LRv4 losing millimeters

LowRider CNC Troubleshooting
1

Hi All,

Ive just finished assembling my 2400x1200 LR V4 (upgrade from Primo). Had a few teething issues with motors dropping out but that is all sorted and the machine is functioning mostly as expected.

The problem is loosing size along both X and Y. Z also might be loosing a little but harder to check over the shorter travel.

What I’m doing -

  • Home X,Y,Z. and set to 0,0,0.
  • Move Y 2300 (from webUI command)
  • Measure actual travel = 2294 (6mm lost)
  • Move Y 0
  • Measure actual travel =2294 (exactly where it started)

Same process with X and Z and at other distances. From what I can tell I seem to be loosing roughly 0.25mm per 100mm both X and Y. Z I’m not sold if I’m losing anything or not.

Otherwise everything seems to function as expected. Running Gcode from estlcam works fine other than loosing mm in the same fashion.

I’m running -

Jackpot CNC (elecrow)
ESP32 (amazon) FluidNC V3.9.1
TMC2209 (lerdge, waiting on some BTT ones)
Configs from V1 Github.

IMG_20250716_124154429
IMG_20250716_1241544291920×1440 254 KB

IMG_20250716_124137702
IMG_20250716_1241377021920×1440 284 KB

IMG_20250716_124229400_HDR
IMG_20250716_124229400_HDR1920×1440 295 KB

Side note - when does one tighten the “cross tensioner screws”. The docs say to leave them out for now. But i cant find when to put them in/tighten them.

Thanks.

3 Likes
2

Nice looking build!

Assuming your belt holders are well anchored, solid, and V1E shop sourced belt is reasonably tensioned, and you’re consistently measuring the same inaccuracy, then, maybe some tweaks to steps_per_mm for X and Y axis in the FluidNC config.yaml will help…

Bartman recently wrote up a nice calibration sequence he (and others) found helpful. Including Step 4 which covers how to improve on the nice 0.25% error you’re currently observing. Hope https://forum.v1e.com/t/complete-lr-calibration-sequence/49819 helps you calibrate and further tune to a tolerance you’re happy with. The process is similar to how we calibrate belt based 3D printers.

Z motion uses leadscrews instead of belts, so less variance concerns. Recommend ensuring your leadscrews are well lubed, and well aligned during assembly, then, you should be good to make some Struts!

Cheers!

1 Like
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Great thanks for the link, Didn’t find that one in my searching. I’ll give it a run through.

Used same supplier of belts for other projects including the MP3DP and PRIMO without issue so I’m assuming these ones are ok but will check.

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4

You don’t need them. Mine are very loose, Ryan doesn’t use any at all. Gravity does it job well enough. :slightly_smiling_face:

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That link was exactly what I needed Aza. Moving exactly as I tell it now. I should have connected the dots doing the same thing with printers, brain wasn’t on that page.
Bit of squaring and tramming then off to cut struts then XZ Plates.

Thanks Philipp I’ll leave them loose.

Tim.

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Mark Aza’s reply as a solution when you’re satisfied all is as it should be, please.

Really glad it’s working as expected for you.

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7

Glad my thread on calibrating was useful to you!

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