Upward curling corners / sides?

Upward curling cornerns / sides?

I'm printing with a Replicator 1 Dual, and so far prints are pretty good, but I have an issue which I cannot explain.
When I observe the printing process, I see that the corners (eg. in my example the 50mm tower calibration tower) curn upwards, as if maybe the nozzle is pulling it up or maybe something else is causing it, I don't know.

See the pictures for illustration. There are pictures of the 50mm tower during printing, the half finished print, the precision block and also showing a tower model where you see that the corners curl up somehow. This is not the Z layer change artifact as it is visible not only on one corner.

I have tried playing around with the following, to no avail (same issue of corner curling):
1. Decreased the temperature from 225 to 215
2. Decreased the HBP temperature from 110 to 90
3. Print at lower speeds (original feedrate was 80, using Sailfish), at 40mm/sec
4. Decreased the maximum Z speed to 16mm/sec (not sure if Print O Matic overrides this)

Skeinforge using Print O Matic with some overrides:
- 10%
- 0.27mm
- 1 shells

I'm using a yellow 1.75mm ABS filament.

Any ideas?

Thanks!
Bence

Looks like you're extruding too much plastic. I've forgotten how to adjust this in Skeinforge. After you've done E steps/mm calibration for the firmware, there is an extrusion multiplier that is basically a fudge factor for whatever it is that causes the calculated flow rate to be different from what's deposited.

I'm currently using Slic3r, which is much easier to use than Skeinforge (and enormously faster). Trying KISSlicer and cura are on my to-do list.

Indeed, it was partly too much extrusion related. I have adjusted the Print O Matic setting of filament diameter as a fudge factor, then it was better. And actually it turned out that also the HBP temperature was still to high, but with 90 it worked quite well.

Thanks for your tip!