PLA vs PETG  

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bartbries
(@bartbries)
Active Member

Hello, 

I have my MK3S for several months now. In the beginning I tried printing some tests with PLA, which worked fine. Then I switched to PETG, to start printing the parts for the LACK enclosure (v1). All went well, and now I am printing all the time with PETG. Until yesterday... As I had still some rolls off PLA that I ordered together with my printer, I wanted to start using PLA too. The first part that I printed was perfect. I immediatly started a second (same item, I need 4). That ended up in the part becoming loose, and the spaghetti consequense. A second attemp had the same result. So I went back to PETG, after reslicing the object for the correct material, all went well with PETG. So now my question, why is PLA not working. Might it be with the enclosure? Is it better to remove it when printing PLA? I didn't have it when I started, and to me this is the only difference... Just for the info, I'm using a powder coated sheet. 

Any advice is more than welcome.

Posted : 26/02/2020 11:04 am
bobstro
(@bobstro)
Illustrious Member

PLA works better with a slightly lower (more negative) Live-Z asjustment. PLA is also much less sticky and really needs a clean PEI print surface to adhere. Otherwise, you get either a Blob of Doom or a Spaghetti Monster when the part pops loose mid-print.

Wash the PEI sheet under the kitchen sink with plain Dawn dish soap (or your local equivalent - Fairy in UK). Scrub it with a clean paper towel and dry it with another. Do NOT touch the print area.

You also need to clean the nozzle when swapping from high-temp materials (e.g. PETG) to low-temp materials (e.g. PLA) to avoid any leftover filament in the nozzle causing partial clogs. Read up on cold pulls and consider cleaning filament.

This post was modified 1 year ago by bobstro
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 26/02/2020 2:07 pm
ale.godoyr
(@ale-godoyr)
New Member

Can anyone advise me about using Creality PLA on my Prusa i3 MK3? Some experience with the quality of prints? 

Posted : 06/03/2020 3:35 pm
JoanTabb
(@joantabb)
Moderator

It's PLA,  if it's 1.75mm,   it should work as well as other 1.75mm PLA's...   and it happens to be badge engineered By Creality... 

where as Prusament is manufactured by Prusa...    

However Prusament works well on other printers too... 

It's a bit like cars... as long as you get the right sort of fuel, in a modest car, it will work,
Yes you can get 'Performance Fuel' and that will work ok in most cars...      
If you happen to have a Super Car you may need to use the higher octane fuels. but in most instances any petrol will do for a petrol car...  etc.    (engine oils are a slightly different matter...     Manufacturers do Specify which oils should be used...    I don't have enough knowledge to know if one is really better than another for a particular enging... but If I was running short of oil, and my brand was not available, I would use another brand, rather than run dry...   (obviously matching Synthetic/ semisynthetic as best I could... )

If Creality PLA is a good Price, Enjoy!

 

Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 06/03/2020 6:13 pm
ale.godoyr
(@ale-godoyr)
New Member

@joantabb

Thanks for the feedback 😀

Posted : 06/03/2020 7:14 pm
Pavel
(@pavel-16)
Eminent Member

bobstro did not finish the advice ... 

;>)

but even more important (or more specific), make sure to adjust the Z offset (Calibration, First Layer) . 
as an example, for PLA - my Z alignment is   -1.200mm

for PETG I have to change it to -1.000mm for the print to stick correctly. 

Posted : 08/03/2020 11:59 pm
Chocki
(@chocki)
Prominent Member

Some more advice if you are planning on regularly swapping filament and have a textured sheet. Get another smooth PEI sheet and keep this for PLA and keep the textured sheet for PETG only. This is not PRUSA advice. just observations by myself and reading what others have posted.

Also it means you can dial in your Live-z for each sheet per material so no need to apply offsets in Slicer or adjust Live-z between prints.

There is a thread by vintagepc where he is carrying out some testing on adhesion of filament to different sheets, so keep an eye on this.

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-general-discussion-announcements-and-releases/a-tale-of-two-sheets-discussion-thread/

 

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 09/03/2020 7:05 am
bartbries
(@bartbries)
Active Member

Hello, I have ordered yesterday the smooth sheet, and I will do like you say, Smooth for PLA, Powdered for PETG.

Which one should I use then for ASA. I'm thinking of making a lithophane, I wanted to do this with PETG, but Prusa is not providing white PETG, so I was considering the ASA. I am still a bit hesitant to do it with PLA...

Posted : 09/03/2020 7:11 am
Chocki
(@chocki)
Prominent Member

Never used ASA so cant help, but, again not knowing about lithophanes, does the outside surface need to be perfectly flat ? or does it work textured?.

Aside from this, I found the Textured sheet can be a little bit variable with printing thickness, not really a problem if your part has many layers, also getting a perfectly flat heated bed is challenging if not impossible with the textured sheet. I bought a FYSETC flat spring sheet with PEI stuck to it, and can get a really flat and even first layer with even light showing through which I cannot do with the textured sheet. I have replaced all my outside edge spacers with springs and carried out bed adjustment to get the flat first layer at printing temperature. This I can achieve with the flat sheet, but no amount of adjustment will get me a perfectly flat first layer with the PRUSA textured sheet. It's good enough for parts, but not anything where light needs to shine through.

You may have more luck than me, but before trying ASA, see if you can print an even first layer of PETG on the textured sheet, hold it up to the light and check you don't have the unevenness I suffer with. If you do, then it looks like flat sheet all the way.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 09/03/2020 8:44 am
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