RE: What is happening here?
Please take a clear closeup of the ends of the idler tension screws (not the head) as well as the position of the nozzle in the nextruder. It should look like the image on this page: Nozzle Insertion Check
- Bob Marley
RE:
I opened the project file you attached earlier. Some advice, I wouldn't print this in PLA and have it up against the chamber. PETG would be a better choice. Once you move on to other filaments that require a heated chamber you may find the parts warping.
- Bob Marley
RE: What is happening here?
Quick question while I have you. I'm currently printing a benchy with no problems. Why would the other print fail as soon as the first layer...but an entire benchy can print in 15 minutes with zero problems.
RE: What is happening here?
I will do this as soon as the benchy finishes
Please take a clear closeup of the ends of the idler tension screws (not the head) as well as the position of the nozzle in the nextruder. It should look like the image on this page: Nozzle Insertion Check
RE: What is happening here?
Ive never really had any luck printing in PETG. I either ended up with a bad rough print...and/or a damaged plate. I'm sure it was user error - but just kinda gave up on that kind. I will attempt again once I get the current problem resolved
I opened the project file you attached earlier. Some advice, I wouldn't print this in PLA and have it up against the chamber. PETG would be a better choice. Once you move on to other filaments that require a heated chamber you may find the parts warping.
RE: What is happening here?
Okay, I'll deeper dive into the extruder. I purchased it factory assembled so not quite sure how, but I'm sure I can find a yourtube video or an article on Prusa's site.
This is definitely either caused by: a clogged nozzle, debris in the extruder or perhaps the nozzle is not fully inserted into the nextruder. Either way something is blocking the filament's path through the end of the nozzle.
First, double check the heat block assembly is correctly inserted fully into the nextruder. Next, open the idler and look for debris. Perhaps a bit of plastic is blocking the entrance to the heat break tube. It could just be you have a bad nozzle. It's always important to have a spare nozzle and heat block on hand.
Would advise getting a spare (non-HF) nozzle and start with that. For example: Nozzles 3D Printer MK4
RE: What is happening here?
One last thought. I'm 100% convinced now that its a nozzle clog. When you are printing the PLA I assume you have the top vents opened? Try doing another cold pull and leave the door open when you print (you'll need to disable the door sensor in UI setup screen). Anyway, unclogging a HF nozzle is difficult at best.
- Bob Marley
RE: What is happening here?
Okay, two more Cold Pulls completed..and I took apart the extruder to see inside and also see how it works. No jams at all and no debris inside by the gear. I did see some lint (i think), large in first zoomed in photo...that is now gone.
Trying now again with door open. Also, yes, the vent on top is open for each one of these prints I've tried.
RE: What is happening here?
Quick question while I have you. I'm currently printing a benchy with no problems. Why would the other print fail as soon as the first layer...but an entire benchy can print in 15 minutes with zero problems.
The benchy’s first layer is tiny and in the center of the print bed. The geometry of the object being printed, in-fill and other factors control success rate. Large prints covering most of the print bed are always going to be the most problematic.
- Bob Marley
RE: What is happening here?
Ive never really had any luck printing in PETG. I either ended up with a bad rough print...and/or a damaged plate. I'm sure it was user error - but just kinda gave up on that kind. I will attempt again once I get the current problem resolved
I opened the project file you attached earlier. Some advice, I wouldn't print this in PLA and have it up against the chamber. PETG would be a better choice. Once you move on to other filaments that require a heated chamber you may find the parts warping.
I strongly recommend picking up the BIQU CryoGrip Pro Glacier build plate. You’ll have no problems with PETG (or any other filament) the exception being TPU which sticks too well to it. Also, PLA shouldn’t be used anywhere near a source of heat, or in a hot car, or outside. It warps very easily.
- Bob Marley
RE: What is happening here?
Okay, two more Cold Pulls completed..and I took apart the extruder to see inside and also see how it works. No jams at all and no debris inside by the gear. I did see some lint (i think), large in first zoomed in photo...that is now gone.
Trying now again with door open. Also, yes, the vent on top is open for each one of these prints I've tried.
Back out the idler tension screws until they are flush with the end of the idler nut.
- Bob Marley
RE: What is happening here?
If it happens again (the gaps in the first layer) I think one or more of the channels in your high flow nozzle is blocked. Also, check that the hot end is inserted fully into the nextruder heatsink and that the thumbscrews are not loose.
- Bob Marley
RE: What is happening here?
Okay, I have purchased multiple additional nozzles and an extra heat block assembly today for delivery tomorrow. Thanks for all the help, really. I’ll keep posting here the progresss.
If it happens again (the gaps in the first layer) I think one or more of the channels in your high flow nozzle is blocked. Also, check that the hot end is inserted fully into the nextruder heatsink and that the thumbscrews are not loose.
RE: What is happening here?
Okay, I have purchased multiple additional nozzles and an extra heat block assembly today for delivery tomorrow. Thanks for all the help, really. I’ll keep posting here the progresss.
If I may ask, what kind of nozzle did you pick up?
- Bob Marley
RE: What is happening here?
Yeah, no worries! 
Screenshot
Okay, I have purchased multiple additional nozzles and an extra heat block assembly today for delivery tomorrow. Thanks for all the help, really. I’ll keep posting here the progresss.
If I may ask, what kind of nozzle did you pick up?
RE: What is happening here?
OK, that should do. I don't have any experience with the ruby nozzles but having a nozzle on-hand that can handle abrasive material is always a good choice. Just remember to turn off High-Flow and turn on Hardened when you swap it out (I tend to forget myself sometimes).
- Bob Marley