I Need suggestion with Custom MPCNC Configuration Issues

Software / Firmware General
1

Hello guys! :smiling_face_with_three_hearts:

I have need some help with configuring a custom MPCNC (Mostly Printed CNC) build. I have facing some challenges with my setup and could use some advice.

Setup Details:

  • Frame Size: 24"x24"
  • Electronics: RAMPS 1.4 board with A4988 stepper drivers
  • Motors: NEMA 17 stepper motors
  • End Stops: Mechanical end stops with M3 bolts

Problem Description:
I am facing calibration inaccuracies where the machine’s movements are not aligning with the expected dimensions. For example when I run a 100mm square test cut, the actual dimensions are off by about 5mm. Additionally there is noticeable motor noise during operation which seems to vary with different speeds and directions.

I have double-checked the wiring connections and reconfigured the software settings using the Marlin firmware. Despite these efforts, the issues persist. I suspect it might be related to either the firmware configuration or possible mechanical issues with the frame alignment.

I also check this thread : https://forum.v1e.com/t/help-machine-not-mpcnc-calibration-with-estlcamsalesforce-dev But I have not found any solution for this. Could anyone guide me about this?

Thanks in advance! :saluting_face:

Respected community member :innocent:

2

It sounds like the CNC isn’t moving far enough.

Could be mechanical:

  • Grub screw not tight
  • Did you use 16 or 20 tooth pulleys?
  • Is something like drag chain pulling on the gantrymotion?

Could be software/configuration:

  • Is microstepping enabled?
3

Greetings, Alicia. I see you’ve only just joined the forums about 6 days ago.
Welcome to the V1 community.

Can you post some good high-resolution pictures of your build as a first steps to help us help you?

There are many, many more details about your build that we will be curious about as we go about troubleshooting.

As asked above, what size pulleys are you using? (And are the grub screws tight/ and locktited?)

What CAM are you using to create your toolpaths, what feeds/speeds/DOCs are you using, with what cutter and into what kind of materials?

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4

Is it always about 5mm short, or is the length of the error proportional to the amount of commanded movement?

If the error is always the same amount, I’d be looking for mechanical issues - grub/set screws slipping on the pulley shaft, some teeth missing from a belt, belt stretched etc. A quick visual check for pulleys slipping is to draw a line across the pulley and shaft, then move and reverse direction - the line should still be aligned.

If the error is proportional (e.g. 5mm off on a 100 mm movement, but 2.5 mm in a 50 mm move, then I’d look for a firmware configuration mismatch - number of teeth on a pulley, belt pitch, micro stepping, etc.

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