First Layer Issue

[JustMatt]

Hello Everyone,

I've got a cheap I3 knockoff from Gearbest that has been working well for the past year or so. Recently, it began making a clicking noise when laying down the first layer. When looking at what was deposited on the print bed, you can see there is a "miss" that corresponds to the times that it's clicking. At first, it wasn't much of a big deal, because I typically print on a raft and that covers up most of the flaws. However, now it has gotten to the point that it is almost completely missing the first layer and just clicking away while the head and bed move around doing their thing. Measuring some of the failed first layers that I've bailed on, it is coming out at ~.2mm thick from a .4mm nozzle. Does this mean that the nozzle is starting to get clogged and that the extra pressure of having to squeeze the first layer is too much for the extruder to advance more filament? Also, if I heat up the extruder and advance the filament manually in the home position, the resulting extruded filament is only coming out around .3mm or so. Is this another indication of a partially stuck nozzle, or will the filament get drawn thinner by gravity as it comes out of the nozzle if you just let it go into space?

For reference, here's a picture from when it wasn't so bad:
0609171528_HDR.jpg

Thank you very much in advance for any suggestions you might have.

Matt

[curious aardvark]

sounds like clogged nozzle.

[Marm]

sounds like clogged nozzle.

Yes, but no. (EDIT: Ok, finally looking at the pic, probably yes, but I'll leave the rest for future people searching for clicking noise).

When my bed gets way out of whack, sometimes the tip of the head is too close to the bed. The filament can't get out, and the clicking noise occurs.

So fix both, as they are part of routine maintenance anyways. Clean and unclog the nozzle, and level/calibrate your bed.

[JustMatt]

Thank you very much for the advice. I was very lucky in that I ended up getting the kit I bought set up and running on the first shot, so I didn't end up learning very much about the printer. Instead of cleaning the nozzle, I decided to just replace it. I thought this would be easier, but it looks like I was wrong. I thought everything was good after I replaced the nozzle, but after testing it out I saw plastic oozing out of the top and bottom of the heat block. I tried taking off the hot end, but just got the wires tangled. I removed the extruder assembly from the x-axis and was able to get the hot end off. Next, I tried to get the teflon lined barrel off the heat block, but ended up shearing it in half. At that point, I didn't care about preserving the threads anymore, and tried to just twist the rest of the barrel out. Naturally, that ended up shattering, leaving me with a chunk of barrel still in the heat block. I tried drilling out the remainder of the barrel and running a tap through it to clean out the rest, but I think I may have just destroyed the remaining good threads in the heat block. After all this, I'm left with a few questions.

Just how close should the nozzle be to the bed? I set up the printer originally with a piece of paper as a feeler gauge. Is that too close? I do have extremely poor environmental control around my printer, so that may be a factor.
Was plastic coming out of the top and bottom of the heat block because the nozzle and barrel weren't pressed firmly against each other?
The replacement nozzles I got have the same thread size, but use a M6 wrench, the original was a M8 (not sure about the exact size off hand). Would the difference in mass make a performance difference?
If I need a new heat block, would there be a performance difference between an aluminum one or a steel one?

This ended up longer than I anticipated, sorry for the wall of text. Thanks in advance for any information or suggestions.

Matt

[Marm]

If your tire is low on air, you don't go buy new tires. You add air, and then look for and fix a leak if it's still low. Only when all else fails do you get new tires.

Occam's razor.