Unresolved PETG warping on large parts.

Alright, so i took off at noon yesterday to get everything up and running and this large print i have started. I ran the PID Tune and changed my extruder temp to fall from 245 to 235 in 2-3 degree increments per layer and i think that fixed my issues with it dropping straight from 245-235 and not being able to stop itself. I adjusted my Z offset down to -.79, had the print running for about 4 hours before my first extruder jam. Luckily i caught it right away and just fixed it and kept the print going. I turned up my heat a couple degrees and just hoped for the best. Well i woke up this morning at 4:15 to go to work and it's printing air again.. I hate to pull parts off the printer that's been running great for me but i need to get this print finished. I cannot figure out why this one printer keeps jamming on me. I have an "upgraded" hobbed bolt on the printer that's been reliable so maybe i will switch that and the hotend out and try it again. Would the E3D v6 hotend be a worthwhile upgrade over the stock hex end i have? Robo support mentioned they were working on a new hotend, has anything came of that?

So pretty basic stuff, other than now that i got my sheet of PEI installed i put glue stick on top of that. Everything went fine until my print got about 1/4" tall and the back side warped up on me. The front stayed down just fine though. This PEI is .030" thick so maybe i need to turn up my bed heater higher than 80. You can tell it doesn't transfer the heat with it being so thick. I might try to just print straight on PEI and hope it releases when it's done. So frustrating but i feel like i'm pretty close. I'll try printing with an even bigger raft or maybe try that wolfbite on top of the PEI instead.

Thanks for all the help guys, i'd be lost! Gonna leave at 11 today to go home and work on it. I have another decent sized print to do this weekend so hopefully i can get them both done.

 

i'll have to order some. For some reason i never ordered spares.. I wish i could just overnight a new hotend assembly but Amazon says it would be Monday and i'm not sure where else to get one. Cost not being an issue, what would be the best one that would bolt right up stock?

I actually have the nozzle from my old hotend that was leaking, i could swap that out first. Only thing that sucks is it took 4 hours for the first jam. So replacing the nozzle i could still have issues and i'd waste another half spool of material in the process. I think a whole new hotend would cause me the least downtime although it's probably overkill.

 

My first thought when this printer was clogging was possibly bad filament. But my other printer has done multiple 24+ hour prints with the same filament so it has to be something else.

Gotcha, yeah i wasn't sure what the advantage of an E3D would be or if it would be worth it. i'll inspect mine and see if there's anything i can see out of the ordinary.

It seems to be printing great and nothing is really sticking to the nozzle to cause it to jam up.

 

. I have a PEI sheet on my bed and print PETG with nozzle and bed . Never have any issues. Same temps with glue stick on my second ROBO which has only glass bed, and no issues with PETG. Printing with it as I post

 

So you print on the PEI sheet with glue stick? I just tightened up my extra hotend and installed it on the printer and cleaned all the glue stick off of it and i'm going to try to just print directly on the PEI with a large 2 layer raft. Hopefully this hotend doesn't leak or jam.

BTW i broke that hotend that was jamming up so guess i'm ordering a new hotend anyways now. Yeah i'm an idiot...

 

What new heaters did you order up and where did you get them? Are they giving better results?

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Well just an update. Finished up a 30+ hour print last night with no problems after i switched out hotends! Had issues printing with glue stick on the PETG so i went and bought pure Acetone to clean the PEI off. Printed directly on the PEI and it released perfectly when i got home this morning after it was cooled off. I've never read of anyone printing directly on cleaned PEI but it worked awesome for me with a bed temp of 80.

The only thing i'd like to try to fix now is my new heater taking 10-15 minutes to heat up to 80. Sometimes it will just sit at 78 and i have to change my process to start at 78 instead of 80. I'm going to try to run the PID Tune for the bed and see if that helps but it might just be because it's an under powered for what i'm trying to do. As long as it still works and is reliable though i probably won't worry about it. Might have to upgrade to 24v someday.

 

Well.. spoke too soon. I brought in 2 large parts i printed for work today and am realizing that they both measure big on the Y axis. 12.4" saw fixture measures 12.6". So now both of these parts are scrap. The X and Z dimensions are correct but how do i go about fixing the Y axis. Obviously it's because i've extended the bed on Y but i'm lost as to why it's so far off. This really sucks...

 

All i changed was the auto level spots in the firmware to probe the bigger bed. I figured i wouldn't need to change anything else so i'm lost as to why it's doing this.

 

It's not like it's slipping or anything is loose because the prints come out looking good with no mismatch. I assumed they were good to go.

I guess i will check the Y axis steps and maybe reflash the firmware and try some test prints. What a bummer.

 

I printed a few things just didn't pay close enough attention i guess. I assumed that calibration wouldn't be affected by just changing the size of the bed. I can save the larger fixture it's just going to take some machining time. As for the smaller one i'm just going to reprint it on my other machine that i know is calibrated while i mess with the other machine.

 

yea i got caught up with trying to solve my warping problem and my extruder jamming up. Didn't even think much about calibration. I have longer Y axis rods, longer plate, and a longer drive belt. I guess it's possible the drive belt is different than what came stock but i was fairly certain what i ordered was the same. Surely over extruding wouldn't cause that much of a change, right?