Mini Bed Level Adjustment

A forum dedicated to the stock LulzBot Mini 3D Printer
unicyclistjoe
Posts: 4
Joined: Sun May 13, 2018 5:28 am

Mini Bed Level Adjustment

Post by unicyclistjoe » Sun May 13, 2018 5:34 am

Is it possible to make adjustments to the level of the Glass/PEI bed? I've had the mini for about 6 months now, and i'm starting to find that the left side, mostly towards the back, is about 1mm higher than the front right of the bed, even after levelling I get a good print in the middle, but a high extrusion in the front and a low extrusion in the back.

b-morgan
Posts: 169
Joined: Fri Aug 11, 2017 8:53 am

Re: Mini Bed Level Adjustment

Post by b-morgan » Sun May 13, 2018 10:42 am

The auto-leveling is supposed to correct for that. Make sure you have the auto-leveling gcode at the beginning of every print (unless you really know what you are doing). The correction factors calculated from the auto-leveling are not stored in the EEPROM so they are lost every time the printer is power cycled.

unicyclistjoe
Posts: 4
Joined: Sun May 13, 2018 5:28 am

Re: Mini Bed Level Adjustment

Post by unicyclistjoe » Sun May 13, 2018 2:20 pm

I use auto levelling for every print, however, when i'm watching the printer start to extrude the first layer, watching the Z distance as the print moves around on that layer, it is hugely noticeable that there is a large z difference between the front and back.

b-morgan
Posts: 169
Joined: Fri Aug 11, 2017 8:53 am

Re: Mini Bed Level Adjustment

Post by b-morgan » Sun May 13, 2018 4:06 pm

Use a straight edge to see if the glass is flat. The distance from the top of the washer to the bed in all 4 corners should be the same. You might try loosening the 4 corners and making sure the bed is sitting flat on the corner pieces. At this point, a call or email to support@lulzbot.com might be in order.

unicyclistjoe
Posts: 4
Joined: Sun May 13, 2018 5:28 am

Re: Mini Bed Level Adjustment

Post by unicyclistjoe » Sun May 13, 2018 6:02 pm

Thanks for the advice. Here's the underside of a print I just completed, the top of the picture is the high side, where it came unstuck from the build plate.
Attachments
unnamed (2).jpg

Galadriel
Aleph Objects | LulzBot
Posts: 227
Joined: Mon Sep 25, 2017 10:23 am

Re: Mini Bed Level Adjustment

Post by Galadriel » Mon May 14, 2018 7:00 am

unicyclistjoe wrote:
Sun May 13, 2018 5:34 am
Is it possible to make adjustments to the level of the Glass/PEI bed? I've had the mini for about 6 months now, and i'm starting to find that the left side, mostly towards the back, is about 1mm higher than the front right of the bed, even after levelling I get a good print in the middle, but a high extrusion in the front and a low extrusion in the back.
By "after leveling" do you mean just the printer going through the autoleveling process? If so you may try verifying that your x-axis is sitting level using these instructions:
https://ohai.lulzbot.com/project/leveli ... e-repairs/

mwester
Posts: 46
Joined: Sun Nov 26, 2017 8:02 pm

Re: Mini Bed Level Adjustment

Post by mwester » Mon May 14, 2018 7:51 am

Check that the four washers are correctly tightened -- I encountered problems on one of my minis with auto-leveling, and traced it back to one of the four washers being loose. This resulted in the bed pushing up on the washer, tilting it upwards -- so the probe in that corner was too high.

The best way I've found is to pinch the PEI/glass bed to the aluminum plate beneath with one hand to compress the flexible mount, then just snug down the screw on the washer. You want it just tight enough that the washer is level against the glass/PEI surface and won't rotate by hand -- any tighter than that and you risk stripping the threads in the aluminum plate (which is not a good thing at all).

I've added checking the washers for tightness (i.e. check that they won't rotate by hand) to my pre-print checklist -- a little loctite might make that unnecessary, but I never seem to get around to that! :-)

unicyclistjoe
Posts: 4
Joined: Sun May 13, 2018 5:28 am

Re: Mini Bed Level Adjustment

Post by unicyclistjoe » Mon May 14, 2018 6:22 pm

Thanks for both replies, I will try both solutions and see how I get on

Avaloncourt
Posts: 1
Joined: Wed May 16, 2018 5:11 am

Re: Mini Bed Level Adjustment

Post by Avaloncourt » Wed May 16, 2018 5:27 am

I am having exactly the same problem with my mini on the left rear side. I've observed some things which have direct bearing on what is happening. Sometimes the level is correct and other times it is not.

When going through the leveling process, the hotend will wipe and then go to the rear left position to begin the leveling process. When the issue with the bed leveling as experienced, the first point in the leveling process, that rear left side, the hotend will drive itself into the leveling plate.

Under normal circumstances, the hot end would tap the plate and then lift and find the plate slowly. In the case when things go wrong, the hot end drives itself down into the plate pushing it downward about a quarter of an inch. It's as if it doesn't even detect that it's touching the plate. It will then lift and then strike the plate again as if it were trying to find the position. It will then move on to the second point, correctly locate it and then move on to the third position. More often than not, at the third position, it will touch the plate, lift, and then begin lowering but decides it can't find the position even though it never gets there and does a rewipe. It then returns to the third position, completes it, and then moves to the fourth position performing that successfully.

After this process is all done, the leveling is not correct.

If I disconnect, power down, restart and reconnect the leveling process will successfully complete. I may get an additional or two additional prints before it starts messing up again. Sometimes I don't even get an additional print before things go wrong once more and I have to repeat the process all over again.

In the end, if it's successfully starts correctly with that first point, things will be just fine. If not, things are never correctly leveled. It is always very predictable that it tries to drive the hotend into the first leveling plate when things go wrong. If it taps the leveling plate and then correctly finds the first point, the leveling will be correct.

dfarning
Posts: 9
Joined: Sat May 19, 2018 3:22 pm

Re: Mini Bed Level Adjustment

Post by dfarning » Sat May 19, 2018 3:46 pm

I would like to confirm that I am getting a similar error with the automatic bed leveling on my refurbished lulzbot mini.

1. The issue is random. Sometime the problem occurs and sometimes it does not. I am brand new to 3d printing so I am still learning the cause and effects involved.

2. Some times auto leveling appears to work. Other times when the extrude head hit the bed washer, it appears that the extruder does not detect the impact with the bed washer as a result, the extruder causes the print bed to deflect downward up to a 5mm.

3. As a result it appears that when then print process starts, the extrude head can be touching the bed hard enough that no filament comes out of the hot end. ( the filament drive wheel is turning so, I believe that it is trying to push filament through the head. Other times, the extrude is a few mm above the print bed. Then the filament kind of falls to the printbed.

David
EDIT - It seems everything works correctly after I fully restart both the printer and Cura software. 4/4 test prints worked correctly. It seems I can create good prints while I continue to debug the larger issue. To be honest, I was getting grumpy that my new printer was failing on most of the job I tried over the last couple of days.

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