How to Switch from PETG to to PLA without a clog?

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Vandal968
Posts: 215
Joined: Mon Jul 13, 2015 4:30 am

How to Switch from PETG to to PLA without a clog?

Post by Vandal968 » Sat Oct 05, 2019 8:07 pm

I can print PLA and then switch to PETG and everything is fine. However, every time I switch from PETG back to PLA, I get a massively clogged nozzle that needs to be torched clean within just a few prints. What is the best way to successfully transition a hotend from PETG back to PLA without clogging?

thanks,
c

airscapes
Posts: 365
Joined: Wed Jan 31, 2018 11:36 pm

Re: How to Switch from PETG to to PLA without a clog?

Post by airscapes » Sat Oct 05, 2019 10:58 pm

You need to by eSun cleaning filament. When you change filament type you run about 8-10" of this through your hot end a the same temperature as the previous filament. You need to do it slowly so it blends with everything in the nozzle, it is surprising how long it takes to get it flushed.
Once your cleaning filament is coming out clear of color from the previous filament, back out what is left (I cut a length that is about 10 inches and you will have about 3 inched you don't use.) Switch the temperature to the new filament temp and extrude about 2-3 feet of the new stuff. do it slowly and stop to let the filaments blend in the nozzle. You will be tempted to say that is enough but it is not. If you do not get every bit of the cleaner out your next print will not stick to the bed and will delaminate
That is the only caveat of using this stuff. If done with every change you will never get a clog. I print ABS /PLA /PETG /Nylone/ TPU never do I remove the nozzle or have a clog. The other thing you need is a brass brush to clean the outside of the nozzle after or before every print. Just bring it to temp and buff it like you are shining a shoe. Some times is pla is not flowing and twisting around as it comes out the nozzle, I will extrued and buff at the same time till the thread flows straight is the right size. Again you have to set the extrude speed slow.
Cleaning filament
https://www.amazon.com/eSUN-CLEANING-Fi ... NrPXRydWU=

Brass brush https://www.ebay.com/itm/Tire-Repair-Br ... 2749.l2649

That is all you need, the cleaning filament will last years, I have had my little roll for almost 2 years and have not put a dent in it yet..

Vandal968
Posts: 215
Joined: Mon Jul 13, 2015 4:30 am

Re: How to Switch from PETG to to PLA without a clog?

Post by Vandal968 » Tue Oct 08, 2019 1:47 am

I do have the eSun cleaning filament, but I've never had much luck with it. It usually feeds a little, then gets stuck and I end-up trying to mash it through the hot end manually. This is BEFORE a clog, normal printing filaments always feed fine, but the cleaner filament seems to feed like sh*t. Is there a trick to it? Also, when you say to feed it slowly, what feed rate do you recommend?

cheers,
c

airscapes
Posts: 365
Joined: Wed Jan 31, 2018 11:36 pm

Re: How to Switch from PETG to to PLA without a clog?

Post by airscapes » Tue Oct 08, 2019 4:01 am

Yes, sometimes you have to manually push it in as it is soft and undersized at times. I have feed rate in octoprint profile for manual extrusion set to 100mmMinute . I have the extrusion lenght set to 5mm so once it starts to come out the hot end, I click 3 or 4 time and push filament if need be, wait 30 seconds and repeat. It is tricky at first but once you get the hang of it really works well. Just switched from abs to nylon 910 without using it as I was going up from 235 to 255C but have to clean it to go back to abs. I think I stopped having issues with the feeding once I get my tension set correctly for TPU, it is a fine line to get ninjaflex to print well.. and had to go almost a complete turn tighter for nylon. Too tight and the cleaner get squished (techno term) and won't feed too loose and you are pushing.. But honestly, I have not had a clogged nozzle ever after starting to use it regularly. That include my .25 nozzle..

Vandal968
Posts: 215
Joined: Mon Jul 13, 2015 4:30 am

Re: How to Switch from PETG to to PLA without a clog?

Post by Vandal968 » Mon Nov 25, 2019 12:22 am

I wanted to circle back with my results once I had printed enough to know if Airscape's advice was really working for me or not.

Verdict: WORKS GREAT!

I've now switched back and forth twice and printed an entire spool of PLA without a clog or any issue whatsoever, previously I never made it more than one large print before a jam when switching in the Petg to PLA direction. Thank you so much, that cleaning filament had been giving me fits. Two observations that have made it work even better for me:

1. Before swapping filaments, I make sure that I used a colored filament first. Pretty much anything other than white or clear is ok, but darker is better because that way you can see when the filament is truly running clear with the cleaning filment so you know when to stop.

2. I don't like wasting filament, so instead of cutting off a 10" length, I mark a little sharpie mark 10" or so from the end so I can track how much I've fed thru. If you do it this way, mark the filament with a contrasting color. IE, don't use black sharpie if purging black filament because you won't know if you're still purging old crud, or if it's your sharpie color coming out of the nozzle.

Thanks again!

cheers,
c

airscapes
Posts: 365
Joined: Wed Jan 31, 2018 11:36 pm

Re: How to Switch from PETG to to PLA without a clog?

Post by airscapes » Thu Nov 28, 2019 1:23 am

Glad I could help! Just don't get too Scotch on the running of the next filament after the cleaner.. not sure why it takes soo long to get all of that out but like I said, any cleaner left in there and your print won't stick and can delaminate..

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