Cura Bug: Random Solid Layer in Hollow Cylinders

[matt-gajkowski 0]

So, I've been printing a number of hollow cylindrical objects, and for a while now too, so I've experienced this problem in 13.12 and the version previous to that. It happens almost every time and I just haven't come forth because I thought the new version would fix it.

So anyway, here's what happens:

Looking at image 4 you can see there is a 'floor', which Cura handles just fine (as in image 1), and then it goes up vertically before opening up into a toroid. In image 2 you can see how Cura creates a solid layer (just one layer thick) throughout the entire inside instead of just the ledge area.

Now, it would seem that something about that ledge 'tripped' Cura into doing this, but I have printed other objects such as a short pipe with spirals on the inside, and out of nowhere special it will make a solid layer. Sometimes this even happens twice. And this sort of thing happens to almost every hollow cylinder I make.

For the time being I just remove this oddball layer with a hobby knife, but if there's any way to fix this I'd really appreciate it!

Link to this particular STL below:

http://www.filedropper.com/base-outertoleranced

 

[Daid 306]

It happens with high polygon models if Fix horrible type A is enabled (in the expert menu) this has been made default which makes this bug pop up. I've fixed it for a next release. Workaround is to turn the fix horrible type A off.

 

[nick-foley 5]

This happens to me all the time, and it has no relation to the "Fix Horrible - Type A" setting. It even happens on STLs with relatively low poly counts. Nothing shows up in X-ray or other modeling programs. Sometimes it adds a full layer, sometimes it adds a random portion of infill.

Screenshot of problem:

https://www.dropbox.com/s/00d4kr3cpx2hivv/Capture.JPG

Link to STL:

http://www.thingiverse.com/thing:208346