New to CNC stuff.

The output of a g-code file in mach3 does not reflect the original dimensions as specified in cambam.

I'm pretty sure everything is setup in MM on both ends.

It seems like i read somewhere that that some feedrate (or other) settings need to be the same within both programs but I havent figured out which settings need to match yet :(

maybe my steps per inch setting (in mach3) is incorrect?

Any help would be appreciated.

Hello Cornelius,

My suggestion is to first verify that you have Mach3 calibrated correctly by doing some simple tests.

In Mach3, zero your DROS, then go to the MDI window and enter some simple gcode commands like:
G21 (this will put you in MM mode)
then
G1 X100
Then measure the distance travelled with a vernier to confirm that it is indeed 100mm.
(you might want to get ready with the e-stop button if your machine tries to head for the hills ;D )
Then try your other axis (G1 Y100, G1 Y100).

If this doesn't do what you'd expected then you need to change your motor tuning parameters. There is also an automatic calibration routine in the Mach3 setup screen you might want to check out.

If the above all checks out, you could then create a hand coded gcode file using a text editor. Something like:

G21
G0 X0 Y0
M5
G1 Z-1
G1 X100
G1 Y100
G1 X0
G1 Y0
M30

Try cutting that in some foam or MDF and measure the resulting square.
Don't forget to take into account the cutter radius. So if you used a 6mm cutter, the above square should be 94 x 94 mm.

If that all checks out then it's time to start checking things in CamBam.

I hope that helps and good luck!

Will try this and report back. Thank you much for the info