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PETG eats the glassbed, what to do?

Posted by Koenig 
PETG eats the glassbed, what to do?
September 05, 2015 01:22PM
Sometimes when I print with PETG it takes a chunk out of my glassbed, why does it do that, how to prevent it?

I print the part and when it is finished I let it cool off, usually it just pops of the bed, but sometimes it takes a piece of my borosilicate glassbed with it.

I'm not applying force or anything, the glasschunk is just sitting underneath the part I just printed when I lift it off, still stuck to the part and impossible to get loose.

I print with the bed at 70C for the first few layers then 65C.
Re: PETG eats the glassbed, what to do?
September 05, 2015 01:36PM
If you have an aluminium heat spreader under the glass, then you can use ordinary float glass instead of borosilicate (I also know of people who use float glass without a heat spreader, although I wouldn't recommend it). I don't know whether you would have any less problems with chips sticking to the print from float glass than borosilicate, but at least it's cheaper to replace.


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Re: PETG eats the glassbed, what to do?
September 05, 2015 01:45PM
Quote
dc42
If you have an aluminium heat spreader under the glass, then you can use ordinary float glass instead of borosilicate (I also know of people who use float glass without a heat spreader, although I wouldn't recommend it). I don't know whether you would have any less problems with chips sticking to the print from float glass than borosilicate, but at least it's cheaper to replace.

Think I will go for that the next go around!

Is this something common, I've not seen anything about it before, I'm new to this so what I have seen is very limited, I was thinking bad quality glass first, came from china.

Now I put on a brand new borosilicate from UK, we'll se how that goes.
Re: PETG eats the glassbed, what to do?
September 05, 2015 02:41PM
It happens when you have scratches in your glass. The heating/cooling stresses the glass at a scratch, and a print over that scratch can break out chips. I've had ABS do the same thing.
Re: PETG eats the glassbed, what to do?
September 05, 2015 03:32PM
Quote
Dirty Steve
It happens when you have scratches in your glass. The heating/cooling stresses the glass at a scratch, and a print over that scratch can break out chips. I've had ABS do the same thing.

Must be bad quality of the china-glass then, first time it happened the glass was fairly new, had printed some PLA on it and no nozzle crashes or the like had happened.
It happened a couple of times on and off, just moved the "print" to another area.
Today it happened once and the glass was now so damaged so I turned it around and the first print on that side took a really big bite out of it, hence this thread.

Since it had happened before, I had already ordered a spare.
I hope this brittish glass is of better quality then.
Re: PETG eats the glassbed, what to do?
September 06, 2015 02:40AM
Perhaps try hair spray. It stuck for me, but not too hard.


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Re: PETG eats the glassbed, what to do?
October 17, 2015 03:14PM
Mess with temperature and first-layer heights. If that doesn't work, try a different surface.

If the glass just pops out, it sounds like you have bad glass, so maybe replace that with nicer glass or a sheet of aluminum. Then put on glue stick, blue tape, or hairspray -- or PEI, if you want to do that.
Re: PETG eats the glassbed, what to do?
October 29, 2015 02:36PM
its not only PETG, my ABS did the same, don't think its material related, happened to 2 of my borosilicate glass, I haven't been bothered with glass since, just print straight on the MK3 bed with solution I bought on ebay for 8 euro, not a bit of lift, no more broken glass. it stick even better than the glass

Edited 1 time(s). Last edit at 10/29/2015 02:37PM by deaconfrost.
Re: PETG eats the glassbed, what to do?
July 22, 2016 10:36AM
It's not bad quality glass, although I have heard that.. usually from some know it all, who really doesn't know it all!

Motedis warns against using PET-G on glass "as it will chip it".. if you bother to view their video.. their text says a generic "pritn on glass.
[www.motedis.com]

Also a thread here on Ultimaker fora:
[ultimaker.com]

I have had several plates ruined by various types of materials.. only when I used hairspray though.. so I no longer use that. Happened on all sorts of different types of glass, and also high quality Boro glass.


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Re: PETG eats the glassbed, what to do?
July 23, 2016 10:11AM
Anyone been printing PETG on bare glass for a while and not chipped the glass? I've gotten quite a few hours on my delta printing PETG and just now am getting small little chips. Granted, the mirror I'm printing on has been abused a little since it was what I used when first setting up and calibrating it. There were many times where the hardened steel nozzle slammed into the glass and/or scraped across the surface.

I'm wondering if I'm getting chips coming out of my glass because it has been scratched up a lot. Maybe I should consider the printing surface a consumable and start buying a couple replacements.

Edited 1 time(s). Last edit at 07/23/2016 10:11AM by MrBaz.
Re: PETG eats the glassbed, what to do?
July 23, 2016 03:24PM
This article sounds interesting. At least I found it worth a shot for $12 and ordered a glass screen protector from Amazon. Shame I can't get the exact glass size, but got one close enough to try with PETG and hopefully it won't eat the glass bed.
Re: PETG eats the glassbed, what to do?
July 23, 2016 05:28PM
In addition to adhering to a number of materials better, Kapton tape provides a sacrificial surface if the part over-adheres.
Re: PETG eats the glassbed, what to do?
July 23, 2016 10:25PM
Sacrificial Kapton? I use 5 mil Kapton on my printer's bed and it lasts for months of daily ABS printing. When I want to print PLA I just apply blue painter's tape on top of the Kapton and leave the heater off.

Regarding screen protectors, they may have an oliophobic coatings to prevent fingerprints and smudges which may interfere with print adhesion.


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Re: PETG eats the glassbed, what to do?
July 26, 2016 08:42PM
it happened to me with 2 borosilicate glass from UK, I now no longer use glass nor a heatbed
Re: PETG eats the glassbed, what to do?
July 27, 2016 06:20PM
If I have to replace a very easily affordable mirror once or twice a year for all the printing I do, I find that acceptable.
Re: PETG eats the glassbed, what to do?
July 27, 2016 06:42PM
With 25 or so printed PETG parts, I've had it take 4 chunks of glass and these parts where no stuck. After letting them cool, they lifted off and had a chunk of glass with them. I'm waiting for my Kapton to arrive to print any more, but I'd be happy with 1-2 pieces of glass a year, but I feel as though it would be a lot more than that at this rate.

Edit: The glass screen protectors might be sacrificial, but I have not had any luck getting the PETG to actually stick to them yet. Probably as someone said, the finger print coating is getting in the way.

Edited 1 time(s). Last edit at 07/27/2016 06:43PM by PDBeal.
Re: PETG eats the glassbed, what to do?
July 28, 2016 06:49AM
my 2 glass went within a month, second glass had a massive chunk gone after first print, like PDBeal, it cools down and came off easily but with the chunk of glass together, not stuck
Re: PETG eats the glassbed, what to do?
July 28, 2016 06:55AM
Have you considered using aluminum? Cast tooling plate is flat enough to print on and will never break and never cut you...


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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: PETG eats the glassbed, what to do?
January 08, 2018 04:13AM
I had the same problem. Broke 3 glasses before finding the solution:

KEEP THE GLASS CLEAN!

When first going for PETg, it seemed to me that either the objects do not stick at all, or they will stick so well that it's hard to remove. If the bed was not hot enough (70C), or the leveling was incorrect, there was no adhesion. Increasing the temperature to 75C, the printed objects got stuck for good. With larger (about 20cm) objects the loss was was 1 glass / 1 object. The glasses were normal 2mm "photo frame" glass from two different and well reputable local sources. One of the sources advertises supplying Pilkington brand.

The solution was to use clean the glass bed perfectly: no fingerprints, no signs of grease, nothing, just plain shining clean glass, clean as a camera lens. And voila, the problem was gone! Adhesion depends now nicely on bed temperature, which I have set to 73C.

The filament I use is Real Filament PETg. The cleaning stuff is normal alcohol-based window cleaner, which leaves some residues to be removed with a clean napkin.

Hope this helps.
Re: PETG eats the glassbed, what to do?
January 08, 2018 04:42AM
Float glass and 3DLac. Borosilicate is known to easily chip but float glass does not. I use 6mm thick float glass and never had any problem with chipping or breaking. This 340 mm diameter table was printed with T-Glass\PET-G and simply fell of when the glass cooled. [forums.reprap.org]. Oh, and I do things like this too [www.youtube.com]


[somei3deas.wordpress.com]
Re: PETG eats the glassbed, what to do?
January 19, 2018 09:08PM
I use PETG no heated bed turned on with plain 1/4 glass with a coating of water soluble stick glue and had no problem . Key to removal don't let the part cool on there over night just a few minutes and catch under the edge with a razor blade and tap blade with a wooden or printed block. No need to clean glass every time until glue builds up too much. Worst case take the glass plate off and soak in warm water. And to think when we were beginners we couldn't get prints to stick. N.B. won't work for Nylon I am told.
Re: PETG eats the glassbed, what to do?
January 20, 2018 05:26AM
Hello,
I am printing on Glass with kapton tape on it an di do not have an problems with removing the print from it.
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