Calibration of my x carve

Rookie question what do I need to do to calibrate my machine. I have a design for a piece that requires 8 slots .260 wide and the machine cuts them .040 narrow. I thought that when I set it up with Inventables that would calibrate the steppers. So any suggestions . Thanks ahead of time

Although, that may have to do with assumed bit diameter vs actual.

If this is within spec:

Then you are dealing with system/tool deflection AND/OR actual/assumed bit diameter like Robert mention.

Oh I didnt realize that.So you dont know the answer either

Measure your bit with a caliper. Then you can enter the actual diameter into Easel. Also the search function can save you a lot of grief.