Why not run Mini without Auto Bed Leveling?

So I noticed when poking around the Lulzbot site that the Taz 5 has “manual bed leveling”. It dawned on me that maybe I don’t need auto-bed leveling and I could save myself a lot of setup time between each print. If the mini never moves from the spot on my desk, why do I need to auto-level the bed each and every time I go to make a print? I can see the purpose if you actually do move the mini around as its portability was intended; hence the handle grip attached to the underside of the top frame. But what if you don’t. What if the machine never moves from it’s home spot. Can’t we then dispense of the g-code that does that whole routine at beginning?


When you remove a part from the bed, you tweak things ever so slightly. Also, after every print, things can start to sloooowly drift so it is good to get a new reference every time. If you don’t believe you will see variations keep the gcode console open and record what the z heights on the 4 corners are measured at during leveling for several prints. I can almost guarantee that you will notice the numbers jump around a bit.

The mini doesn’t have the Taz 5 spring height bed corner adjustment. or the Z endstop target. you certanly could add them in, and thats one of the main reasons some people, myself included have not yet fitted auto leveling to the Taz, but it would be some work to get it attached to the Mini as is.

After owning my Mini for just under a month, the auto levelling system on the mini is the most obnoxious thing I’ve ever dealt with.

I clean the heck of the nozzle with a scotchbright pad when heated before it auto-cleans, and it still presses too hard randomly on one of the washers when auto levelling. It takes me usually 2-5 start attempts before it auto levels correctly where I can trust it not to scratch the PEI.

And of course, before it auto-cleans it retracts the filament, which means if I have to re-do the auto levelling, I have to extrude some filament first to make sure the auto-clean phase doesn’t retract the filament right out of the nozzle. If I don’t, I don’t get any filament coming out until until the 2nd layer (depending on part size).

I kinda regret not buying the TAZ5 instead, except for the price.

Lulzbot could have used a auto-levelling system that isn’t so easily prone to failure, like a microswitch instead of measuring resistance on a part that gets dirty all the time.

All the auto leveling systems have some tradeoffs. The microswitch ones get thrown off by oozed fillament coming out of the nozzle. The INductive ones don’t take the expansion or contraction of the nozzle into account, the Mini system is prone to nozzle uncleanlyness issues. I suspect someday the quickest auto leveling setup is going to be a combination of several sensors, perhaps a lidar and an inductive probe, but with the probe mount directly off the hotend so thermal expansion also moves it or something along those lines. An auto leveling system definitly makes 3d printing seem more accessable to people first starting out, and many people swear by them. I think once you get your bed dialed in though, you usually don’t need one.

I wondered about that… but after the autolevelling is done, the temperature of the nozzle is increased… I would imagine there would be further expansion taking place between both phases. Unless it’s done in software.

I’ve seen one system where the sensor is under the glass, and it’s activated by the pressure of the nozzle pressing down on the glass. To me, this would seem the best method out there right now.

That one works well if done correctly. It’s drawback is any debris on the bed, or on the nozzle (leftover Brim layers, etc.) throws the leveling off. Also some implementations of it had Piezo sensors that were prone to heat malfunction and the bed was cooking them after a few dozen cycles.

Current best practice for most other leveling systems is you get the nozzle to temperature, keep it at temperature for at least 2 minutes, and then level. The theory being that the expansion has occured by that point.

You come across very knowledgable, I like that.

If you were to design you’re own auto-levelling method, what method would you use?

I have an aluminum bed plate on my Taz and on my AO-10x, so in my particular case I’d probably go with an Inductive sensor, but on a thermally isolated metal mount bracket off the barrel of the extruder itself, so that when it expanded, the induction sensor also moved accordingly. Either that or the Pressure sensing Piezo bed that you mentioned. I tend to be horrible about keeping my nozzles clean though too, so I would have to take that into account.

I’m a fan of the non touch capacitive / inductive auto-leveling. Thermal expansion of the nozzle has little to do with these systems in the final setup. The sensor (aligned 2mm above nozzle) senses the aluminum or glass, then the firmware lowers the nozzle to the set height as set through the M212 setting.

It works wonderfully on my PSM, but PB have it pretty dialled in with their variant of Marlin… and I havent pursued on the TAZ, but others seem to have made good progress.

I second and third the fact that the auto-leveling just plain doesn’t work on the mini. I clean as others do and I’ve tried fiddling with the probe and wipe temp to no avail. It still just presses too hard on a random corner and ends up leaving no room for the filament to extrude when the nozzle is pressed up against the pei bed. Very annoying and a very big waste of time watching the failed startup of print after print. Wish there was a foolproof way of making this work, which is why I posed the question in the first place.

If I had a successful auto-level and the printer isn’t moving from it’s spot, I would rather tweak the z-height than constantly stop the startup sequence just because I know it pressed too hard on a corner and will ultimately fail the print.

If I knew it was going to be a shortcoming of the Mini I might have considered a different machine or spent the time to investigate the alternative methods implemented in other manufacturers or lulzbot models.


Have you considered contacting support? If your Mini’s autolevel is failing that miserably, there is something wrong with it. Mine works perfectly fine 95% of the time.

Have you taken any conductivity readings from the aluminum bed corners to the nozzle tip? Maybe you have some loose connections.

I’ll have to do that… because at this rate, auto-levelling on my mini actually works maybe 20% of the time.

That’s no good!!

I’m being generous here… 50/50 chance of passing, after I’ve manually cleaned the nozzle myself with a scotchbrite pad, and put in a new wiper pad. :smiley: If I don’t replace the wiper pad, that chance drops significantly. And the thing it is, the head looks totally clean even before it begins cleaning.

Anyways, I’ve fired an email off to support to see what they say.

For a $1350 printer, I’d expect it to work a bit more consistently.

The 3rd print out of my new Mini scratched up the PEI so I have a reminder now on the bottom of every subsequent print I make.

I’ll bet there is some loose connection or a broken wire or it is some strange environmental/filament issue. For my printing conditions (unheated garage, fairly humid), opaque PETG and ABS never fail the leveling – it’s so rare I can’t remember the last time it happened and I’m so confident it will work, I often don’t even watch the start with these plastics.

PLA however, especially black, is a completely different story (I’ve tried eSun and IC3D) – it fails a lot. I have to watch it like a hawk and manually clean before any print. I also had a lot of trouble with natural PETG (but zero problems with opaque white, though my sample size is too small to make any firm conclusions). I did have a problem with HIPS early on too, but then I discovered I was allergic to HIPS fumes and so haven’t really used it since my first two weeks with the printer. It might be fussy too.

Anyway, if you haven’t tried a variety of plastics, that might be worth a shot too. Based on my experience, opaque PETG is really easy to use even when the ambient temperature is in the low 40s, but isn’t as tactilely pleasant as ABS (but ABS hates a cold garage – needs summer ambient temps).

Checked the grounding on the aluminum heatbed, as well as the side screw on the hotend. Both were tight.

I took the opportunity to replace the extruder gears and clean the hobbed bolt while I was at it since the old gear had one spot that grinded badly and ‘popped’ as it passed by. The original large herringbone gear looked like it had some issues.

Ok, so I took Teddy’s advice and some other forum suggestion and ordered the blue 3M scotch-brite scour pad off Amazon. $8 for for two decent sized pads. Cut the pad on the short-end which happened to be around the same size as the grey stock Lulzbot wiping pad. Cut two strips and jammed push them in the wiping slot.

Link: http://amzn.com/B001PCYIBO

Using Simplify3D, I checked the startup sequence after talking to Lulzbot customer service (who were very helpful) and adjusted my probing temp to S180.

I’m using Verbatim PLA which as far as my tests concluded is superior PLA to all other brands. It really is that good for tolerance, color, and reliable prints.

Guess what?

Not a single overly flexed corner and perfect auto-leveling sequence!!! I’m going to knock on wood now, but I think cleaning the tip was crucial in getting the 5V leveling to work reliably on the corner washers. It’s makes a HUGE difference when you can have perfect conductivity on each corner and you can adjust your z-height so you get nearly zero elephant feet happening.

Here’s a picture of the blue scotch brite in place.


The biggest improvement to my auto-levelling woes has been to increase the wiping temp to 150 from 140 before probing.

Note: This is for eSun PLA

M109 S150                    ; set to cleaning temp and wait
M109 S150                    ; heat up rest of way
M109 S150                    ; set to probing temp