Fixing Warping with ABS

[idan]

Hi all,

Not sure which forum to post this in, but I have a Rostock Max v2 which I'm still working on tweaking the settings. I don't have a heated chamber yet, though I put a large cardboard box around the machine when it's running to try and keep breezes out.

I'm trying to print the new guitar posted on Thingiverse (http://www.thingiverse.com/thing:486731), and my last two attempts have had significant warping that makes the result unusable. I understand ABS prints best with a heated enclosure, however this isn't a particularly tall item, though the bottom is solid which might make the the shrinking more prominent.

I took some pictures here http://imgur.com/a/GspEN

The other things I can think of are:
* This is the first item that I've printed at 0.4mm layer height (stock hot end + nozzle), and I might be simply printing too fast / too cold (I can't seem to get my hotend to go above 235C due to the current PID parameters)
* The heated bed starts off at 90C and I lower it to around 80-84C after a few layers.
* The head starts off at 220C, and I increase it to 225-230ish during the print
* I was previously over extruding due to the e-steps calibration, I think I have it dialed in but I might be a bit low (calibrated by trying to feed 300mm of filament with marks on it, the error due to the marks should be +/- 1-2%).

Anybody have any tips on how to print this without having to build a heated enclosure? I was able to print the ukulele design by the same author with minimal warping (fixable by just filling in with super glue) though at 0.2mm and using Slic3r at a slower print speed. It is a much taller design though.

I'm using Cura (via Repetier-Host) at a 35% infill.

Thanks!

[Renha]

PEI sheet + copper/aluminium plate + 24V power supply

Search forum for that things, I have all af them and now i haven't warping issue, without heated enclosure or speed/extrusion calibrations