Help with calibration

I have a Huxley from reprappro and I'm stuck on a strange issue. I'm trying to print the small gear (12 mm) from the new extruder mini that ships with the Huxley. The gear comes out twisted counterclockwise as it appears that each following layer is tiny bit offset to the right. There also appears to be tiny slope of the gear inward.

Also the first few layers appear better spread, starting from the middle up it looks like there is more filament than needed and I guess it could be caused by the slope inward.

The gear looks round from the bottom and I think there is no problem with the belt tensioning. I had to use one 4.75A on 19V power supply, as I had problems with the one supplied from Reprappro, could this be the problem?

I am attaching two screenshots, excuse me for the bad quality.

Perhaps it is skipped bits.
Is it the same if you reduce the printing speed?
Best regards.

Thanks for the reply. I reduced the speeds, but it looks more or less the same. There is still this twisting. I think it is twisted clockwise, because the hotend rotates clockwise and it is sweeping small parts from the previous layer that is not dried out yet. My layers are 0.3mm in height and auto default extrusion width and I have 20% infill. The temperatures are 170/75 C.

I suppose if there was an option to switch directions while printing it would not be twisted, but it would still have this tilt (you can see it on the second picture clearly).

Edit. In fact the problem seems to have been in the temperature (maybe also combined with the speed). I lowered it to 160 degrees and it looks quite straight. However it still has trapezoidal shape with angle around 85 degrees. Has anyone had this problem before?

Edited 1 time(s). Last edit at 04/03/2013 04:20PM by vasko.

I wonder if your axes are out of alignment.
Check that your Z-axis is exactly perpendicular to the X and Y. Its the smooth rods that matter, not the threaded z-rods.

Also, printing just one small part can cause problems, as each layer doesn't get time to cool before the next layer goes on. So the part wobbles. Printing at a lower temp doesn't really help for this.
Try printing two or three copies at once.
A fan helps too.

Hello
Check that there is no backlash between the pulley and the crankshaft.
The pulleys that gave supplied are not the best,
After a while they begin to have backlash.
I suggest you replace them with aluminum sheaves and the tightening screw.
Best regards

Thank you both. As Inquisitor said printing small parts is not the way to do it. I tried using a fan to cool them and the results were a bit better, but it is still better to print several copies in order for the detail to cool down between layers.