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I'm pretty new to printing PETG, and my Creality Ender 3 now has a glass print bed. I've done some research, and it looks like a pretty bad idea to try and print PETG on a pure glass surface for fear of the print pulling chunks of glass along with it.

So, I've looked into various bed adhesion options. I've already used blue tape, but I'll need to purchase some wide stuff, and in the meantime, I want to investigate using PVA-based glue stick. However, one question does come to mind: how can I set the bed-nozzle distance after applying the glue stick layer?

Do I even need to? Will the extruded plastic just crush it into the build plate without a problem, saving me the trouble of lowering the build plate? My normal method of sliding a paper sheet under the nozzle at Z = 0 mm would take the glue stick layer along with it if I tried that.

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How much glue do you put on it? I use PVA based spray, barely visible, very evenly spread and no problem whatsoever of sticking paper to the glue layer.

Just level the bed as you normally would and apply a sparsely applied coat of glue, preferably from a spray can. Note that glue stick dissolves in water, so you can distribute the glue with a moist cloth preventing globs or thick layers of glue.

Having printed literally kilometers of PETG on various build platforms (various glass sheets with or without PVA based glue, Aluminium and PEI), chipping of glass is not something I have seen happening (this part is added after comments on adhesion and glass chipping in comments). Perhaps, in case of chipping, if the glass might be of very low quality, then chipping may occur. Whether your glass is of decent quality can be tested, just print on one side, and if it chips you always have the other side. My Ultimaker 3E sheet of glass has a small chip taken out of the surface, but that was caused by not carefully removing the print, tip is to not pry with the corner of a too thick painters spatula, the corner can dig into the glass if force is used. This was not caused by the adhesion of the print but a user error, now, years later and many more kilometers of PETG, no more extra chips are out of the sheet.

Printing on PEI with PETG is another story, PETG just fuses to PEI and is very difficult to remove, a PVA based glue helps, but from experience, still prints were very hard to remove.

Invest in a can of build plate adhesion spray, it lasts long, never gives you problems with adhesion and probably is even cheaper than glue sticks (per mass unit).

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    $\begingroup$ Not if you "liberate" glue sticks from the supply cabinet at work :-) $\endgroup$
    – Carl Witthoft
    Commented Feb 1, 2019 at 15:53
  • $\begingroup$ Which is how I intended to do it. Is the layer height of a glue stick application negligible? $\endgroup$
    – ifconfig
    Commented Feb 1, 2019 at 16:01
  • $\begingroup$ @ifconfig Unless you apply a lot of it, it should not be a problem. To get proper adhesion, you only need a very thin film. That is easy with a spray can. Sometimes you see pictures on the web where people use too much glue stick, that is not necessary. You can also use strong hairspray. However, some are better than others and not all brands are the same over the world. I'm using 3DLAC for several years now, that is very good spray. $\endgroup$
    – 0scar ♦
    Commented Feb 1, 2019 at 17:05
  • $\begingroup$ Hrm, so I see. But you're saying that even if I want to use my giant collection of glue sticks, I should be okay without lowering the bed as long as I don't apply a super thick layer? $\endgroup$
    – ifconfig
    Commented Feb 1, 2019 at 18:12

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