The curse of ABS (Warping)

[Keith]

Indeed Tom is right, I never use a fan on ABS and it certainly helps the lifting situation. Another method I use which combined with not using a fan is a small fan heater, it doesn't need to be an infra red heater just one of the cheap ones, in England B&Q sell them for about 5 or 6 GBP so they don't hurt the budget and the saving on material pays for the heater in the long run.

[RP Iron Man]

You mean that the weight of the part squishes the bottom layers?

Above it's glass transition temperature (Tg) of about 105C, ABS takes on a soft, rubbery consistency and consequently is very susceptible to deformation. When you have the bed temperature hot enough, the bottom layers of the part rise above the Tg of ABS and become soft and rubbery. As a result, the weight of the part is enough to slowly squish/deform the bottom layers.

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Hi Eric,

Do you use kapton tape or do you print directly to the glass?
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No, a while ago I experimented with several different bed setups for ABS printing and I found that I had the most success with glue stick (Elmer's, UHU, etc..) applied to glass.

I found that kapton stuck well, but the part often lifted the tape right off the glass bed, and parts were very hard to remove without damaging the kapton.

I have never had success printing on heated glass, no matter how carefully I cleaned the glass or how hot I set the heat bed. I tried ABS glue on glass as well, but it never really worked consistently and was a real PITA.

Here is my complete printing set up for ABS printing on my Prusa I2:

- 2 smooth, even layers of Elmer's glue stick applied to glass surface (allow each layer to dry before applying the next). Reapply every 48 hours of printing or as you see fit (adhesion of glue stick starts to wear out after a while). You can just apply the layers on top of each other until the surface starts to get messy, at which point you can easily wash the layers of old glue stick off with water.
- First layer bed temp = 120 though you could get away with less.
- Other layers bed temp = 80C for large parts, but you can raise this to 90C or even 100C if you are having trouble with tall skinny parts lifting off the bed.
- Wrap clear plastic garbage bag around your print area to trap in the heat from the heat bed (at 90C bed temp I can get to about 40C chamber temp)
- Put a fan blowing over your extruder motor as it will get hot.
- Enjoy your warp-free prints!

Eric

[Black_sheep]

Thanks for sharing your recipe for warp-free ABS print Eric

As for the kapton goes I had roughly the same problems when I tried to print ABS, even cooling the bed down to room temperature didn't prevent excessive attachment and damage to the tape.

Anyways I am running my machines inside the flat and I got too much complaints from my family about the smell of ABS so I quit using it quite soon. PLA is my absolute favorite although ABS is very useful for tall thin parts

- Filip

[RP Iron Man]

Thanks for sharing your recipe for warp-free ABS print Eric

As for the kapton goes I had roughly the same problems when I tried to print ABS, even cooling the bed down to room temperature didn't prevent excessive attachment and damage to the tape.

Anyways I am running my machines inside the flat and I got too much complaints from my family about the smell of ABS so I quit using it quite soon. PLA is my absolute favorite although ABS is very useful for tall thin parts

- Filip

BTW, I forgot to mention, the parts usually pop off by themselves once the bed has cooled to about 50C. You should hear some cracking noises as this happens. You can use a fan to speed up the cooling after the print is done, but only if you are using a borosilicate or tempered glass surface. Ordinary thin window glass is more sensitive to temperature fluctuations, so it could crack if you try to cool it too quickly.

In either case, you will never have to pry the parts off the bed again

Eric

[jimc]

i pretty much print exclusively with abs. the next thing on my list is to make the box for the printer but with the few things i have done, i have made a big improvement and i dont have any issues with abs unless i am doing something really big with thin walls like a box. #1 like ironman said the cooler bed temp works better than higher. on my printer i have found 90-95deg to be the spot. another thing i have found is with a glass build platform there was a big variance in temp at different points on the bed. the center may be 95 but at the corners it could be as little as 72deg. i ditched the glass and got a 1/4" thick piece of mic6 aluminum. now there is only a 1deg difference across the whole platform. a very even heat. always run the extruder tamp as low as you possibly can while still getting good layer bonding. this will vary with filament used. i always print on kapton with abs glue. i recently glass beaded one side of my mic6 for better adhesion so i am going to do some testing soon to see if i can eliminate the kapton. i dont have any issue with it but if i can eliminate that step it would be nice. if you have a large piece where the corners tend to lift then model some mouse ears onto the corners. they work wonders.

[JohnA136]

We use our Prusas for PLA and our MBs for ABS since they are enclosed. We have been printing with the ABS slurry on Kapton Tape. The Heated bed is usually set at 110 degrees. If I am doing a Demo or in a big hurry, a quick blast from an inverted air duster makes them pop right off. This has worked well for us on our ABS machines, your mileage may vary!

[Keith]

First point, I'm wondering why there are so many variances between machines running the same products, I use Kapton when printing with ABS and find that I can pull off the finished print with my fingers more or less within a minute of the job finishing, it pops off easily but has adhered to the kapton throughout the print. There are others using the same set up who struggle like crazy to get the print off and yet others who cannot even get the print to hold whilst printing, anyone know why?

Second point, I'm looking at other ways of adhesion to save the cost of Kapton, there is mention of Elmers, now my wife is American, I'm English (not British by the way, my wife understands the reasons why now I've explained to her ) and she tells me that Elmers is used by kids in primary school but she's not able to tell me what the comparison is over here. I imagine it's a gentle waterbased glue so it could be something like PVA glue otherwise known as wood glue that joiners and cabinet makers use. Would I be right in saying this ?

[skew]

Keith, Elmers glue is also called white glue. Its also used as a food substitute in the U.S. for elementary kids they love eating it for some reason. LOL

[JohnA136]

I think the big difference in adhesion to Kapton tape is how close the nozzle is to the heated print bed. if you have it the first layer squished on real good, it will practically never pull up and warp during the build, but is harder to get off when done. It is is just laid on for the first layer, it comes off easily but will probably pop off on a larger/longer print. There is a little finesse needed to get it "just right". On my Cupcakes, I adjust the first layer height on the run.

[Mysli]

Luigi, you might wanna try and sand down you kapton as described in my solidoodle upgrade thread.
After i did so myself i can actually lift the whole printer in small prints... thats how good it works for me