitted, or activated, you will find you can press the RefAllHome button and the DRO's will zero anywhere at all.

If you press the Machine Co-ordinates button, so the light goes out, the DRO's are now displaying program co-ordinates. This is the display that you use with your program. The first thing is to find out where your program says that the 0,0,0 position is. On a mill this is normally (but not always), at the bottom left hand corner of the workpiece, with the cutter resting on the top of the piece.

If this is your 0,0,0 position, then mount your workpiece, and jog the machine until all three axis are in the correct position, then zero the three DRO's (In program co-ordinates they will zero - machine co-ordinates will not). You are now ready to start.You can move the axis anywhere you wish now, provided you do not touch the DRO's and the machine will return to that position and start the program

If you look at you Fixtures table - "Config/Fixtures" you will see figures have been entered into G54 offset. This is the offset of your work position from your machine position, and you can see that if you fit home switches, you can, just like the "pro" machine shop, have the machine zero itself, and use offsets. But then again do we need to ???

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Re: "Homing" Mach3 without using home switches
« Reply #2 on: July 16, 2008, 01:21:43 AM »
The Mach 3 DRO's provide two different readouts. ...

Thanks for your response!

I'll be taking a closer look at what you wrote. Will post again if there are any other questions.