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Newbe - Calabration advise needed
« on: May 04, 2007, 10:40:23 AM »


I’m very new to CNC machines and G-Code programming, I need some advise.
I have completed my first CNC machine. I’m using Mach3 with Xylotex 3-axis driver.

I’m trying to figure out coordinate systems so that I can create/use g-code programs to make parts and stuff (use my machine).

I’m confused about g-code programs and machine calibration in general.


Is it required and normal to always calibrate the machine to the specific g-code program?

For example, I’m having trouble running the Roadrunner program; my machine is always going out of bounds. And I don’t know how to home my machine to the correct starting point so the program will run correctly.

Or is there a general calabration process that will solve all these problems ?
If so, where can I find a clear tutorial on how to do this ?


I have limit switches, it looks like some of the X-3.8999 stuff is always going to trigger my limit switches. What do I do. I’m confused.

I have reviewed the setup on my mach3 software, but I’m confused as to the general nature of what is going to be required to calibrate my machine, or as to why I can’t run the roadrunner program (and other programs correctly).

Thanks for helping.

Offline Chip

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Re: Newbe - Calabration advise needed
« Reply #1 on: May 04, 2007, 01:14:10 PM »
Hi, Deleteallusers

If you've set your Steps Per , Vel. and Acc. in Motor Tuning for 1 unit of measure, Whether Inch or MM, Then your fine.

Load Road-Runner, To the right of your DRO's (Program Run screen) you'll find Scale, Set at +1.000, Click on the +1.0000 and enter 0.25,

Enter for each Axis as needed X, Y, for sure , This will scale the road-runner by 1/4 size, if it doesn't, Scale it down more,

Most all G-code files you create will / should be sized to fit on your table.

Hope this Helps, Chip

Offline Graham Waterworth

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Re: Newbe - Calabration advise needed
« Reply #2 on: May 04, 2007, 05:06:47 PM »
Do you wish to work in inches or millimetres?

If you move the X and Y axis into the middle of the work area and zero out the X and Y dro's at the top of the main screen.

Then load a pencil or a pen into the spindle and set it so it will draw on paper fixed to your table.  zero out the Z axis dro.

You can run one of these programs and check your sizes.

This will draw a 2 inch square

G20 G40 G90 G18 G80
G01 X-2. F10.

This will draw a 50mm square

G21 G40 G90 G18 G80
G01 X-50. F250.

Its not going to tell you its accurate to .001" (.025mm) but it will tell you if you are a long way out.

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