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clivemgriffiths
08-02-2023, 12:37 PM
I have mach 3 running on generic Chinese cnc mill which has been calibrated for axis movement. With gcode output from Aspire, I tell it to create a square 25mm x 25mm x 5mm deep, the square comes out at 23.6mm square and 4.9 deep. I have measured axis movement of 150mm using MDI and that measurement is spot on. I'm thinking there's a setting in mach3 that I am missing. Any help greatly appreciated.

m_c
08-02-2023, 08:17 PM
If the axis movement is accurate over 150mm, then it's very likely a combination of cutter/machine deflection, and backlash.

A DTI would let you know where the problem lies.

clivemgriffiths
09-02-2023, 11:55 AM
If the axis movement is accurate over 150mm, then it's very likely a combination of cutter/machine deflection, and backlash.

A DTI would let you know where the problem lies.

Thanks for the reply m_c, can you explain how to use the "DTI" in this situation please?

m_c
09-02-2023, 06:57 PM
Dial Test Indicator.
Set it up so it's against the spindle cutter, then try push/pulling the cutter to see who much movement you get.
Then also use it to manually jog the machine and see how much backlash there is in each axis.

clivemgriffiths
10-02-2023, 06:18 PM
Will give that a try, thanks for your help.