Yet another LR3 Z Leveling Issue

LowRider CNC Troubleshooting
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Post

After 3 days of trying to level my LR3 Z axis I’m about ready to tear it apart and put my LR2 back together. I don’t get the expected results after entering M666 and M500. It seems like it either doesn’t change or it gets worse. If I try reversing what I did it only changes a bit.

I am using the Rambo board and the steppers are from V1E. I previously posted about my issues with one of the Z steppers seeming weak but I didn’t get much help in resolving that so for now I have to help both sides up when homing Z. I have confirmed all the suggested fixes in other posts about the same issue.

However my main problem now is getting Z leveled. I am following the instructions in the documentation. I home Z, probe (using a V1E touch plate), record the results, repeat, move to the other end and do the same thing. My results are usually a difference of 1.3-1.7. I have tried entering the offset with both plus and minus values but again it either stays the same, gets worse or doesn’t change.

Are these M666 changes cumulative or are they separate offsets. How do I get back to what I started with if the change doesn’t do anything?

Also, when I home Z now it raises up until it contacts both switches, backs off, raises back up slowly until it closes the switches and then drops a little. Is that drop the offset that I have entered?

A thought just came to me as I was trying this yet again. Where are the Z steppers supposed to be connected on a LR3 Rambo with endstops? I followed a picture on the site for a dual end stop Rambo but I thought I heard somewhere that the z connectors are in series. If that’s true how would they adjust individually? I have them connected to the Z connectors per this picture:

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This seems consistent with what is happening to me. Both sided drop an equal amount after it homes.

I have the endstops connected as Z1 to Z_MAX and Z2 to X_MAX.

I started here:

A difference of 1.28 with the left side Z1 traveling further. I entered M666 -1.28 M500. I then got a difference of 1.28 again.

Then:

A difference of 1.7 with the left side Z1 traveling further. I entered M666 -1.7 M500. I then got a difference of 1.86.

Then:

A difference of 1.28 with the left side Z1 traveling further. I entered M666 -1.28 M500. I then got a difference of 1.28 again.

So I tried entering positive values and the last 2 tests gave me 2.37 and 2.4 2 times in a row even after entering the values and saving them.

What should I do? I’m pulling my hair out.

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I having the same issue!

I started my build a few weeks ago and successfully cut the struts with some small issues with the Z axis being uneven. After reassembling I was able to zero the Y axis and add an offset using M666. I was able to get Y to within 1mm on a 24 x 48 table. When I try the same thing with the Z axis the M666 adjustment seems to get applied to both side equally.

I also had an issue with the end stop for the Z axis. The lever arm didn’t contact the tab on the XZ plate before the screw tab hit the top of the YZ plate. I have mangled the end stop lever arm trying to get it to work. It seems the lever arms are too long.

I look forward to hear the responses to your questions.

1 Like
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The second Z needs to be plugged into E1, not the second Z.

That is almost certainly your main issue. I don’t know for sure, but I would also expect M666 to only apply after a G28 Z.

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I can’t verify it until tomorrow morning but I think I have Y2 plugged into E1per the picture above. My Y axis seems to be working correctly as I am squared within 1mm. Are there instructions somewhere that clearly show what goes where for this setup on a Rambo? The only reference to Rambo wiring I found in all of the documentation showed the photo above. Could it be that the second Z plugs into E0 since there is no X2?

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https://docs.v1engineering.com/electronics/dual-lr/#wiring

Maybe you have the wrong firmware. It should say something like 515DL. DL means dual for low rider.

M119 also should show you the correct Z2 and Y2 endstops.

The other weird thing though is that G38.2 should only work for dual lr

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Thanks for that link. I’m definitely not wired like that so that’s got to be my problem.

Pretty sure my display says that and I believe I have the correct firmware.

G38.2 works fine.

I’ll correct my wiring tomorrow and report back. Fingers crossed.

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I just tried to do the z leveling on my LR 3 and had a difference of 1.68 (x- max was the furthest)…i then input m666 1.68 then m500 and realized i had the x axis at the x+ max position. Then i homed the z and the x+ z endstop homes and drops a little. I tried inputting M666 -1.68 and M500 to see if it would go back but no change. Is there a video somewhere showing how to do this correctly?

I restarted the entire process now i get a difference of 3.54 and i cant keep the x+ z endstop from lowering down after it homes.

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I think you need a Z, M666 Z-1.68. It is also case sensitive. So only use capital letters.

M666 Z-1.68
G28 Z

Measure again, of that’s good, then M500.

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Success! That was my problem. I had Z2 plugged into the second Z port. Once I changed it to E1 everything leveled out as it should after a couple iterations. This also seems to have solved my “weak stepper” issue. I’m assuming because of sharing the Z driver the current to each motor was halved.

Thanks for the help. Now I can move on to finishing up my spoil board and making chips.

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Good. That all makes sense again. I’m happy you are back on the right track.

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M666 Z? Changes x+ maz side and M666 Z-? Changes X- side