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Smithy

Tough PLA bed adhesion

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I struggle since some weeks with my Tough PLA prints, because they stick too well to the print bed on my S5. I never have seen such issues on the UM3, so I assume due to the better multi-point bed leveling on the S5, I simply get a better adhesion than on the UM3.

 

However, I did some tests with different "helpers" and here are my results. Maybe it helps if someone has similar problems.

 

How I did these tests?

I printed the same object several times on my UM S5 with UM Tough PLA White, Cura 3.6 default settings for 0.15 layer height. After the print, I waited until the glass got room temperatures.

 

  • A thick layer of glue (I just used the glue stick and painted the glass, 2 times)
    No problems during the print, no warping.
    The printed part came off easily with the help of a small spatula.
     
  • A thin layer of glue (distributed with a wet tissue)
    Sticks very well on the glass, no warping at the corners.
    But sticks a little bit too well, so it was hard to get the object off the glass after the bed cooled down.
     
  • Magigoo Stick
    It was hard to get the object off the glass, even with watering the part.
    Not recommended!
     
  • Dimafix Spray
    No warping, but sticks to the glass like hell. No chance to get the object off after cooling down. Even with watering around the object and use of spatulas. 
    Not recommended!
     
  • Plain, proper cleaned glass
    The material sticks like hell on the glass, nearly no chance to get it off. I even damaged one small spatula and I had the luck that I haven't destroyed the glass itself.
    Not recommended!
     
  • 3DLac Spray
    No warping, but sticks also too well and my glass chipped off a little bit when I have removed the part. This test wasn't really planned to do, but I forgot to clean the glass after printed some parts with ASA. But now we know also the behavior of 3DLac spray.
    Not recommended!
     
  • Geerts salt method 
    Not tried, but I guess it could be similar to just cleaned glass because the salt will not help to get less adhesion. But I want to try it sometime and will then update the list here with the results.

 

The verdict

I will do my future Tough PLA prints with a thick layer of glue. Maybe I should try Elmers wood glue mix or PVA slurry, could be easier to apply, than painting the glass with the glue stick. Basically, I can say you don't need any helpers for adhesion, but you definitely need something to get your part off again from the glass. The advantage of the glue is, that if it persistently will not come off the glass you can use some water around the part or even watering the whole glass until the glue gets soft enough. I haven't tried to put the glass into the freezer, which could also help.

 

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Strange, my tough pla parts with 3Dlac are lose on the plate after cooling down. On the 3 and the 5 same behaviour. Mostly i use the default settings with the new beta version. What can be different?

 

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Good question! Maybe it has something to do with the model, I usually print with ToughPLA. Just 15mm high, so no possibilities to grab the part and the support structure on the bottom is maybe also not helpful. But the outer frame sticks so well to the glass, that it is impossible to get in with a spatula. So I always begin from the inner side with the spatula and try to lift it there.

 

1656774965_Bildschirmfoto2019-01-18um19_49_38.thumb.png.540306cced82fab69a4ae89aa40ada06.png

 

170401909_Bildschirmfoto2019-01-18um19_50_01.thumb.png.b46b3184e2ce5a84c53af7add9b951f2.png

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Well, i don't even have to do a thing, all my pieces are virtualy lose on the plate. And i also have elephant foot, so i suppose my first layer is squished enough. Things change when i use breakaway or pva, the the parts stocks more, mostly thrue the second material.

What i do is use 2 glass plates, to let the part cool down naturaly until it pops.

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Very strange, a little difference ok, but the opposite? But on the UM3 I never had a problem, and everything comes off easily. But maybe it is the batch of the material. I should print the part also on the UM3 with the same spool to see what happens.

 

For the S5 I currently have only one glass, but it had time for 7 hours to cool down, so that was not the issue. If I would have enough free space in the freezer, this would help probably, but no chance currently. But I could put the glass outside, it is getting colder here again.

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That would be great, many thanks!

But I think it makes only sense if you print the same part, but you can abort after 2-3 mm, then we know if it is the support structure or something else.

 

HUE_Frame.stl

Just use the normal 0.15 profile, and enable support.

 

Thanks a lot!

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On 1/18/2019 at 8:22 PM, Smithy said:

That would be great, many thanks!

But I think it makes only sense if you print the same part, but you can abort after 2-3 mm, then we know if it is the support structure or something else.

 

HUE_Frame.stl

Just use the normal 0.15 profile, and enable support.

 

Thanks a lot!

Testing right now!

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7 hours ago, Smithy said:

Thanks!

Smithy, print finished at 14:40, and it cooled down until 18:00, so certainly cold.

Tough pla  .15mm, support from extruder1, 10% infill.

SUPRISE (for me anyway)

It was very hard to remove, i had to force my heavy scraper under the corner and had to apply a lot force. First time i encounter this on my UM5 with tough play. If i had to save the part, i would try with water first. (this is my favorite for critical parts that stick to well)

So, seems that the form also has influence? And if so, i would expect it to be because the support is very large in the x and y, but very low on the z.

Greetings,

Rudy

  • Thanks 1

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Thanks again for testing Rudy, I really appreciate it.
I'm glad it's the same with you because I thought it was just me. I also think it's because of the support below, it's a bit unusual and in combination with the frame. I suspect the support structure prevents the stress from cooling down, releasing the part from the glass. Lately, I've almost only printed these frames, about 50 pieces with Tough PLA. Probably there will be no problems with "normal" parts. But I am finished now with this project, I have processed the last order over the weekend, and can now concentrated again to other things.

 

BTW: This frame is to cover the traditional light switch when using a Philips HUE dimmer switch.

IMG_0519.thumb.jpeg.67e6e15ca306371e80209465bc13af2d.jpeg

 

IMG_0521.thumb.jpeg.fdcae0ce4b3a6fe3a4ffa1aaba7328d7.jpeg

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3 minutes ago, Smithy said:

Thanks again for testing Rudy, I really appreciate it.
I'm glad it's the same with you because I thought it was just me. I also think it's because of the support below, it's a bit unusual and in combination with the frame. I suspect the support structure prevents the stress from cooling down, releasing the part from the glass. Lately, I've almost only printed these frames, about 50 pieces with Tough PLA. Probably there will be no problems with "normal" parts. But I am finished now with this project, I have processed the last order over the weekend, and can now concentrated again to other things.

 

BTW: This frame is to cover the traditional light switch when using a Philips HUE dimmer switch.

IMG_0519.thumb.jpeg.67e6e15ca306371e80209465bc13af2d.jpeg

 

IMG_0521.thumb.jpeg.fdcae0ce4b3a6fe3a4ffa1aaba7328d7.jpeg

 

3 minutes ago, Smithy said:

Thanks again for testing Rudy, I really appreciate it.
I'm glad it's the same with you because I thought it was just me. I also think it's because of the support below, it's a bit unusual and in combination with the frame. I suspect the support structure prevents the stress from cooling down, releasing the part from the glass. Lately, I've almost only printed these frames, about 50 pieces with Tough PLA. Probably there will be no problems with "normal" parts. But I am finished now with this project, I have processed the last order over the weekend, and can now concentrated again to other things.

 

BTW: This frame is to cover the traditional light switch when using a Philips HUE dimmer switch.

IMG_0519.thumb.jpeg.67e6e15ca306371e80209465bc13af2d.jpeg

 

IMG_0521.thumb.jpeg.fdcae0ce4b3a6fe3a4ffa1aaba7328d7.jpeg

Glad i could help;-)

 

 

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Bonding to the glass is influenced a lot by the weather and by moisture also. So, how is your environment currently?

 

Before I found the salt method a couple of years ago, I used to print on bare glass. On cold freezing winter days when the air was very dry and there was a lot of static electricity, I got good bonding. But on moist, rainy days, I got no bonding at all: the filament would curl up immediately. All this with standard Ultimaker PLA and colorFabb PLA/PHA, and with identical models and settings, and identical gcode-files. This huge variation was very frustrating.

 

Also cleaning the glass played a role: when cleaning with window cleaners or dish washers, I got no bonding. When cleaning with pure warm tap water only, I got reasonable bonding (on cold days). We have so-called "hard" tap water here, very calcium-rich.

 

The salt method seems to smooth things out: for me it gives a good bonding when the glass is hot (even on moist days), but no bonding at all when cold, so models come off by themself after cooling down. This is the big advantage for me: easy and fast to apply, and easy to remove: no mess, no need to remove the glass.

 

I am still not sure why it works, from a chemical or physical viewpoint? I guess it has to do with modifying the surface-tension of the glass: higher surface-tension gives better bonding, lower tension (like after treatment with oil or soap) gives a worse bonding. But this is a guess. Maybe it also has to do with the chemical composition of PLA, if some parts of the molecules would have a polar charge and are attracted to salt, which is also polar  (Na+ Cl-) ? Again, just guessing.

 

On ABS the salt method does not work. On PET it does not improve bonding, but it seems to make removal easier after cooling down: here it looks like it breaks the bond between PET and glass? Also not sure why that is.

 

It does not work as good as dilluted wood glue for very narrow but tall models, like lantern poles, or for models with huge overhangs that curl up, or for models that take very long to complete. It seems wood glue can absorb shocks and vibrations better than salt (not surprisingly). So it works best for low and wide models that can be completed in a few hours, like mine (see pic below).

 

If you try it for Tough PLA, I am curious about the results and I would welcome feedback. Chances are it makes removal easier. But bonding during printing probably won't be as strong as dilluted wood glue or 3D-LAC.

 

ostroncp_cutout1.thumb.jpg.60e7c999bc0d7ff65fe245ac679b4dcb.jpg

 

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Thanks, Geert for pointing this out. Yes, you are right, I didn't think about weather conditions and humidity. I have round about 22° C and 40% humidity currently.

 

I will give the salt method a try next time I print with ToughPLA and come back with the results.

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