Quote Originally Posted by Hårball View Post
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