First Print...Nozzle Clogging?

[DLS3141]

So, I'm still battling with my Rostock MAX v1. On my first try, the nozzle clogged and in the process of disassembling it to clean it up, I broke the thermistor and cursed the power resistor heaters and the high temp RTV. So, after cleaning I rebuilt the hot end with a threaded thermistor and a cartridge heater. I also replaced Steve's Extruder with the EZ Struder.

I'm using Matter Control and have run the PID auto tune on the bed and the hot end, calibrated the heights per geneb 's manual...all good. When I messed around with extruding some ABS filament manually at 228C, it came out in a nice soft string...at 235C, it made a gooey glob on the nozzle. I measured the filament diameter and found it varied from 1.75mm to 1.73mm over an approx 2m length.

When I tried printing the fan shroud at 228C, the print started out just fine, the first few layers looked great, then they got a bit rougher...looking as though the nozzle were "sputtering", missing in spots, but not enough to stop extruding totally. After the part was about 1/4" tall though, the nozzle was not extruding at all and while the nozzle was being moved along the correct path, the extruder was not pushing filament through the nozzle, and I could hear the hub in the extruder "clicking" on the filament. I stopped the print, retracted the filament and then manually removed the filament from the bowden tube.

After removing the part, I tried printing it again at 235C and got the same sputtering, then nothing only sooner, within the first few layers.

Any suggestions?

[mvansomeren]

It's hard to tell from what you wrote but did you break the thermistor and then powered up the hotend? If so, it's likely that it overheated and damaged the PTFE tube inside. That could account for the clogging. I've never had ABS clog the nozzle (I'm assuming you're using ABS based on the temp you posted).

[DLS3141]

No, the thermistor is definitely not broken. I did break the original thermistor when I disassembled the original build of the hot end. I replaced it with a new, threaded thermistor. I'll check the PTFE tube, but The problem is similar to what happened the first time and I saw no damage to the PTFE then.

Yes, I'm printing ABS, or trying to anyway.

[mvansomeren]

Have you tried a different brand of filament? Maybe you have a bad roll?

[DLS3141]

That is a possibility. I got the roll shortly after I built the machine. It's been sitting around for over a year, sealed in plastic. I think I'm going to make some more measurements tonight over a longer section to see if it is dimensionally out. Otherwise I don't know how to evaluate the filament aside from trying it.

[mvansomeren]

The only reason I bring it up is I've read threads about some filament that had impurities that caused clogged nozzles. If I remember correctly it was some no-name brand purchased through ebay. Not saying that is your issue but something to consider.

[BenTheRighteous]

Did you replace your original thermistor with one of the exact same type? If not, you need to update a value in the firmware so it knows how to read the new one properly.

[DLS3141]

Did you replace your original thermistor with one of the exact same type? If not, you need to update a value in the firmware so it knows how to read the new one properly.

Yes, I made sure to buy the exact thermistor p/n as spec'd in the original kit. I haven't developed an independent calibration yet.

[BenTheRighteous]

How sure are you that what you have is actually ABS? Have you burn tested it? I wonder if you actually have a roll of PLA that was mislabeled as ABS. It's happened before.

[DLS3141]

I haven't burn tested it yet. When it melted, it sure smelled like ABS though. I'll burn some when I get home.

[DanHall]

You may also try drying your filament. Search and you will find the correct oven temps and times.

If you are getting steam in the hot end it could mess with the pressure enough to have the extruder chew a notch in the filament to the point it no longer has anything to grab ahold of in there.

I have had bad rolls of ABS filament that have clogged nozzles creating similar issues though. For me those seem to just stop extruding all at once rather than sputtering along for a while. They can be a pain to clean.

[DLS3141]

Hmmm.

I'll try oven drying the filament. See if that helps.

Of course I need to clean up the nozzle first. Luckily when I rebuilt it, I did so on the assumption that I'd be doing it again and made improvements to allow for easier disassembly and reassembly.

[DLS3141]

Success!

My problem is that I might be an idiot. The filament I have been using is PLA, not ABS.

In my defense, the label on the spool that said "PLA" is small and was oriented facing the wall where it was not visible.

Once I cleaned out the nozzle and set the temps correctly, things went so much better. Not perfect, but much better. The bridging was a mess. I don't know if I was still printing a bit too hot, I need a layer fan or both or if the solution lies elsewhere.

Anyway, thanks to all who replied.

[Mac The Knife]

for pla, you need a layer fan.

[DLS3141]

for pla, you need a layer fan.

Thanks, I know that after reading up on it. The first thing I printed was the PEEK fan shroud, the second was the shroud for the layer fan. Now I just have to connect them. I can connect the PEEK fan to the same place on the Rambo board as the heater, but I'm not sure which connection Matter Control uses for the layer fan.

[Mac The Knife]

The V1 manual doesn't seem to cover the layer fan, but in the V2, you would connect the layer fan to fan 0

[stonewater]

you cant use PLA for the peek fan shroud..... gotta use ABS... ask me how I know....

Tom C

[DLS3141]

The messy gooey way, I'd guess. In that case, I guess I need to beg/borrow/steal enough ABS to print one then. I don't really want to print with ABS because of the smell...

you cant use PLA for the peek fan shroud..... gotta use ABS... ask me how I know....

Tom C