ABS printing issue

Hi,

I usually print with PLA. I tried ABS a few times but the print never turned out as good as the pla ones.

Today I tried it again with a new ABS filament. I had no warping, which was the problem in former prints.
Now I have a new problem. the print looks very good for most of the layers.

But in last few layers of the print the model has a small tower and the ABS downwards the actual printed layer did not cool done. So the whole tower moved with the nozzle.

What is the problem? I think using a cooling-system is not the right way for ABS.

For this print I use a Prusa i3 with a e3d Hotend. No modelcooling. 220°C.

The problem is that the area is very small so the hot extruder keeps depositing hot plastic on top of hot plastic. Print a sacrificial cylinder alongside your object to give the extruder something else to do while the last object layer cools and solidifies.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Agreed. I print a small tower next to my print to increase the print time per layer. OR just print more than once piece at a time.

Thanks!
Is it common to use sacrificial towers when printing with ABS?

I also know sacrificial towers when printing with something like the Diamond hotend to wipe colors.

Yes, common. You don't want to turn on a print cooling fan because it will cause other parts of the print to delaminate. You have to give the plastic time to cool and solidify. You just move the extruder away from the print for a while, but it will probably ooze filament so when it goes back to the print it will deposit a blob of plastic and look ugly. Giving the extruder something to do prevents ooze from messing up the main print.

You can print multiple parts and separate them on the bed so it takes a while for the extruder to move between them.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thank you all!

I did a calibration print with ABS and recognized another problem (see picture attached). The edges at layers that are near the heated bed bend inside.

What could cause this? The bed temperature is 100°C.

That's "elephant footing". The bed is too hot. Start with the bed hot for the first layer to help print adhesion, then drop the temperature. The bed may not cool quickly enough to prevent this problem in a quick, single-walled test print, especially if you have thermal insulation on the underside of the print bed which helps weak heaters to get the bed up to print temperature, but also slows down the cooling of the bed when you drop the temperature or when the print finishes.

If you're printing PLA turn on the print cooling fan after the first or second layer.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks so much, that helps a lot.

Which temperaturdrop would you recommend? Even if you can't tell it for all printers and I have to find it out by myself, but which is the right direction? From 100°C to 90 or 80?

Should I also drop the first layer bed temperature?

And yes I have a thick thermal insulation on the underside of the bed.