The bane of auto-levelling

I notice that after a print or two, I have to heat up the extruder manually, and scrub the nozzle with a cloth to clean what the scrubber pad isn’t removing. If I don’t, when it goes to touch the corner washers, it presses down too hard and bends the platform on one or more corners.

Since it’s working on conductivity from what I read, any bit of plastic on the nozzle interferes with it getting an accurate reading and then it presses too hard on the PEI on the first few layers.

Has anyone come up with an alternate method of cleaning the nozzle? This happens even after a 2nd print on a brand new scrubber pad.

I’m only using eSun PLA at this point… perhaps its just an issue with the filament I’m using? I’ve seen it happen on some youtube videos as well.

The pads five acetone for cleaning abs off. You might see if there is something that eats pla that could be applied instead.

I’m actually surprised this is happening already. I’ve had the printer for 2 weeks, and printed a total of 8 objects on it. I’ve had to flip the pad over once already. The corner washes look pristine, so I’m inclined to believe its the nozzle that’s causing the higher electrical resistance.

I’m sort of surprised that they never used a microswitch instead to determine bed height.

The one major advantage to using the nozzle to set height is that the metal nozzle is variable in length, because metal expands. With the nozzle setting the height it is theoretically more accurate.

I can see the advantages of that route. The downside of course is anything that impedes it making proper electrical contact at the right height skews the leveling data.

Yeah. I think in the next few years we are going to start seeing more hybrid multi approach auto leveling systems with more than one sensor type for compensation for that type of event.

I’ve been printing about 80% eSun ABS, 19% eSun PLA, and 1% eSun PETG.

With PLA I have to frequently clean the nozzle manually and I always watch the leveling process very carefully as well as the first layer. PLA really gums up the nozzle and then it sticks to itself like epoxy. It also seems that every few prints, it won’t get started and I have to stop the print, heat it up, manually push through some filament and hit the extrude button a few times, then retry. I always carefully watch leveling and first layer when I’m using PLA.

PETG is like PLA but even worse.

With ABS, about 90% of the time I press print and just walk away without any further observation. The wiping cleans the nozzle just fine with as near to total reliability as is probably possible, and ABS doesn’t seem so gummy so it doesn’t smear itself all over the nozzle like the other plastics I’ve been using – I rarely have to do a manual cleaning. It always sticks to the print bed and it always starts flowing. I love ABS (I do have a vent hood over the printer).

Are you sure the issue is a dirty nozzle? On mine the wire on the hot-end was lose, causing the same bed levelling failure intermittently.

I also blamed it on a dirty nozzle because it seems that after lots of scrubbing it would work again – which was just because all the movement involved in cleaning caused the electrical contact to improve for a short time.

Try adjusting your wipe and probe temp up a couple degrees. I have noticed different plastics are a little sticky at the stock temps.

I print PLA and ABS daily on my Mini. A failed auto level sequence is rarely a problem.

I will give that a try, thanks!

A failed auto level sequence is rarely a problem.

Except for gouges in the PEI. :wink:

Thankfully, I have stopped it before any gouges happened!

The golden rule of printing… Always. Watch. The. First. Layer.

That has saved me many headaches.

I have replaced the felt pad, with a teflon-safe scrubbing pad that has been cut down to the same size and height.

Works a treat, doesn’t melt or stick to the brass nozzle, and the nozzle comes out SHINY clean after each wipe cycle.