Top layer just not right  

The three commonest things that cause changes to creep in are:

Insufficient general maintenance, especially cleaning and lubrication.

Damp filament: check some of the threads here about drying.

Wear, usually nozzle wear if abrasive filaments have been used.

It doesn't look like under extrusion (picture isn't quite clear) but if drying doesn't help try a cold pull in case there's a partial clog.

Cheerio,

RE: Top layer just not right

Thank you Diem.

I actually just added this question in the Hardware, Software, Firmware section as I felt it was more appropriate there so I apologies for the duplication.

I don't think it's the filament as it happens with different brand new rolls. 

I've tried cold-pulling but it hasn't made much difference. 

On maintenance, I've cleaned the gears but have not lubricated them ... is this needed?

Are there other general maintenance issues that could be causing this? 

What I don't understand is how the first layer is so perfect but the top layer just isn't. 

Maybe this image is a little clearer ... 

This is the first layer although I realise you can't really see anything in this image! But it's very smooth which is my point!! 

RE: Top layer just not right

There is a big functional difference in the first layer of any print and its top layer.  the first layer sees filament squished against the heated bed, so it should end up being perfectly smooth (anything else is a sign that you have a problem somewhere - usually Z height).  the top layer doesn't have that.

I've had problems with the top layer when I was getting slight over-extrusion/oozing - caused by a worn or inaccurate nozzle (cheap 0.4mm nozzles from China turned out to be wildly inaccurate, for example).

You could also experiment with the ironing feature in the slicer?

I don't think it's the filament as it happens with different brand new rolls.

Evsn new rolls are sometimes damp, drying is never a mistake.

Are there other general maintenance issues that could be causing this?

Clean and lubriate the smooth rods.

What I don't understand is how the first layer is so perfect but the top layer just isn't.

Maybe this image is a little clearer

Tbh it looks OK to me, fine for anything I print.  If you want better try flipping the part and printing face-down.

Or, as @richard-d suggests you could try ironing but I've never seen the point of it, sandpaper and paint is usually better.

Cheerio,

RE: Top layer just not right

 

There is a big functional difference in the first layer of any print and its top layer.  the first layer sees filament squished against the heated bed, so it should end up being perfectly smooth (anything else is a sign that you have a problem somewhere - usually Z height).  the top layer doesn't have that.

Thanks @Richard-d.  I had read elsewhere that most print finish problems are actually caused by first layer problems, which is why I was relating the two, but sounds like they are unconnected in this case. 

I've had problems with the top layer when I was getting slight over-extrusion/oozing - caused by a worn or inaccurate nozzle (cheap 0.4mm nozzles from China turned out to be wildly inaccurate, for example).

I'm using a Prusa nozzle but maybe I should change it as it's been working a while. Good one. Thank you.

You could also experiment with the ironing feature in the slicer?

Has this been implemented in Prusa slicer now? (no need to answer this ... I will check 🙂 ) 

Clean and lubriate the smooth rods.

Thank you @Diem ... I really appreciate your replies (in this and my other threads).  I'll do this too. 

Tbh it looks OK to me, fine for anything I print. 

That's good to hear! I guess the reason its bugging me is because it has significantly deteriorated recently and I can't figure out why!