I've been experimenting with printing on bare glass and I may have a successful method.
First layer is crucial. Your first layer ought to be slightly squished for good adherence. There is a lot of advice out there about first layer but I've found these things to be relevant for the Wilson II.
Calibrate esteps, you need to be sure you're extruding the right amount of filament.
- Measure filament diameter and set accordingly in slicer. This also helps to ensure your machine is extruding the right amount of filament. I'm using Atomic PLA and it is actually 1.72 mm.
Check that the x-axis is level. I had one corner of my print not adhering and sometimes curling up until I did this.
Tune Z Offset. Larger value for more squish, lower for less.
Clean the glass with denatured alcohol and paper towel or lint free cloth. I've been using isopropyl alcohol and it works but I've read that I should be using denatured alcohol. Point is the glass needs to be squeaky clean.
Turn up the heat. I think Cura defaults the bed temperature at 50° or 55°. According to the Atomic Filament FAQ that bed temperature ought to be 58° - 62°. I've read elsewhere that bed temp should be as high as 70° for printing PLA on glass. I've had success at 62°.
Use a brim for small parts. If the part your printing has very little surface contact use brim support when slicing. In Cura the setting is called "Platform adhesion type" In my limited experience I'm not sure how much surface contact requires a brim and how much doesn't. If it's a small part and comes loose during printing then add a brim.
That's it. I haven't used my glue stick for quite a few prints now and prints come off the glass very easily after they cool down. Please share any advice or results you've experienced on this topic.