First layer problems

[orso7 0]

I am using a Ultimaker 2 Extended for about a month now (at work)

Everything worked fine before the Christmas hollyday (sort of at least), unfortunately I have some first layer Problems now, Material does not stick quite well (especially things like the contour of screwholes). Even when I get it to stick there are some "dents" in the first layer (like it didn't stick on just 5 mm length of the infill lines) mostly when its part with a big groundplane.

I recalibrated the Printbed 2 times, cleaned it, ..... not getting better

also tried to slow down at Layer 0 by 50% (Tweak at Z) but unfortunately it doesn't slow down the first but the second layer???

Using:

PLA (210/60°) (Happens with different makers, Verbatim, Ultimaker, rec, ...)

0,6 mm Olsson Block Nozzle

0,1 mm layer thickness

0,4 mm first layer thickness

Frontdoor (piece of plexi with handle on top)

Another (minor) Problem that I have (was already persistent before), is that the first (or the first 3) layer is a bit wider than the rest by about 0,5mm, is there any trick to avoid this? I tried lowering the temp. of the bed, changed nothing, when I got to low the print didn't stick.

Hope someone can help me since I am already a bit desperate

[yellowshark 153]

OK,

Using the Cura advanced tab, set initial speed to 20 mm/s. It would be useful to know what speed you have been printing the 1st layer with?

Not sure what the 0.6mm nozzle impact is, if any, but most people use 0.3mm for the 1st layer, so it would be worth swapping to 0.3mm to see.

You say 60degrees, it would worth trying it a bit warmer, say 65, this does vary with printer/filament.

Are you using any adhesive? If not that will help - most use adhesive, not all. I use extra strength hair spray, many others use special glue stick or a sludge made from it.

Make sure you filament is flowing properly before starting your print. If you cannot manually feed it before starting (say 30mm) then if you are not using a brim then use a skirt, say minimum distance 30mm - the expert setting menu displays the settings for the skirt.

I assume you are saying the front door is closed. I do not think this will really have an impact, either way but I print PLA, including 1st layer with door open and the roof off.

Your elephant's feet - this will normally be caused by your nozzle being too close to the bed, i.e. not calibrated correctly. Lower the bed just slightly, say 0.05mm, and again if no effect. I use a more accurate process...

For the nozzle to bed distance I have a calibration test routine, using a standard cube. I have a z-offset in the start gcode routine which makes it easy to adjust the nozzle to bed distance automatically and accurately. I use a binary chop style process to adjust the distance. On my printer I need a z-offset to allow for the glass plate; I do not know how it works on the UM2 with a glass plate. If you do not need a z-offset then just set it to 0.0. So…

Having set the distance during levelling using the standard sheet of paper, and assuming my z-offset is 7.1mm I will print the test cube (1st layer or 2 only).

Then I add 0.04 to the offset and print again

If 7.14 gives a better result then I add another 0.04

If 7.18 gives a better result then I add another 0.04 etc etc

If 7.22 gives a worse result then I subtract 0.02.

If 7.20 gives a better result than7.18 I will try 7.21, meaning either 7.20 or 7.21 is the correct offset

Referring to the above, if I find that 7.15 is worse then I go the other way, setting the offset to 7.10 etc etc

[JohnFox 25]

The first layer being wider is called 'elephants foot'.

This is caused by the nozzle being a bit too close to the bed and the material is over extruded beyond the correct area. Lower the bed by about 1/4 of a turn on the screws and try again.

I have just been doing some tests of this problem and the main cause of 1st layer problems is the bed height. I use the Cura default of 0.3mm 1st layer thickness, I suspect with 0.4mm it is trying to extrude too much material.

Do you use PVA glue on the bed? I use a small amount of PritStick, then a tiny sponge with a few drops of water to spread it around, ( goes milky then dries). Never had PLA coming off the bed with this.