Hollow cube is leaning but infilled one isn't

I have a Prusa i3 and after some jamming on my hot end caused by me trying to print 0.4mm layers with a 0.4mm nozzle DOH!!! I decided to print out a hollow 20mm cube with 1 perimeter, no infill and no top to calibrate the extrusion multiplier - something I'd never done before.

The resulting print was a nice hollow cube with the top, bottom and sides (on the x-axis) perfectly parallel but leaning forwards such that the top was about 5mm in front of the bottom. Multiple reslices and checks later (including updating the marlin firmware) still no improvement.

Time to check the trueness of the frame (I'd not done this first as I've got it tucked in a box in the corner of the garage so it was not a trivial exercise. With the kind of lean I was seeing over 20mm it would have been pretty damn obvious the Y/Z rails were not perpendicular (about 9 cm at the top by my back of the fag packet calcs) Anyway it was about as square as I could make it so I was a little bit stumped.

I tried downgrading the firmware to my previous build, still no change. I measured the position of the bed on the y-axis at the bottom of the print and then again at the top and sure enough it was in a physically different place which just reconfirmed that it wasn't the squareness of the frame. I tried swapping the x and y axis stepper drivers incase one was on the fritz but that didn't help either. I suppose I could have tried swapping the motors too but that was even more time consuming so in an act of desperation I resliced but with 25% infill (no other changes to the profile) and reprinted ...

And guess what ... a damn perfect cube in every dimension.

One of the first things I'd checked was the produced g-code and it was giving the same starting x and y coordinate for every layer. So can someone please help. Why is it doing this ? and how can I make it stop ?

(Oh and I've been using slic3r version 1.1.7)

Edited 1 time(s). Last edit at 01/07/2015 12:02PM by BarneyG.

It sounds like the hollow cube isn't allowing enough time for the plastic to set up between layers. Use the settings to slow down fast layers and/or activate a part fan, if you're so equipped.

It is already going very slow and the fan is active ... the thing is the bed is physically moving to different y locations on higher levels despite the code telling it to go to the same place.

I've since tried a hollow cube with 2 shells and it also doesn't lean like the one with infill ... so the problem only seems to exist on the single shell hollow cube.

Edited 1 time(s). Last edit at 01/08/2015 09:52AM by BarneyG.

looks like at least someone else has seen the same issue :

[github.com]

Unfortunately it is marked as closed ... I've raised it again.