Carbide Create grid measurements coming out inaccurate in actual carve

[iboothroyd94 (Ian Booth)]

I’m creating a 30" measuring board, and using simple polylines that automatically ‘snap’ to the vertical grid measurements in carbide create. When I go ahead and carve the project, everything appears to be fine, but when I compare it to an actual ruler, the carved measurements slowly taper wider than their technical measurements, resulting in it being off by 1/16" by the time it reaches 30". 1" through 14" are pretty much right on the money, but 15" through 30" is where it starts to taper off

I’ve run the project on multiple pieces of wood, rechecked the files, recreated the files from scratch, and everytime it just comes out slightly inaccurate. I’ve checked it with different measuring tapes, different rulers, etc - same result each time.

I know it’s not off by much, but when creating something for the purpose of measuring, you want it to be on the dot!

Any suggestions on what might be causing this? Thanks in advance!

-Ian

[iboothroyd94 (Ian Booth)]

Additional photo for reference

[WillAdams (William Adams (Carbide 3D))]

Is this an SO3, 4, or Pro?

Did you calibrate for belt stretch?

Calibrating the machines over long distances

The typical technique for machine calibration: https://my.carbide3d.com/faq/belt-stretch/ depends on precision measuring tools, and is limited by the reach of the tools in question. EDIT: It also depends on access to the MDI — if using Carbide Motion v6 it will be necessary to enable this in Settings | Options: [image] It should be possible to cut strips from a suitable blank of material, one along each axis — so we set up a square file which matches an available blank of material: [ima…

[iboothroyd94 (Ian Booth)]

Much appreciated Will. I’m thinking this should do the trick as I’ve never calibrated for belt stretch, I’ll give that a go tomorrow.

It’s the Shapeoko Pro, first CNC machine for me, so I wasn’t aware it was even a thing! Thanks again