Printing resumes

OK, now the Prusa is working once again (with Yellow ABS this time) I immediately began printing the next set of blades for the VAWT project I am working on, again encountering the malformed leading edge issue I had spotted previously.

As it turns out this does not appear to be anything to do with my retraction settings but more to do with trying to print overhangs so close to the hotbed in ABS, the overhang stays soft and is mechanically deformed by the next layer printed resulting in curling on the leading (or trailing) edge, I have tried several different techniques to resolve this issue none successful as yet and I am communicating with Quentin (the VAWT creator) to see if we can resolve this issue, it is very difficult to tell if this is due to the VAWT model needing tweaking so that it is printable in ABS on a hotbed or if it is my particular printer setup that is causing the issue , I will have to investigate overhangs & warping/curling thereof in the wider reprap community to see if anyone has any other suggestions of how I may solve this.

I have already tried

1)     Inverting the blades to see if the problem was only present on the leading edge (it wasn't) but it also showed up on the trailing edge.

2)     Printing several (3) blades next to each other to see if additional layer cool time would help (a very slight improvement but not significantly better)

3)     Lowering the hot end temps and hotbed temps as low as I can get them without the ABS becoming  unstuck, still no significant improvement.

I may have to resort to getting Quentin to add a support structure to the first 1-2cm of the leading/trailing edge (leading or trailing depending on which is overhanging, which in turn depends on which end you are printing the VAWT from)

Other alternatives I will try are to experiment with active cooling, by either changing the hot bed temps (although my previous tests suggest this won’t work) or by force cooling with a fan, (this would most likely work but would also likely cause the part to warp and become detached from the hot bed so not a good solution either)

Alternatively I could switch to PLA which needs a lot less heat (I will try this anyway just to see)

Anyway regardless of the poor print quality I forged ahead with printing the remaining parts of the VAWT after all I can always repair the malformed leading edge with bits of leading edge from other failed prints by hand with a hacksaw & glue!