PETG on smooth PEI sheets  

Re: PETG on smooth PEI sheets

Try wiping the PEI with your fingers before a PETG print. It works as well as Windex many times. Joan's "forehead wipe" technique is usually all I need. Once I get it right, I'm usually good for several prints.

A hot bed can help hold the sticky filament away from the nozzle on lower layers. It's a trade-off. Definitely let the PEI cool before removal.

Re: PETG on smooth PEI sheets

Honestly even with the bed at only 65, PET was already sticking good enough to make a perfect skirt.
To make sure I was doing tests worth something, I wiped clean the PEI at every test.

Re: PETG on smooth PEI sheets

I think it depends on the brand you're using. MakerGeeks recommend 255C/60C and AmazonBasic 240C/80C.
I'm printing with 60C bed temp and raise up to 70C if needed without any glue sticks.

Re: PETG on smooth PEI sheets

It really depends on what brand of PETG you are printing with. For example When I was first printing with PETG for the R2 parts I used orange Extrudr PETG and the only change I made was to lower the nozzle temperature to 220°C from the default generic PETG settings to reduce stringing and oozing. With this PETG it is possible to print without a separator although I would not recommend doing so as cleaning the bed is a pain if you don't.

However I now use Rigid Ink PETG and that is a whole different kettle of fish. This PETG loves to stick to hot mettle and so requiers a 0.2mm Z offset and a very hot bed (115°C with a 225°C nozzle) for the first layer so a separator such as Windolene (Windex in the US) is absolutely essential). After the first layer I drop the bed temperature to 90°C (I don't go lower to avoid introducing warping) and up the nozzle temperature to 240°C (with an increase in fan speed to 40%-75% to stop the stringing)

The main advantage of using window cleaner as a separator is that it also acts as a decent bed cleaner between prints and as such is a win-win.

Regards,
Martin

Re: PETG on smooth PEI sheets

If anybody is interested, the spool I was currently using is black PET-G "T-glass" from Technology Outlet, which gives me similar results to the old "regular" PETG from Prusa in terms of bed adhesion and temperature, but I didn't try to print tall objects with Prusa's one yet.

I wonder if anybody has some print-bed tests done with E3D's "Edge"? More/less sticky to the PEI?
I have a roll that I didn't open yet.

Re: PETG on smooth PEI sheets

If anybody is interested, the spool I was currently using is black PET-G "T-glass" from Technology Outlet, which gives me similar results to the old "regular" PETG from Prusa in terms of bed adhesion and temperature, but I didn't try to print tall objects with Prusa's one yet.

I wonder if anybody has some print-bed tests done with E3D's "Edge"? More/less sticky to the PEI?
I have a roll that I didn't open yet.

I would suggest you simply test it for yourself. Start with small (flat) objects and low temp going up, if required. The properties of the used sheet is also changing all the time. For example if you print same model in PETG 10x on the same place it will bond better and better.

Re: PETG on smooth PEI sheets

The idea of using a window cleaner seems more intriguing than gluestick, however what's exactly acting as a cleaning, and next separating agent in there?

I cannot find the technical data sheet. Is it mostly isopropyl alchohol?

Some images mention "cleans with vinegar", but I wouldn't repeatedly use anything that vaporizes acetic acid next to copper components.

Here in Italy they sell "denaturated" alcohol, which is ethanol with some extra crap added to make it undrinkable. Exact composition varies, but the added crap makes this hardly usable for window cleaning, as it does leave oily stains.

That oily finish might be what's useful here..
Unfortunately, they frequently add perfumes which make it obnoxious over time.

Re: PETG on smooth PEI sheets

Window cleaner doesn't really clean the surface. It gives you a small separator so PETG doesn't glue to the PEI sheet. You can use any window cleaner which is IPA based so it doesn't damage the PEI sheet.

Re: PETG on smooth PEI sheets

I believe it's the anti-streaking and other additives to Windex that make it ideal. It cleans away gunk, provides and even surface, but with just enough other stuff to weaken the PEI grip. I'm sure other sprays or liquids would work, but it's had to beat something like Windex for being handy and not making a mess.

Re: PETG on smooth PEI sheets

Also I believe everyone is referring to the original formula Windex not the trendy vinegar based version.

RE: PETG on smooth PEI sheets

@bobstro

please would you explain or link Joan's "forehead wipe" technique in more detail.

thanks!

RE: PETG on smooth PEI sheets

For PETG and ABS, I found a smoother Textured PEI sheet China that prevent overly strong bonds to the build plate.  

RE: PETG on smooth PEI sheets

@charles-h13

How are your experiences with it? Would you publish the link to the product?

RE: PETG on smooth PEI sheets

I had to come home to get the link.  I have found that older textured (well used) sheets stick too much with PETG and ABS.  I bought a sheet on eBay that seems to work better at releasing these filaments.  

https://www.ebay.com/itm/PEI-Double-Sided-Durable-Textured-Spring-Heat-Bed-Steel-Sheet-For-Prusa-I3-MK3/392579025268?hash=item5b67888974:g:VA4AAOSw9-ld7sx9

RE: PETG on smooth PEI sheets

One more side note. I'm using same sheet for PLA and PETG prints. Most of the time I'm printing in PLA but sometimes in PETG. Based on my observation the strong bond only applies if I do multple PETG prints in a row. It bonds better and better each print. Otherwise the PLA prints leaves some particles which are enough for easy separation without using any special technique.

BTW: Still using first sheet, first side after a year. Prusa flex sheets became really good if not damaged accidentally 

RE: PETG on smooth PEI sheets

Posted by: @karl-herbert

please would you explain or link Joan's "forehead wipe" technique in more detail.

@joantabb has a knack for identifying simple workable solutions for things. Last year as many of us were still figuring out the PEI sheets, she suggested that literally wiping across one's forehead then giving the sheet a wipe is effective at loosening the hold of most PETG on the smooth PEI sheets. I've adopted wiping the fingers on PEI before printing PETG ever since and it has worked very well. The only time this failed was with high-temp (270C) PETG which required glue stick.

Of course, swapping back to PLA is miserable. I recommend dedicating a sheet or at least one side of a sheet to PETG and another to PLA.