Welcome to the SeeMeCNC Community

So I have finally gotten my RmaxV2 up and running. I was able to get the Peek and Layer fans to print with decent quality in ABS right out of the box. I was very pleased with everything except I have an Onyx V3 with the dreaded "can't reach 90 degrees" issue, in spite of the 725W power supply and 14AWG wiring I used for the build anticipating a problem. I see someone received a V5 Onyx already and it has the holes drilled off kilter, so I will stick to PLA for now. (Note: I used a light bulb to heat the bed to 90 for the first ABS layers and it got there after 40 minutes and was able to print without issue. Even after I removed the bulb just as the extruder lowered!)

One problem I seem to have is the PLA seems to sputter and pop coming out of the extruder and if I just extrude manually, I can see that there's a very narrow temperature band where the PLA extrudes nice and smooth with no spitting. If the temp gets a few degrees higher, the PLA will pop and snap and make puffs of smoke out the extruder, and the thread extruding will be coarse and not smooth or will have a gap where the pop took place as it came out. I had to lower the defaults to avoid this coarse looking extrusion issue. Now, If I lower the temperature too much, then I get adhesion problems where prints pop off the bed.

Now the new problem is it looks like the act of printing is dumping heat out of the nozzle (it leaves with the PLA that extrudes) so the PLA itself acts like a liquid coolant and it causes the extruder temperature to fall 10-15 degrees depending on what the flow rate is. I do the PID tune several times and it works awesome, but there's no filament extruding while the tune is going on, so I think the PID is not calibrated under the real world conditions and it lags behind the temperature of the hot end.

Anyone have any advice? Is this uncharted territory?

Sputtering and popping, from what I've seen in these forums over a long period of time is primarily due to humidity. I'm not sure of your temps - and perhaps your environment is a bit cold.

Some have stuck their filament in the oven for a while at low temps and others have come up with interesting maker solutions like putting the filament through a heater after it comes off the spool.

The popping and smoke (it's actually steam) aware a sign of wet, possibly bad filament.
A lot of cheap PLA is crap, and unless it's changed I wouldn't recommend the SeeMeCNC PLA either.

You shouldn't see a significant drop in temperature when you are printing, are you sure it's the PLA running through the nozzle and not the layer fan turning on. My guess is that latter, and you have to do the PID tuning with the fan on to account for it.
I personally recommend turning on the layer fan before you start the print with PLA, and just run it for the entire print.

FWIW I commonly print ABS with the bed at 80C, more power won't help with the Onyx, you need more voltage, or a lower resistance heated bed.

JohnStack wrote:Sputtering and popping, from what I've seen in these forums over a long period of time is primarily due to humidity. I'm not sure of your temps - and perhaps your environment is a bit cold.

Some have stuck their filament in the oven for a while at low temps and others have come up with interesting maker solutions like putting the filament through a heater after it comes off the spool.

Thanks for the tips!

I didn't have the popping when I printed the fan shrouds in ABS, but I then switched to PLA and it did it, but for some reason it went away at lower temperature. I was thinking that perhaps the heat was causing some chemical in the plastic filament to outgas or something and made bubbles that were popping out of the extruder. I guess water vapor is pretty much the same thing. I just figured I had a brand new roll of PLA that was sealed in a bag with a big dessicant pack that there would not be a humidity issue.

It has been humid where I live the past few days, so I suppose it is possible that this has affected the filament.

Would it help to store the filament in a freezer or something, to keep moisture out?

Polygonhell wrote:The popping and smoke (it's actually steam) aware a sign of wet, possibly bad filament.
A lot of cheap PLA is crap, and unless it's changed I wouldn't recommend the SeeMeCNC PLA either.

You shouldn't see a significant drop in temperature when you are printing, are you sure it's the PLA running through the nozzle and not the layer fan turning on. My guess is that latter, and you have to do the PID tuning with the fan on to account for it.
I personally recommend turning on the layer fan before you start the print with PLA, and just run it for the entire print.

FWIW I commonly print ABS with the bed at 80C, more power won't help with the Onyx, you need more voltage, or a lower resistance heated bed.

Okay, thanks for the info. I may have been thinking too hard about what was going on. It might be as simple as a goof made in the PID autotune. Come to think of it, does it matter if the room temperature fluctuates? I installed the fans and did the final tune late one night and it got hot out the next day, so I had the A/C on. Either that had an effect, or I somehow made an error in the calculation or input.

Here's a thought... where should the nozzle be located in relation to the bed when doing the PID tune? Would being close to the bed cause the layer fan to cool the nozzle a lot more due to the air deflecting off the bed and onto the nozzle? That's something else that may be happening. I did my autotune with the nozzle off the bed about an inch.