Originally shared by Jim Wygralak
So, I recently installed a heated print bed and switched from PLA to ABS. Now all of my prints that are more than a few mm tall seem to take on an hourglass type shape in the first 10mm of height, or so.
Does that mean I have my print bed too hot? I’m running it around 100 C, according to my thermocouple equipped DMM.
And, how do I print tall skinny things? Can I still use a fan with ABS for that type of object?
#3Dprinting
I do believe it’s caused by uneven cooling of the ABS. Or your first layer(s) are to flat. Ambient temp of the room you are printing in has an effect on ABS as well.
I run my bed for ABS at around 120c and my hot end at around 240c.
The tallest object I have had.to.print is the top z motor mount for an i2 and it was a pain due to all the effects stated above.
Start your first layer at a good temp, 100 works for me, then drop it down after the first layer by 5-10 degrees. Your lower layers have too much heat radiating up through them. You can print tall skinny things with abs, you can use a small amount of fan for very tiny sections or tune your temperature and speed to make it work.
You might want to shutdown your fan…
My bed for ABS is nowhere near 100C. I can touch it briefly and not get burned, but too long I will get a very minor burn. I’m still using the old this voltage for these resistors when printing ABS method, so I don’t know the actual temp haha. I use kapton tape on the bed that I sand with 200 grit. I recently found that printing between 0.08 and 0.2 mm gets good adhesion (it probably gets better as you go smaller). At lower heights it is so good that removing the prints is often a challenge. I recently started printing at 0.34 mm to try out Joris mode and while my cups/vases stick well enough to not warp while printing they are very easily removed from the bed.