Inconsistencies  

Re: Inconsistencies

AFAIK, nozzle orifices get bigger with wear rather than smaller. It looks to me (not claiming expertise) like a clog/constriction somewhere (PTFE tube?) if that's indeed at issue.

I think I'd try cleaning the nozzle first. If that doesn't help, I'd check out the entire filament path from where it enters the extruder to where it exits.

I might also check the filament's diameter consistency.

Re: Inconsistencies

Okay, Thanks. I just checked for consistency and the print came out almost the same, maybe it's the surface too?
So the sheet was flipped over and cleaned. I got a good line but this is the result below.
I do have a PTFE tube, a nozzle, cleaner filament and some filament coming tomorrow.

Re: Inconsistencies

Easy enough, stop, look at where it is failing. It is failing in the longest infill lines in the center. What is special about the longest infill lines in the center? They are long and therefore due to how acceleration subtracts from the feed rate the longest lines are reaching the fastest speeds, where the shorter lines are acceleration rate limited. Simply put, you are pushing the max feed rate for first layer and so sure, you extrude too fast, the extruder cannot keep up, maybe it skips a step pushing the filament and you get pressure loss. As it slows down at the ends of the line it can produce the nozzle pressure and no error and the extrusion looks fine.

Simply lower your feed rate, and really if it's choking on the middle of first layer- think about what happens on far faster middle layers of a print.

Re: Inconsistencies

That's the thing. This is simply a gcode file that slowly prints for you to get your Live Z correct from here: https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/life-adjust-z-my-way-t2981.html#p97208 I haven't sped up or slowed down anything. It was working fine a week ago, including the first layer right up to a full Terminator 800 head. Now it appears to have problems. I'm just trying to figure out what.

Re: Inconsistencies

My MK3 printer has begun to ooze a bit. The line of filament that is printed at the bottom of the print bed is incomplete, and there's some stringing going on. The oozed filament looks twisted too. Printing the calibration surface I can see some areas of inconsistencies in the same places where the square is thin enough to split [Picture uploaded]. Nothing has changed with my printer in the week or so since it was completed. Perhaps this is two problems?

Does this mean it's time to replace the nozzle?

You are not mentioning what type of filament you use, but when I have more than normal ooze and the filament starts to curl up, it is because there is moisture in the filament and I need to dry it.
It is easy to test - if there is a cracking noise when slowly extruding it is vapor escaping the nozzle.
Most filaments absorb water when exposed to the surrounding air.

Re: Inconsistencies

Does this mean it's time to replace the nozzle?

You never mentioned how old the nozzle is. If it's 150+ hours old then it won't hurt to replace it. IMO it's a waste of time and energy to attempt to clean a standard brass nozzle, when they can be bought so cheaply.

Re: Inconsistencies

The Nozzle has been used for under 100 hours with silver PLA. I'm getting filament coming out in nooses, in fact I just moved the extruder setting and got a nice big silver noose. I get a chunk of filament here and there with some string and even the frame around my print has string coming off of it, it's wrecking the print.

Re: Inconsistencies

So last night I managed to get the live z adjust perfect again, with exactly the same setting as before. Now I'm trying pearl blue filament and the print looks rubbish. I just checked the printer and there was a ball of molten filament. I guess I'll change the nozzle and see.