Bed adhesion issues

I have run some tests with PLA on my new thermistor-controlled heated bed, and find my sweetspot is 48C. At 45C the build surface has to be spotless, and tall objects can be knocked off on rare occasions. At 50C the pieces stick so good to the plate I can't remove them without damaging the parts. For larger or difficult prints I really don't want to mess up, I still print at 50C and lower the temp to get the parts off when I'm done. But at 48C I can pick off finished parts without too much force, and I don't have to bother with changing temperatures. If I go any higher the first layers of the prints deform.

Again, my heater is simply a ladder of parallel wired nichrome, taped with kapton to the bottom of a dibond FR plate. Under it's insulated with kapton and a piece of sound dampening mat used in cars (one side sticky, foam core and reflective foil on other side), and it's bolted to a piece of mdf floor board I use to screw the lm8uu holders to. On top I have a 4mm regular window glass plate secured with binder clips, which I print directly on. The thermistor is secured with kapton under the bed, between two steps of the nichrome ladder, so the top glass surface temp is probably a little off. The total resistance of the ladder is 1.2Ohm, and it heats up very fast.

I clean the glass with acetone when it gets greasy from fingerprints. If I manage to keep my fingers away I don't have to do it very often at all, perhaps once every day or two if I print constantly.

As others have said, I find room temperature can be a source of problems, as the top build surface is a bit colder. This was most evident with my old heater which I just ran straight off a cheap 12-24v brick supply, and never reached more than 40-45C. But with the temperature controlled bed running from a more adept power supply I have not run into problems, so far.

Sorry for repeating myself, but my bottom line is, I really don't understand why some have so much trouble getting PLA to stick to heated glass? I can't see what I do different, and I seriously can't get the prints off without manhandling them when I print at 50C!

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-Nudel
Blog with RepRap Comic

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Nudel
build surface has to be spotless, and tall objects can be knocked off on rare occasions. At 50C the pieces stick so good to the plate I can't remove them without damaging the parts. For larger or difficult prints I really don't want to mess up, I still print at 50C and lower the temp to get the parts off when I'm done. But at 48C I can pick off finished parts without too much force, and I don't have to bother with changing temperatures. If I go any higher the first layers of the prints deform.

I never had a problem removing printed parts in PLA from heated glass. Just remove the glass from the heated bed and let it cool and the parts come off on its own just as Adrian showed on his video. I have multiple glass plates so that I can start heating for the next batch as soon as I remove the finished one.

The problem may be the filament brand. Where are you all located? Who manufactured your filament? What resin is it made of? They may even use different additives while colouring the natural resin.

Natureworks Ingeo alone has 7 lines of PLA and 27 different resins.
Cereplast sells PLA resin that is a hybrid of Natureworks Ingeo and their own resins.

I am in Canada and get my filament from Ultimachine. Its Natureworks Ingeo 4043D resin with whatever added by the extrusion company while colouring and extruding.

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brnrd Wrote:
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> I never had a problem removing printed parts in
> PLA from heated glass. Just remove the glass from
> the heated bed and let it cool and the parts come
> off on its own just as Adrian showed on his video.
> I have multiple glass plates so that I can start
> heating for the next batch as soon as I remove the
> finished one.

Yes, if the glass cools they snap off without effort. But I'm lazy and prefer to just snap the print off and start the next one, without having to change the build plate and/or wait for temperature drop. When doing full build plates I can see the value, but as of now I prefer as fast and effortless printing as possible. ;-)

Sublime Wrote:
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> The problem may be the filament brand. Where are
> you all located? Who manufactured your filament?
> What resin is it made of? They may even use
> different additives while colouring the natural
> resin.

The last test where I settled on 48C was done with chinese PLA i bought through an ebay seller in europe. I don't know the details of it, but it's slightly transparent an very smooth to the touch, I extrude it as low as 160C. It's (as far as I can tell) the same stuff they sell at supply3dpla.com

I have also printed about 5-10kg of various color Ultimachine PLA @180-200C on heated glass @~40-45C, and it works just as well, as far as I can tell.

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-Nudel
Blog with RepRap Comic

I usually clean surface with acetone. One day i noticed i had a sticking issue. Some time back i changed to another acetone. Looking at the new bottle showed up that it was not only acetone with water. It was actually acetone meant for women fingernails paint remover, and as such, it also contained some other components, like liquid paraffin - which is some sort of wax, and few other stuff meant i think as skin and fingernail nutrient. At first it didnt made a difference in small quantities but as the wax sticks to itself i guess to each application i was contributing to adding more and more wax, until it showed up as an critical issue. I pay more attention since then at the labels, and only use the stuff that has only acetone and water in it and nothing else. No clue if that is the case here, but might worth mentioning and maybe investigated.

Edited 1 time(s). Last edit at 10/30/2011 01:37PM by NoobMan.

Good catch, I can imagen how something like that could be easly overlooked, I'd expect a thin layer of wax to cause a huge difference to stickyness. (or lack thereof)

I have given a try to electrical tape and it is working now ok even for large prints. I am not sure for how long though.

misan

They haven't last longer. You should use 3m adhesive tapes instead of it.

Absolutely, and what is worse is that electrical tape adhesive will loose grip when heated material is layed on top, so large parts will warp easily.

I can only recommend this for printing a small part on a cold bed when you have run out of other choices.

Haha, this is great, a thread necromancer came along, and then misan, the original last poster of almost 3 years ago, immediately replies

Anyway, to add, I have great hopes in a PEI surface (PolyEtherImide) and am currently looking what is the best way for me to obtain an affordable place of PEI.

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Ohmarinus
Haha, this is great, a thread necromancer came along, and then misan, the original last poster of almost 3 years ago, immediately replies

Anyway, to add, I have great hopes in a PEI surface (PolyEtherImide) and am currently looking what is the best way for me to obtain an affordable place of PEI.

There are many kinds of PEI and from what I have read, the kind that works best is not easily found in small quantities. But you might check this plate out instead. You can print PLA easily with no heat and some users find they can print small ABS parts without heat as well.

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Wayne
PRINTinZ.com

I've printed PLA on glass, glass with kapton, and ABS on kapton with ABS paste.

PLA on glass works perfectly - 60 degrees. Never clean the glass with nail varnish remover. I learnt the hard way - it has oils in it.

I now print on Kapton on glass purely because I previously printed ABS on it so it was easier to leave on. I get great adhesion, easy removal, and I just give it a quick squirt of isopropryl occasionally, but generally I just wipe it dry with kitchen towel between prints to remove any dust.

The key factors are the 1st layer - consistent and the right amount of squish. If I'm printing something very thin I add a 2mm brim to the print.

When I didn't have auto bed levelling, I had adhesion issues when the bed wasn't perfectly level. Auto bed levelling has made the process pretty much click and print!

I printed a huge item the other day and one corner just insisted on lifting, even when I rotated the print. Was odd. Never figured it out.

I find wiping the glass with balsamic vinegar works well. Also lemon juice.