Trend help angled surfaces

So I’m starting to notice a trend when building overhangs on my taz 5. An angle going up to the left side of the build platform comes out pretty ragged, whereas an angle going up to the right, is really clean. I am using the lulzbot cura settings. What I notice is that that profile runs the part cooling fan on abs, which I thought was something NOT to do.

You are correct, with ABS the last thing you want is the fan for cooling the media on. However the fan for the hotend must be on.

I have only used Cura a few times but there must be a setting for cooling. Just opened Cura and under “Advanced” at the bottom in the left side is a tick box for the cooling fan, just un-tick that box.

So, I’ve been on the line with Lulz, and they said with the heat of the bed, they use cooling with cura profiles to help bridge, and to keep the material from getting too soft. I tried turning the fan off, and I basically got mush.

So, based on this item on thingverse… http://www.thingiverse.com/thing:716002

I’ve added a second fan on the left to see if it solves the crappy surfaces I get with left facing overhangs. I’ve a part running now, so I’ll know more in a day or so.

If it works, I may add a port in that shroud to add extra cooling into the heater block area and see if it solves the heat creep problems I have with PLA, or not. For my use, ABS is preferable for the prototype parts I make.

So I’d like to illustrate the problem I was having, and what has changed with the new fan.

On left hand (home side) overhangs, i had bad looking surfaces like this picture.


I saw the discussion somewhere else about this problem and having to do with the cooling fan being on the right. So, I printed out the thingverse shroud and now my part looks like this.

Side by Side Picture

For those wondering about the raft on the bottom, it’s to eliminate the abalone foot I get with abs and hips on the build plate. Orange built right on build plate, purple built on a raft.

I hope this helps someone, or maybe I can get some guidance as to what’s causing the troubles in the first place.
See this image

And the new shroud and fan mounted

I’ll have to try printing the wing nut. I would have suggested slowing the print speed and maybe a degree or two lower on the extrusion temp. But the print with the second fan looks great!

Thanks, I feel sometimes like I’m chasing little bits. I had a lot of deformation on the bottom of a spoked wheel hub I made until I build my own support parts for the spokes that kept the support material from encasing the hub. I think with larger abs parts, I can turn the fans off.

Now, if anyone knows how to keep the fan off while building a raft I will be happier, as that fan warps the heck out of the first solid layer of the raft like crazy as cura turns the fan on full blast after the first heavy layer.