Mach3 question regarding machine coordinates and offsets

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Mach3 question regarding machine coordinates and offsets

Post by Mofosheee »

I hope that I am on the correct forum to ask this question and my apologies if I am not. Please direct me to the proper forum. .

New to CNC with a machine with Mach3 installed. Machine came with limit switches.

My understanding is that when I "Ref All" machine travels to limit switches and stops reading; x=0, y=0, z=0. The machine is now at home or machine zero.

My intent is to go to some convenient place on the cutting area and run a program without hitting the mechanical stops or limit switches. Therefore offsets are required.

How does one find a logical "program zero" or "part zero" and declare that position to Mach so that the program will run from there without hitting the limits or stops? And how does one recognize if a program will exceed the limits of the switches or cutting area before it is ran?

Hope this question makes sense, Thank all in advance.


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Re: Mach3 question regarding machine coordinates and offsets

Post by Greolt »


I suggest you go to this link and watch some of the videos.

The one called "Homing, Limits and Offsets" will be of particular interest.


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Re: Mach3 question regarding machine coordinates and offsets

Post by zeeway »

Well, that video would not load for me, so here's my version...

After I installed the table on my machine, I ran a routine to machine the table flat. So when I attach a piece of material to my table top, and that material is smaller than the flattened portion of that table top, I know my machine can reach any part of that material.

So with that in mind, here is my process.

1. I will typically design with zero in the center of the work piece, and on top of the material.
2. Attach material to table on flattened portion of table.
3. Hit "ref all home", your machine should travel to its home limit switches and set the machine coordinates to 0-0-0. There should be a button under your digital read outs (DRO's) on your Mach 3 screen that is labeled "machine coordinates" - when you click on this (and the little red indicator light is lit), the DRO's should read zero for x and zero for y.
4. Move the machine so that the cutting bit is in the center of the material. Write down the "machine coordinates" of this location in case you have to reestablish the center.
5. Zero your machine to the top of the material, and click on the "machine coordinates" button again (so that the red indicator light is not lit), so that you can see the table coordinates. Zero the table coordinates by clicking on the x,y, and z buttons beside the DRO's.
6. Load your g-code.
7. Turn on router.
8. Press start.
9. I keep my finger near the stop button while the machine is running.


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Re: Mach3 question regarding machine coordinates and offsets

Post by mrmfwilson »

The video worked for me and is very good. Just a tip... Instead of writing down the machine coordinates in case of a crash, after you zero out all the axis, go to the Config menu then to Fixtures and select Save. This saves the settings for all the offsets into a file. The default offset is 1. If the machine or software crashes you can restart Mach, Ref All Home your machine and the offset 1 will be ready to go. You can check this by selecting Go To Zero. This will move the spindle to the current offset (1) to zero on all axis. Be careful and ready to stop the z-axis when you go to zero to avoid slamming the tool into the material if something is not set correctly. I usually stop the Z axis and check it manually.


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