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toilet-ovule-add

(Tough) PLA residue when removing

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To get a smoother surface on a printed object i changed the initial layer height and flow when printing the shown lid of a small box.

After printing i removed the glass plate and inspected the lid's top layer, and it was perfectly smooth.

The lid was sticking like glue, so cooled the glass plate to shrink the glass to cause some tension between the printed object and the glass plate.

This worked perfect, the printed lid came loos, but kept stinking on one place, and it seemed if ice-crystals were formed at that location.

After waiting 30 mins to get the temperature change back to room temperature the crystals were still there and the printed lid was still sticking

like glue at a small part of the object.

After applying some force it came loose, but with some damage. A transparant residue (PLA?) remained on the glass plate where the printed lid was damaged.

The damaged part of the printed lid was also slightly thicker than the remaining smooth surface.

 

Can anyone tell what that residue can be ? Are there better ways to remove a tough PLA printed object ?

 

 

 

Damaged printed part and residue on  glassplate

IMG_5087.thumb.JPG.756382acd6e34777d84d9823e4d3ec8d.JPG

 

Hard to see on the picture, but lower printed lid is much smoother the upper initial printed lid.

image.png.cd4feece54c86280edea679af851582f.png

 

 

 

Cheers,

Peter

 

IMG_5089.JPG

Extra Fine Tradfri Lid.curaprofile

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Hmmmmm.... 

 

It was impossible to remove the residue, due to the fact there was no residue on the plate.

Seemed that the tough PLA was stronger than the glass. The residue was on the print and not on the glass.

Glass residue... The glass plate chipped, another lesson learned. Tough PLA is almost as strong as ABS and the same rule seems to apply here. Will use the other side of the glass and try again with a thin layer of glue.

 

Also see thread; 

 

 

 

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I always apply a thin layer of glue, not always for adhesion, but also to protect the glass in such hard cases. Normally Tough PLA stick as good as normal PLA, so maybe your glass was not clean enough.

 

And chipping the glass is easy. I printed with ABS and applied 3DLac on the glass. Worked perfectly, but I forgot to remove the 3DLac layer after the ABS print and chipped also my glass a little bit.

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1 hour ago, Smithy said:

...so maybe your glass was not clean enough.

 

Why should the glass not be clean enough? Badly cleaned glass prevents proper bonding, i got the opposite result. It seems that Tough PLA sticks better than normal PLA and as good as ABS. With 'normal' PLA the designs do come off easily. Always clean the glass plate with some water and ammonia, with constant results. 

Also used a PVA raft many times, but to get the smoothest surface on one side of the print decided this time to print straight on the glass. Will retry the print now with some glue and a damp cloth to distribute the glue evenly. 

Edited by toilet-ovule-add

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13 minutes ago, toilet-ovule-add said:

Why should the glass not be clean enough? Badly cleaned glass prevents proper bonding, i got the opposite result. It seems that Tough PLA sticks better than normal PLA and as good as ABS.

 

Because it was dirty from the last print? But it was just a hint - everyone should have his own experiences and workflows and they can be completely different because for me ABS sticks very bad to the glass, so obviously the opposite to your ABS.

 

Anyway - good luck...

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For bonding PLA to the glass I use my "salt method". In short, it goes as follows:

 

First, thoroughly clean the glass. Then clean again with tap water only (no soap, no window washer, nothing).

 

Then gently wipe the glass with a tissue moistened with *salt water*. Gently keep wiping, until it dries into a thin, almost invisible mist of salt stuck to the glass. This takes less than a minute, and can be done while the printer is warming up for the next print.

 

For PLA and PLA/PHA, this "salt method" gives very good bonding when the glass is hot, but no bonding at all when cold at room temp. So models come off by themself after cooling down, without any difficulty nor damage.

 

For Ultimaker PLA and colorFabb PLA/PHA it works very well. But for ABS and PET it does not work.

 

Also, for high but thin objects, like vertical lantern poles, it is not optimal: the salt is not flexible and does not absorb shocks very well, when the nozzle bumps into a model. But since my models are mainly large and low, this is of no concern for me.

 

I have no idea if this would work for tough PLA, but it might be worth trying? If you try, use the damaged side of the glass for your tests. Feedback on the results would be very welcome.

 

See the full text here (yes I know, the text is way too long and I should update it, but it is still usable):

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

 

saltmethod3.jpg.b36952a07208ed06aea2e5142716121c.jpg

 

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Ok, 

 

Tried the glue stick the past 24 hours. To get a smooth surface i dissolved the glue with some drops of water to spread the glue evenly.
After printing the object came of easily. There was some warping on the edges and PLA did not bond perfectly everywhere, e.g. at the lower end of the ' ä ' and at some places in the WiFi symbol. Probably due to the fact that the glue was not spread evenly?

 

Also you can clearly see the water pattern at the surface. So will try the salt method next to see if it makes a difference. 
 

 

IMG_5093.JPG

Edited by toilet-ovule-add

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This is how the bottom generally looks when using the salt method.

 

On top I focused the camera on the surface itself. At the bottom I focused on the reflections of a desktop fan in that surface. (Unfortunately I couldn't get them both in focus at the same time.) So the surface is quite glossy, with very small pits due to the salt particles.

underside_mirror.thumb.jpg.d9e8c12251778b0a33338a0eac202c6f.jpg

 

Inverted pyramids, thus models with a very small baseplate and huge overhangs, are likely to lift, due to the high shrinking forces and the nozzle bumping brutally into the edges that curl up. This was a test model specially designed to test how far I could go in inverted prisms.

DSCN5814.thumb.JPG.579cd13d93beed9cc55ec4cb5ab6c366.JPG

 

This is how the bottom usually looks in close-up. Nozzle size is 0.4mm, to give an idea of magnification. Often around corners a tiny area of 0.5mm lifts, but usually that is all. This is best visible in the top-right corner here. The pits caused by the salt are also well visible here: it looks a bit like corrosion.

DSCN4938.thumb.JPG.90124a14e04953b171581afa5e8f9e9a.JPG

 

Another inverted test prism. Corners did lift, the center didn't, and the model could be completed.

DSCN4889.thumb.JPG.73f000e965b9b6fb6dd8cf9087767853.JPG

 

So this is what you could expect for normal PLA and PLA/PHA.

 

With my printer and materials, bonding is best at a glass temp of 60°C. Usually I can lift the whole printer when pulling on the model. At 40°C models are likely to pop off suddenly in mid print. At 70°C the models stay too soft (this is too high above glass transition temp of PLA), and they tend to peel off. At room temp of 20°C bonding is nihil. So I always leave the glass plate in the printer and just wait untill it has cooled down.

 

I would very much welcome feedback on other materials, especially those related to PLA, such as Polyalchemy Elixir, Tough PLA, high temp PLA, wood- and other particle-filled versions, and similar. Also on PET and polyesters, although I don't expect it to work well there.

 

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