Lower layers are bumpy and rough

[fingerpuk 0]

Hello.

I can upload a photo if needs be but it's simple to explain. After the brim is printed and the model layers start, the first few layers are bumpy and messy, and then it slowly starts to get better. Any thoughts?

Cheers.

 

[IRobertI 520]

Could be a couple of things:

- Your bed is a bit too close to the nozzle. During the brim pressure is building up but not escaping, when it's doing the first layer pressure is building up as well but eventually it manages to break through and a blob of plastic is the result. Does it look like there's a really really thin layer of plastic for a while and then suddenly it gets bumpy - rinse repeat?

- Your filament may be thicker than the default 2.85mm that is set in the firmware. Measure your filament diameter in several places. Also measure at 90 degree angles in case it is oval. See if it's significantly higher than 2.85mm. If so, change that in the material settings on the printer.

- Could also be that the plastic isn't adhering well to the bed. If you're printing without glue, make sure the bed is very clean, fingerprints will stop the plastic from sticking. If you're using glue, make sure it's a nice and thin layer. Put on a thin layer of glue and then use a wet piece of cloth to spread it around and then let it dry. You'll barely be able to see the glue.

 

[fingerpuk 0]

I'll give all that a try, thanks.

Checking the filament I get 2.86 - 2.95 at various points. It's an ellipse though in cross section, so not a 2.95 diameter circle.

I do use glue, it's very thin. So I'll re-level the bed. When it says to move the bed closer to the nozzle until you feel th paper catch a bit, how much should it catch? I can just about feel it catching.

When this print finishes I'll upload some close up shots so you can se the brim. If I can get it off the bed, these things stick really well.

 

[gr5 2,172]

Really "bumpy" can describe at least 3 different problems so a picture would be best. It's likely either too close or too far levelling issue.

 

I can just about feel it catching.

 

Perfect. Levelling is very critical but once you get it you shouldn't have to touch it for weeks.

If you are too close then the extruder buildes up pressure and the feeder skips and you get under (no) extrusion for a few seconds and that looks kind of bumpy. If you are too far the lines that you lay down initially are wavy and not properly squared off and it looks like the printer is drunk. And it doesn't stick well.

And there are other possible issues.

 

[mnis 11]

During direct printing on glass without adhesive help you see it more clearly. If you have leveled very close to the glass, then the first layers, look almost like a cloudy sky. Particularly clear you can see it if you use colored material with transparency. I think it also has to do with the fact that a glass surface is never totally flat. So you can see the topography of the glass. Or is that wrong?

Markus

[fingerpuk 0]

I think my levelling is good then, as I'm getting squashed but clearly defined layers. I'll see war happens today, latest print has been running for 12 hours and has another 8 to go. Although that time is changing regularly.

 

[gr5 2,172]

the first few layers are bumpy and messy,

 

Your starting to annoy me that you still can't post a picture. It just occurred to me maybe you meant the *sides* of the layers and not the bottom surface. That is usually caused by build plate too hot - 75C is too hot. 70C is okay. 60C probably better depending.