Hi, I was able to get an access to a Sieg x3 cnc. I have just downloaded a trial of cambam and did some basic shapes ( Circles 100mm, 200mm), I have generated the codes and uploaded it on Mach3. When I did a test run I have noticed that the shapes were under size. I do not know if I made a wrong input ( wrong cutter size.. ), but maybe you guys here can share some gcodes that I could use to test the accuracy of the machine. I do not know how to do gcodes manually :-(

Maybe some gcodes for some circles and squares....I have a 3/16 endmill cutter that I could use :-) I'll use a some wood planks to practice on..

Just use some of the wizards to do some tests, for example the circular pocket wizard, obviously if set up in metric you would need to enter your tool dia in metric.
Other way is just to test each axis from the MDI line by first setting the axis to zero then command a move via MDI and measure to see if it moved that distance. EG G0X10 then press Enter key and the axis should move 10mm.
Hood

I have a Grizzly G0619 (Sieg SX3) and I use CamBam which I highly recommend.

After selecting a circle on the graphics screen and creating a machining "Profile" there will be a configuration table for the "Profile" on the lower left side of the screen.

In the configuration table one of the options is "Inside/Outside" which will determine whether CamBam places the tool path or the cut on the inner side of the circle's circumference or on the outer side of the circle's circumference.

The center of the tool path or cut will also be offset from the circumference of the circle by the distance of the radius of the cutter that is configured in the configuration table by its diameter.

Under sized cut circles suggest that the actual cutting tool has a smaller diameter than the cutter that is configured in the configuration table.