Cutting a square and circle, but they are out of measurements or oval

LowRider CNC Troubleshooting
1

Hi,

Just got the LR3 squared, but the cutting are getting somewhat strange. I tried to cut a 50mmx50mm square and a 50mm diameter circle. The square had as final dimensions 47.5mm (in the X side) and 49.5mm in the Y side. And the circle was somewhat oval with 48mm in one side and 49 in the another.

Any ideas? Thank you!

2

Hey Leo,
could be a few things: Grub screws for instance, or the belts being not tight enough (had that problem with my Primo), maybe the strut plates are missing and it is flexing a little etc.
Did you try conventional milling with a finishing pass? If not, I’d recommend that as a test as well.

3

See if you can “wobble” the router from the lower end. See if you can rock the core on the x rails.

Mike

4

Hello @mbamberg and @Tokoloshe . Thank you for the support. I did some things and now I’m able to cut square and circles are circles. For future reference:

  1. I have tighten the belts
  2. I have included the front strut plate (was only using 2 struts at that time)
  3. I had changed the steps per unit in the Marlin (which can be used using M92 followed by M500 or compiling the software). Regarding this last step, i recommend this read: https://teachingtechyt.github.io/calibration.html#xyzsteps
1 Like
5

This seems questionable… The steps per (mm) should be fixed based on the diameter (number of teeth) on the drive sprockets, and should be constant for any stock LR3 (unless you bought your drive sprockets from another source and they are not the standard diameter)

6

Hi, this is not a stock LR3. At first, I was using 200 200 800 config for x y z in MArlin, but the machine movement was in incorrect dimensions. So I had to change this option.