Mini first layer too big

Hi,

I have a new Mini that prints quite well, but exhibits a problem with the first layer. I am using the ‘ABS_medium_mini.ini’ profile in Cura to print a box, and finding the first layers make the box too wide (ie. the base is flared):


I’ve tried calibrating the filament size, altering “Initial layer thickness”, “Initial layer line width”, Bed/print temperature. Nothing touches it.

Any holes in the base are too small, as a result of the same problem.

Does anyone know what could cause this?

Thanks

John

When your mini taps the corner washers during the beginning of the print, do you see the washer / bed deflect? You should not see any movement in the bed or corner washer. If you do, your nozzle is probably dirty. I clean mine by bringing the hot end up to print temp and rubbing it with a folded cotton washcloth. Also, check that you do not have a bunch of plastic gunking up your wiper pad. If you do, flip it or replace it.

It looks like the first layer is being smashed out too much. That will happen if the bed measurement is being skewed by a dirty nozzle or washers or both. I essentially tells the printer the bed is lower that it actually is causing the first layer to be squished out.

One of the things I love most about my Mini is the near perfect first layer with no flare out. You should not be seeing that.

There is a setting for z-offset in the machine settings. Maybe try decreasing that a little bit, it should make your first layer a little taller.

Thanks for the suggestions. I will try cleaning the nozzle and putting in a new pad. It’s good to hear that this problem is not a normal thing.

Regarding Z offset, I had tried that based on advice from Lulzbot using the ‘M851’ command. But I could not find a value that fixed the problem, and adjusting it made the print extremely tough to remove from the bed. Actually, I’m finding that most changes (as mentioned in my first post) from the default .ini file seem to affect the adhesion to the point of being almost impossible to remove the print.

I run bone stock first layer thicknesses and offsets BTW.

Cleaned the nozzle, changed pad. But unfortunately, it made no difference. During leveling the nozzle just touches the discs. There is no deflection of the bed.

Turning down the initial base layer percentage to 100% (from 125%) worked for me for resolving the larger layer around the base.

I have had issues with circles printed on the first layer not being the dimension desired also. I have drilled out the holes on items I didn’t want to spend time reprinting to get perfect.

Can you flip the object so the holes are on the top? I’ve been printing with rafts lately to get a consistent surface finish (vs one side very smooth from being on the bed)… it might also help with the circles and/or large initial layers.

Hi Anonymous - where exactly is this “z-offset” in Cura? I’m looking at machine settings and there is nothing called z-offset… thanks!!

A new version of Cura has been released and in the new version you can configure the z-offset.

I have a similar issue. Cleaning makes no difference. Last time I checked the new version of cura is still ultimaker only unfortunately :frowning:

Here the V15:
https://www.lulzbot.com/cura

After a lot of email and two phone calls with Lulzbot, the issue is still not fixed. Lulzbot suggested the printer may be faulty, so I returned it and got a replacement. On testing it again (now using Lulzbot’s own 3mm ABS filament), I see the exact same problem. So with a brand new Mini, Lulzbot filament, stock settings from the ‘ABS_medium_mini.ini’, all the prints I have tried have the exact same problem: first layer too big.

nopick: when you say “I run bone stock first layer thicknesses and offsets”, what material are you using? What profile are you loading? You’re using Cura, right?

Does anyone have any further suggestions for what the problem might be?

Are some Mini’s just not capable of accurate first layers? Clearly, there are other people seeing the same problem.

I print PLA and ABS on the Mini. I use the Lulzbot Cura profiles for some things but I have also created S3D and Slic3r profiles based on the settings in Cura.

The bone stock settings I am referring to are the first layer thickness and Z offsets. In Cura, you can find the first layer thickness. For PLA I think it is something like 0.41 mm. In the other slicers, I do not change the Z offset so it should be printing the first layer at that specified thickness.

I have never had a flared first layer like that on the Mini.

If you post the stl and gcode of a part you are having problems with, preferably a small one, I will take a look at it and test print it.

The stock setting on that profile is to create an extra-high first layer, that is extra wide. See the attached screenshot. I would suggest going to the other extreme for a test. Set “initial layer thickness” to 0.25 mm (the normal layer height for that profile, see “Basic” tab), and set “initial layer line width” to 100%. That way, your first layer should be the same as all the others.


The reason for extra material on the first layer is to ensure good adhesion, but it also means the first layer is bigger in both height and width in the stock profile – in other words, you are seeing what would be expected. I’ve fiddled with those numbers (and had good results). The only time I need to bump up the line width above 100%, is when I’m dealing with a piece that has very little contact with the bed. Most of the time, I just use the normal layer height and 100-105% on the line width.

Yup, that’s the issues. I have made progress. Two things:

  • Z offset
  • Initial later line width

When Z-offset was set to -1.23, or thereabouts, it was having an obvious impact on the squish. If I then reduced the “Initial layer line width” from 125% to 100%, the problem went away!

I’m finding that modifying the Z-offset enough to prevent an oversize initial layer seems to cause the next few layers above to not be squished enough (part appears narrower for a few layers). I guess it’s a balancing act?

nopick: thanks for the offer to try my print. At this time, I think it won’t be necessary.

Thanks for all the comments, people!