Machine cutting undersize parts

First off, my first post here. Fantastic machine, it’s dialing in better and better all the time. I’m cutting some 12"x12" panels in mdf to use as part of my clamping table, i’m having an issue where the parts are coming out at 11 15/16 instead of 12". Here are some details:

-Using 1/4" bits, set to 6.35mm in estlcam - actual measurements are around 6.30mm, undersizing is consistent between two different styles of bit (spiral vs straight).

-4mm depth of cut @ 10mm/s

-Drew some test patterns with a pen while getting the machine square with the endstop upgrade, a 500mm line is exactly 500mm as drawn.

-Drew a square to measure diagonals (square test) and results were exactly as they should have been to the mm, so I am confident the machine is drawing to size.

-“Part” toolpath in estlcam was used to cut the pieces, the grid I have set shows the part as 12x12.

I haven’t tried using a smaller bit (1/8") yet to see if the error follows or decreases, I suspect this is software/gcode related somehow but I would like some opinions on other things to examine. Machine photo attached, built basically to spec using recommended software to generate gcode.

 

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Well that is close but if you want better I would suggest a 1/8" single flute endmill and take of the vacuum hose. See if that gets you what you want.

Thank you for the picture! There have been so many questions lately with no picture. A picture saves me a ton of guessing.