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selmo

Warning about T-Glase

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So this is a new one for me. I printed some parts in t-glase on my UM2, and they stuck to the glass really really well. TOO MUCH, in fact. It made some loud popping noises as it cooled, and even when fully cool, it was hard to get off. Sliding the thin metal blade spatula pried it off, gently and it sections.

Once I got the part off, I was looking at the nice smooth bottom side and I saw some defects. Looking closer, it was a weird bump. When I flexed the part, the bump popped and flew away. RIGHT INTO MY EYE!

GAH!

Looking at the print bed, I now have divots. The t-glase stuck so well to the glass that it pulled the glass up with it, leaving behind craters. It's hard to photograph, but here's a try.

t-glase chipped glass

I was able to get the glass chip out of my eye without a trip to the emergency room, and I've flipped the glass bed over. (and avoided printing with t-glase for the short term). I guess I need a replacement bed at some point.

Never had that happen with any other filament stock, and I didn't do anything too unusual in terms of temperatures, etc. Other parts I've done in t-glase without this issue, although these were he first parts I've printed in it with a large flat bottom area.

 

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I don't think waiting would have mattered -- in this case, the glass chipped as the part cooled -- I heard unusually loud pops before I even touched it (much louder than the usual ABS pops). The glass chip remained fully bonded to the PETG part long after I removed it from the printer (and only popped off when I flexed the part).

I was printing with a 50'C bed temp and it cooled to < 25'C before I attempted to remove it. Removing it was harder than PLA or ABS usually is, but that did not make any cracking noises or required a crow bar.

It's possible there were some microscratches on the glass that the PETG locked into as it extruded, and the size changes while cooling was enough to wedge open the scratches to full-blown cracks. Kinda like how ice will split rock. Maybe something about the extra strength of t-glase PETG combined with printing a large flat area on the part bottom.? Usually borosilicate glass doesn't have as much trouble with expansion / contraction.

The resulting divots were pretty clean "scoops" -- no cracks or partial chips around them They were in the center of the glass (where the most wear / scratching would be). Maybe printing in a less-worn corner would be better, but I'm a little hesitant to experiment, at least until I can easily and affordable get a new glass bed in the US. ;)

I'm usually pretty good about safety glasses, but I had no clue there was any danger....I wouldn't have flexed the part while looking so closely if I had any inkling that bump was part of the print bed glass! I've only seen this (so far) with t-glase (not ABS, PLA, Nylon, PET+, ninja, flex PLA, etc)

 

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Glass has lots of irregularities and is not smooth as it appears to our eye. Even in the pharma industry, there are issues with glass flakes/divets getting into the solution, depending on solution type and shocks to the packaging.

The glass is going to degrade over time, just as posted in the link before. Use something like glue or hairspray as a coating, or keep a good supply of glass plates around.

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I think patience is a solution... wait for the bed to cool more.. or even put your glass plate in de fridge... dont put a lot of force on the printed part..

 

The fridge works amazingly. I've had prints that wouldn't budge and 20 mins in the fridge allowed them to be taken off with barely any effort.

As far as getting a new bed, I would go to a glass supply store instead of getting one from Ultimaker.

 

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Yes, it can happen with ABS as well. While I had a large flat Black ABS print cooling, I heard a VERY loud pop. Looked over and it seemed fine... I contributed it to contraction noises as the ABS cools and broke parts of itself free from the glass. About 20 minutes later I go to remove the part and the bottom of the part had a thin sheet of glass stuck to it! Now I know what that loud pop was :)

As far as printing with T-Glase, I tend to put down a pretty heavy layer of hairspray (Aqua Net) with a paper towel. My thinking is that the thicker layer creates a little "cushion", hopefully preventing glass breakage... Who knows... works fine so far.

 

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I don't think waiting would have mattered -- in this case, the glass chipped as the part cooled -- I heard unusually loud pops before I even touched it (much louder than the usual ABS pops). The glass chip remained fully bonded to the PETG part long after I removed it from the printer (and only popped off when I flexed the part).

I was printing with a 50'C bed temp and it cooled to < 25'C before I attempted to remove it. Removing it was harder than PLA or ABS usually is, but that did not make any cracking noises or required a crow bar.

It's possible there were some microscratches on the glass that the PETG locked into as it extruded, and the size changes while cooling was enough to wedge open the scratches to full-blown cracks. Kinda like how ice will split rock. Maybe something about the extra strength of t-glase PETG combined with printing a large flat area on the part bottom.? Usually borosilicate glass doesn't have as much trouble with expansion / contraction.

The resulting divots were pretty clean "scoops" -- no cracks or partial chips around them They were in the center of the glass (where the most wear / scratching would be). Maybe printing in a less-worn corner would be better, but I'm a little hesitant to experiment, at least until I can easily and affordable get a new glass bed in the US. ;)

I'm usually pretty good about safety glasses, but I had no clue there was any danger....I wouldn't have flexed the part while looking so closely if I had any inkling that bump was part of the print bed glass! I've only seen this (so far) with t-glase (not ABS, PLA, Nylon, PET+, ninja, flex PLA, etc)

 

Couldn't you just go to your local glass shop and get them to cut you a build plate sized piece of glass?

 

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This also happened to me, but ill admit to jamming a butterknife between the model and plate and hammering at it with a book. I simply used too much glue and over too much surface area and it pulled an ultra thin wafer of glass of the plate. I just use the other side now, no biggie, i learnt my lesson. If you dont want it to happen, then just use rafts, they never let me down.

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Mine was using standard black PLA form colorfabb and glue called prittstick power. I guess its a lot stronger than the usual prittstick. I only bought it as the original prittstick was lumpy and this one wasnt, but ill try and get some cheapo glue like the one supplied. I always water the glue down from now on when it is on the plate to make sure its weaker and use the upside-down air can trick to get it to come off better.

I think its the kind of thing that only happens once...i hope, or its off to get some more glass which shouldnt cost to much so its not the end of the world.

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Usually borosilicate glass doesn't have as much trouble with expansion / contraction.

I need to disagree with you here. Boronsilicate glassware does NOT like expansion/contraction AT ALL.

You can't put BoronSilicate glass on an electric burner, it will shatter. You can't pull it from refrig and place in an oven--it will shatter, practically speaking. This from many decades of use in controlled settings. Coors porcelain labware? Same result. These types of heat resistant glass/ceramics DO have their limits.

There is basically NO guaranteed flexibility in BoronSilicate/Pyrex glass.

Sorry to be the bearer of such unpleasant news, but this error speak needed to be addressed.

3Dw

 

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RE: warning re: [printing with] T-glase,

a set of .STL files was released last week by an altruistic soul/public figure who is trying to save the world, one hydroponic lettuce plant at a time, apparently.

He's swearing by the mini-lutz as being the best machine for the use of t-glase filament. Yes, he has a UM2, and took specific time out to pan it as being more trouble than he could overcome. So, he's recommending w/OUT reservation the mini-lutz if one is going to work in T-glase which he is promoting.

That was a disappointing read re: UM2. I wrote him, with a couple of suggestions to improve his experience. Was promised a response in 48 hrs...it's been 96 hrs---would guess no reply is coming. :???:

A man convinced against his will

is of the same opinion still.

----------------------Dale Carnegie

 

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Old Thread, but same problem here. After printing PETG with 90° bed and 230° nozzle temperature, i had some spots of broken glas. Also i heard some silent cracking noise during the parts cooling down.

I've done around 500 hours worth of printing with PETG so far, and no cracked glass yet (finger crossed). Maybe the 90C bed temp could be a cause of cracks. 75C has worked well for me. Popping noises are heard for 20 minutes or more after printing ends, but it's only the part separating from the glass

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