Hello, I have a 3040 CNC machine, and I am cutting some CNC clamping plates 50 x 20 x 4.6mm acrylic. There is a slot in it, 20 x 6mm, starting 10mm from one end.

The drawing was made in AutoCAD, imported into Aspire Ver 10.5, and the toolpath created with a brand new 1/8" milling bit with 2 flutes, fed 300mm/min and with 0.95mm depth of cut with 5 passes.The G.Code is sent to the UGS Platform on Win 10 64 bit running with 8 GB RAM and 2.5 -3.0 GHz CPU.

When I cut it the overall result each time is the outer dimensions are 0.4mm too large in each X and Y direction, and the slot dimensions are 0.4mm too small.

I have put my 0-10mm dial gauge on both the X and the Y axis, and when jogging the spindle 10mm, coming from 20mm out to eliminate backlash, the dial gauge readings give 10.05mm maximum in either direction.

Can you please suggest how I can get these cuts more accurate? I need the slot to take a M6 bolt

My kind regards,

Jill