S3 glassbed chipping (tough PLA is really tough?)

[philippe44 0]

Hi - After many issue wrt adhesion with my UM2+ (

), I really decided that I had enough and broke the bank to buy an S3. I did a first large print and the result is interesting... once it was fully cold (a few hours to cool down) the print did not popup easily from the bed so I removed the bed to try out of the printer and when turning it upside down, it looks like the print sticks so well that, even before I tried to remove it (I really did not exercise strong force), some thin layers of glass were already detached and pulled by the print (chipping?), from the bed. Putting the whole thing in the cold allowed the print to separate from the bed but confirmed that thin layers of glass went with it. I've heard & read about that but never experienced it before (I'm not super-expert in printing, but I've been using my printers very regularly over the past 5 years)

 

Again, I did nothing special, it's just a large print at 0.15 with tough PLA, new reel. I did not pull strongly on the print and I saw immediately from the bottom side of the bed that glass was peeling off. So I moved from no adhesion with 2+ to too much adhesion breaking the bed with S3 (sigh)

 

On the positive side, now that I've cleaned everything and removed PVA support layer, the quality of the print, even at 0.15 is *amazing*

Edited July 27, 2021 by philippe44

[Smithy 1,146]

Did you apply some glue on the glass? If not do it, otherwise you will chip it again. The glue in that case is not for increasing adhesion but to have a protective layer.

[philippe44 0]

Thanks but no I did not b/c I wanted to keep the shiny 1st layer and I never had that issue with my UM2+ (including using tough PLA) in 5 years.

[Smithy 1,146]

I had the same issues, damaged some glass plates and did several tests with different adhesion agents. UHU Stick was the best and I now always apply a thicker layer to have enough protection.

 

You can try to use the Z-offset plugin and move the nozzle away from the glass a little bit. This decreases adhesion, but be careful that you don't use too much that your object still sticks to the bed.

[kevnvw 0]

In my experience, it is down to the filament itself if it comes off easily. For example: I live in the US and buy all my filament through matterhackers. Their black PLA comes right off the build plate but than their yellow PLA is impossible to get off if you didn't use some sort of UHU glue like Filament Junkie mentioned.

 

My recommendation would be that if you want a smooth and shiny back of the print, first do a small test print with that filament and see if it comes off easily. That's what I do because some prints I really need that shiny back.

[geert_2 558]

I use my "salt method" for PLA: wipe the glass with a tissue moistened with salt water, immediately prior to printing. This should leave a thin, almost invisible mist of salt on the glass. For PLA this greatly increases bonding while the bed is hot (compared to printing on bare glass), but there is no bonding at all when cold, so the prints come off by themself. I don't need to take the glass out of the printer anymore. Just re-wipe for the next print, and go.

 

For PET, it slightly reduces bonding, so the glass does not chip.

 

I haven't tried tough PLA yet.

 

For ABS, this method does not work, so I expect that it also won't work for other materials.

 

I do not recommend it for very narrow, high models like lantern poles: these tend to get knocked over. Then use some glue instead. But it works very well for my typical long and flat models, think of rulers and similar.

 

For the full (but old) manual on the salt method, see here:

https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/

 

 

This inverted prism is the maximum you can do with the salt method. This is a hard test, due to the tiny contact area and big overhangs that exert a lot of warping forces, and that curl up and cause the nozzle to bang hard into them.

 

[philippe44 0]

@geert_2: I will try again the salt method. I've tried on the UM2+ and did not get an improvment, but I'll certainly give it another run on this UMS3. I can't remember if you have a recommandation for dosage?

[geert_2 558]

The salt-concentration does not really matter. I just pour some salt in a bottle, and stir it. After wiping, it should just leave a *very thin mist* on the glass. Definitely no thick, crusty layers, that reduces bonding again. Thinner is better. I am not sure why it works, chemically or physically, but for me it works, so...

 

The photo with the gray above is about right (although contrast is enhanced in Photoshop, in reality it looks less), but in the photo with the red print, there is too much salt.

 

But before applying the salt water, make sure the glass is clean: clean all grease with alcohol or so. There should be no grease, no oil, no dirty fingerprints on the glass. And no soap either, because that too destroys bonding. After cleaning with isopropyl alcohol, wash with luke-warm pure tap water only. No soap, no window-washer, nothing but water. Then apply the salt water: you could moisten a tissue, or using a pipette drop a few drops on the glass, and wipe afterwards (I usually do it that way). Then immediately start the print.

 

I haven't used anything else in 6 years, I think. And I haven't taken the glass out of the printers in maybe 2 years.

 

During your first prints, stay with the printer and see if and how it works for you. Try small but critical models, like the inverted pyramids, to see how far you can go.

 

Bed temp needs to be between 55°C and 60°C.

 

Bonding may also depend on the brand of PLA, I mainly use colorFabb and Ultimaker now, and they work well.

 

[Travis7s 26]

I, too, have found that Tough PLA (especially Ultimaker brand) sticks incredibly well to clean glass. Like Smithy said, you can use the Z offset plugin to back it off a bit and still get reliable adhesion that is more reasonable to remove.