I actually just got my Polar running. Is your nozzle perfectly centered in the middle of your bed? I had an issue when mine was off that my models came out skewed. Also how did your figure your step per degree for the Y? It has to be correctly figured. What gear ratio are you using for Y and stepper degree?
@deckingman Thank you for taking a look. I reluctantly settled on 5mm retraction. 3mm was sufficient for one of those retraction tests but in practice would still produce really bad stringing. I need to revisit this. For cooling I have the single fan on the front of the heatsink as provided by E3D. I'm not sure how to know if that is providing adequate cooling or not. I'm under the assumption that E3D knows what they are doing when they include that fan (although the connector on their thermistors doesn't inspire confidence). I've been looking out for jams due to filament getting stuck in the heatbreak but none to report (yet).
Printing at 190 gave really bad stringing but 200 eliminated them. 195 might be the sweet spot though. I do have a couple rolls of PETG to try. I've been meaning to see how it works differently anyway.
I totally agree my part cooling is not up to the job. I have a 4010 radial fan, anything bigger is going to be a challenge to fit onto the effector. I've spun my wheels for months trying to find the right way to direct air around such a large heater block. I can't tell if it's the way the air is directed or the total air flow that's at fault. Maybe I should ask E3D what part cooling solution they recommend. To try and combat the overhang with subpar part cooling I've printed as low as 180 and it didn't seem to make a difference. I don't understand why.
Thank you for the effort you put into your blog, it's been invaluable.