How fast do I print the PETG?
Hi guys! So I finished building my mini and I have printed the logo, the frog, and Benchy. Those all came out great with the PLA that came with the machine. When I purchased filament for the machine, in my ignorance, I didn't realize that PETG was a different thing.
So now that I have 3 successful test prints under my belt, I wanted to download something off of Thingeverse and print it like I knew what I was doing.
When I run the first layer calibration, it seems as if it is moving too fast. I get waves (very slightly) off of the bed. But if I lower the nozzle further, it binds up when it gets to the square.
On top of that, when I try to print the file I converted in slicer, the print won't stick. It sticks during the test even though there are slight waves. But the first lay down doesn't stay in place and when it tries to start printing the stuff inside, it doesn't stick.
I was thinking the axis speed was too high. Any suggestions?
Which sheet?
Are you using the smooth steel sheet for your PETG print? If so, you might have problems with adhesion… There are ways to do it (which I’m sure the more experienced people on this forum will be able to advise on), but, generally, you’ll have better results with the textured sheet when printing with PETG.
Hmmm
I am using the factory smooth sheet. hmmmmm Maybe I should order a textured one. Thanks!
PETG
Are you using the smooth steel sheet for your PETG print? If so, you might have problems with adhesion… There are ways to do it (which I’m sure the more experienced people on this forum will be able to advise on), but, generally, you’ll have better results with the textured sheet when printing with PETG.
That is not true. You can print PETG with either sheet. I have been doing it for 2 years. You just have to adjust your live Z to get the correct adhesion.
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Chuck H
3D Printer Review Blog
sheet
I didn't order a sheet because in the manual, it says it can print PETG on either one just fine.
I am quite frustrated. Now I am trying to print something on PLA and I am having similar issues. I am cleaning the sheet for the PLA with a Alcohol prep pad and the first layer calibration seems to be OK. I have adjusted my live Z from anywhere between -300 and -760. It worked great for the benchy, the frog, and the Prusa logo at 760 but now PLA and PETG will not stick to the bed.
I have heard some guys use tape, glue or even hairspray. Any suggestions?
speed
I even have adjusted the speed in Slicer and on the machine. The machine's default seems to be 100. Does that mean 100mm/s? That seems a bit fast. Although I had not touched the speed for the benchy or any of the other preloaded test prints.
The Riddle of Adhesion
I'm going to post a full ifno dump on this. Apologies to anybody who's seen it already, but this is good foundation info for anybody getting started with the PEI sheets...
2.3.1. Understanding the PEI sheet and adhesion
The first thing to understand is that PEI is very different than most other print surfaces. Do some searching on the internet and you’ll find hundreds of articles on using glue stick, hair spray, glass sheets, blue painter’s tape, sugar syrup, and a host of other “solutions” for improving bed adhesion. Ignore these. They are written for printers that require manual bed leveling, ship with warped parts, lack removable print surfaces, use rudimentary print surfaces, or suffer other shortcomings.
The one and only trick to PEI is to keep it clean. How do to this depends on just how contaminated the surface is. The biggest enemy is grease, and the biggest source of that grease is your fingers as you handle the sheet. No matter how you clean your sheet, try to avoid touching the PEI surface as much as possible. The PEI sheet used on the Mk3 is a wonder. When properly cleaned and cared for, printed parts will stick firmly enough to get a solid print, yet pop off easily when cooled.
There’s no magic to getting good 1st layer results and excellent bed adhesion with this surface. The only requirement is proper maintenance of the PEI surface and first layer (Live-Z) calibration to get the best results.
2.3.2. The riddle of adhesion
You’ve probably seen some of these guidelines before and may have wondered exactly why these simple-sounding steps work. Here’s an unscientific breakdown.
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Isopropyl alcohol and acetone work as solvents breaking apart grease molecules. These solvents do not completely dissolve grease, but do break it down far enough that it can be removed from surfaces easily.
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The more concentrated the solvent, the more effective it will be at a given volume. Those little 70% isopropyl wipes do work… on a shiny new PEI sheet. They’re just not effective in dealing with larger amounts of accumulated grease. This is why 91%+ alcohol is recommended.
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Acetone is even more effective, breaking up oxidation on the PEI surface, but can make the PEI surface brittle and prone to cracking if over-used.
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The amount of grease that any solvent will effectively break down is directly proportional to the volume of solvent to grease. The more you apply, the more grease it can effectively break down. The more concentrated the solvent, the more grease a given quantity can break down.
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Alcohol, acetone, and any other solution you apply directly to the bed is just going to move those broken-down grease and grime molecules around. Some will be picked up by wiping with a clean towel, but some will remain on the PEI sheet.
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A dunk under the sink with Dawn dish soap is the most effective method of cleaning. Dish soap is a surfactant 2 , not a solvent. It works in a fundamentally different way, bonding both grease and water molecules to wash away contaminants. The reason this is so effective is not because Dawn is “stronger”, but because there’s simply a much greater volume of Dawn and water and the grease is washed away from the PEI sheet.
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Windex, a wipe of finger grease, talcum powder or specialized release agents can be used to reduce adhesion when using hot, sticky materials that grip the PEI surface too firmly such as PETG. It is still a good idea to clean the PEI before a print to get an even surface, even if you will be applying a release agent for printing with sticky materials.
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If you are printing high-temperature materials (e.g. PETG at 260C on a 90C bed), test to make sure it will release once cool without damaging the PEI surface. You may want to use a glue stick or other release agents for these materials. Test on a sacrificial PEI surface if possible. See over adhesion, below.
RE: Thorough
Bobstro’s write up is probably the best I have seen. I have modeled my practices after his writings.
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Chuck H
3D Printer Review Blog
Sheets
I didn't order a sheet because in the manual, it says it can print PETG on either one just fine.
I am quite frustrated. Now I am trying to print something on PLA and I am having similar issues. I am cleaning the sheet for the PLA with a Alcohol prep pad and the first layer calibration seems to be OK. I have adjusted my live Z from anywhere between -300 and -760. It worked great for the benchy, the frog, and the Prusa logo at 760 but now PLA and PETG will not stick to the bed.
I have heard some guys use tape, glue or even hairspray. Any suggestions?
You can print PETG on either. Sometimes, some sheets take tinkering.
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Chuck H
3D Printer Review Blog
oh no
Thanks so much. I cleaned the PEI and I tried to print another downloaded file. The PLA got all gooped up at one section and popped off the whole print. Bummer
So now, I am printing the whistle. It seems to be doing great. So that would leave me to believe that some of the settings in slicer are not working for my print.
....UPDATE: So I started a print. It is about 75% done and one side lifted off the sheet. damn! As I look over at the printer, it finally broke off the sheet completely.
that was cool
Yea @cwbullet, i agree. That write up by @bobstro was cool as.
Smooth PEI might have too good adhesion
Well, I'm using textured sheet for PETG. I used the smooth sheet at first, but once I printed 3D benchy on it. It did not release when cold and when I tried to just yank the benchy off, it teared piece of the PEI surface with it.
Might have been different result if I had used some kind of spatula. Anyway, as I had ordered both sheets, I switched to textured one and have been happy ever since. The smooth sheet can still be used, even the damaged side as long as you locate the prints out of damaged spot. Anyway, I'm bit more experienced now and might get different results with the smooth sheet, but as the textured one works and I haven't switched back.
RE: Suggestion
I would never yank a print off either. Flex and flex until you get it to release. Pulling or yanking will eventually lead to damage.
Did you redo your z offset? It is possible you were too low for PETG on your PEI smooth. That will lead to over adhesion.
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Chuck H
3D Printer Review Blog
Smooth PEI works well with PETG but you do need to apply Windex or similar for separation
[...] The smooth sheet can still be used, even the damaged side as long as you locate the prints out of damaged spot. Anyway, I'm bit more experienced now and might get different results with the smooth sheet, but as the textured one works and I haven't switched back.
DEFINITELY put some separator agent on the smooth PEI before printing PETG. You want to clean the bed 1st to get rid of grease, but a spritz of Windex will help getting PETG off. The hotter you print PETG, the more important this is. I dedicate one smooth PEI surface for PETG and hot/sticky filaments, the other for PLA.
You can technically repair that damaged PEI surface, but it's a bit of work and messy. The other side should be fine.
RE: Smooth PEI works well with PETG but you do need to apply Windex or similar for separation
Yes I was aware of the windex trick, it was mentioned in some prusa's instructions, but didn't bother as it seemed to work so well even without. The difference was that my earlier parts had only small surface contact area on the sheet, or more precisely the surface contact on any one point was narrow, like a ring's perimeter, but the 3D Benchy had it all on one continuous flat and that did it. Anyway, textured sheet works really well, no windex, just wipe clean with IPA and you are ready for the next part.
Release agents
Put simply, I always use a release agent with stickier PETGs. Some do not need it and some will only need it on older print surfaces as they age and become seasoned. As you found out, you never know when that time will come.
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Chuck H
3D Printer Review Blog
When I read these threads I sometimes think I'm the only one around who doesn't have trouble getting stuff to stick. Just a little spritz of hairspray works for me. Never needed the Magic Goo or something like it.
Hair spray
When I read these threads I sometimes think I'm the only one around who doesn't have trouble getting stuff to stick. Just a little spritz of hairspray works for me. Never needed the Magic Goo or something like it.
And with PETG, it can assist as a release agent.
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Chuck H
3D Printer Review Blog
And, that's another thing that I've never had problems with on the Prusa. Just let it cool down, give the sheet a gentle twist, and it pops right off!