Shattered Glass

Has anyone ever had a glass bed just shatter in place? I’ve been printing on this piece for months and, in fact, the model I’m printing is still sitting in the middle, still printing, yet the glass all around it shattered.

I’m figuring it’s a thermal shock, but I’ve been printing at the same temperatures (210/70) for most of the last two months.

I’ve never seen anyone report this before.

The only change I’d made recently was to put a piece of tape on each of my 4 corner brackets because I had a couple of prints fail because the glass shifted. The corner brackets seemed to be getting loose over time.

This glass is from 3DPC. It’s from the Longer LK1. I bought 5 of them; one for this printer and 4 for the Frankenprinter project.

I would have thought that glass intended for a 3D printer would be able to take the temperature swings. I would have expected something like this from standard window glass but I had figured I was safe ordering the Longer LK1 glass since I figured 3D printing is what it was designed for.

I’m shocked, frankly.

Cant comment onnhaving this happen to me. Only a chunk takken out printing pla of all things. Perhaps it was a flaw in the glass that took time to finally release?

Is this current print a “new” print? Or one youve done multiple times?

Its hard to identify if/where the crack started. Do you normally just let the prints pop off, or do you use a scraper/razer blade? Also do you use a bed adhesion like glue or hairspray? Im wondering if a scratch/gouge could cause this

Well, the analysis has been interesting.

The part I was printing was basically the 14th more-or-less identical part, printed in the same material. They’re dividers for a storage case.

I use glue as a release agent because this particular PLA sticks to the glass something fierce. Without glue, it takes a spatula hit with a hammer at maybe a 3 to 5 degree angle to knock a print off even after the glass has cooled. Other PLA from 3DPC practically pops off on it’s own, but not this stuff. It’s the Black Matte PLA, for what it’s worth.

Having said that, I am conscious of not chipping the glass (hence the very low strike angle, but the removal of the glass fragments has taught me something.

Earlier in the week, I lost a pair of large prints when the print head scraped against the model’s infill and shifted the glass. It appears that the corner brackets I had been using for the last couple of months, printed in PLA-F (not flexible) had been getting loose. Perhaps they had shrunk? I don’t know what caused it, but they were a lot more easily removed than when I initially made them and it had reached a point where the glass was shifting during a print.

My solution was to put a single strip of double-sided Scotch Tape on the underside of the glass at each corner to make sure the brackets wouldn’t slip. The shattered glass was kind enough to stay put while the print finished, and when I examined it as the model was printing, I noticed the purge line was laid down at an angle and starting farther from the edge than it should have, indicating that the glass had shattered before the printing began.

That ruled out my initial theories that either the nozzle had impacted the glass, or the change in temperature between the glass and the hot PLA had caused a thermal fracture. Mind you, the facts that I’d been printing on this glass for months, that particular GCode had never resulted in an impact and the glass was designed for 3D Printers in the first place had me doubting those theories. That’s when I reached out to the forum as it was still printing on the last in-place glass fragment.

When it was done, I was surprised to learn was just how hard it was to get the corner brackets off the pieces of glass.

Based on that, I now think the brackets held are so tightly by that single strip of tape in the corners, that as the bed heated up and expanded, it appears to have literally pulled the glass apart.

I was thinking as looking at the photos that the glass had broken from buckling and wondered how it was secured in the corners.

Is that regular glass or bonon or similar high temp glass? I have seen regular glass shatter a little scratch and heat and it pops. I have never heard of pyrex/ boron glass breaking. The printer I have made the most prints on is my little mono price it is 4 years old, the B/S glass on it has had almost 5 prints a week on it for all 4 years. Not a single issue.

My guess is it is not a flexible glass but regular glass that a tiny amount of flex will either break it or micro fracture it causing it to shatter later. It can also break under heat stress. The family of glass that is ‘softer’ and made to tolerate deflection it is unlikely you could break it in the way it would take a sharp impact. Some of the new glasses by corning or Schott will noticeably bend before they break, bend a lot in fact.

So far as I’ve ever seen, glass that is subject to lateral compression (buckling) tends to throw off scalloped fragments. Frankly, I’ve never seen a piece of glass fail like this that wasn’t intentionally cut.

I was truly amazed at how much force it took to get the corner brackets off the fragments. It was held on by about 2cm of double-sided Scotch tape on each corner and I had to use a spatula and a hammer to free them. This is why I now think that it failed under tension as the aluminum bed heated up, expanded and the tape provided zero give and simply pulled the glass apart. The fact that the purge line went on crooked also indicates that that fracture happened during the heating phase.

Over the months, I’ve seen people post pictures of glass plates that suffered nozzle impacts, 3D printing nerd broke the glass on a giant printer by trying to pull a model off, and of course, people have dropped the glass, but I’ve never seen a failure quite like this.

You bring up a good point. Hopefully someone from 3DPC will weight in on this and tell me what their Longer LK1 / CR10 glass is actually made of.

Would guess that if it wasn’t specifically mentioned it is just plain glass. I could be wrong but when I bought the glass for the mono price it was marketed as boron silicate all over the place.

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HI Everyone

I had a look and the Creality glass is listed as being Silicate glass, It is supposed to be heat treated. I cannot find the same detail with the Longer Glass, It does actually come from the manufacture so I would have always assumed it was borsaletic glass. (heat treated after cutting and buffing but I cannot find any documentation to confirm this.


Thanks for looking into it.

no problem, Luckily I have had to dig for some pretty abstract facts and know where to find the weird spec sheets.