Slicer randomly prints a layer with huge perimiter which causes splitting

So whenever I print a larger object (ramps box, or wade extruder size), about 10 or so layers into the print, it starts printing a huge perimiter, larger than what I set, and it ends up warping and ruining the rest of the print. I have slicer set to print at least 3 perimiters, but this one is about 9 or so layers wide.


Sorry if this is a noob question, because this is my first 3d Printer. Here is some information about it:
i3 Box version
ramps 1.4
marlin
mk2 heatbed
j head with .5mm nozzle (I measured it and its more like .62)
1.75mm filament
greg wade extruder

I was messing around with the perimiters a bit because all of the holes I would print turned out too small. This seems to be a common problem. Even with the perimiter size set to .3, the holes are way too small!


Anyway, I have also had many other printing problems, most of which I solved myself, but a few still remain. and I don't know weather I should post them all here or in separate posts.

One issue was with printing gears. I don't really have a problem with corner lift, but when I print gears, the teeth totally lift up, ruining the print. I know this is due to differences in temperature within the part, but it seems like the plastic in the tips of the teeth expands to about two fold, causing it to curl up. Then sometimes the hotend hits the taller gear tips, scaring the heck out of me. I searched around, and tried printing them with a brim, which did not help. There is no air blowing on the heatbed. Any ideas? If someone has a solution or if someone could recommend me some settings for printing gears, that would be great.

P.S. is there a way to set "carve"in slic3r? Thanks in advance.

There was a bug in Slic3r 0.9.9 causing it to be wery generous with extra parameters, it's fixed in the latest version. But the perimeters alone shouldn't be causing warped prints.

Your perimeter width should always be wider than your nozzle size, if set lower you will be stretching the filament, which contributes to warping.

It sounds like you are printing ABS, the way I fixed my gears was hotter extrusion 240-245 degrees, lower bed temperature on all but the first layers, 95 degrees seems fine for my printer, and lower speed or print more objects at a time.

As for holes, nophead had made a exellent writeup here: [hydraraptor.blogspot.dk]

Thanks ralf. I will try what you suggested tomorrow. I'm a little bit weary about bringing my nozzle temperature to 240 degrees because it is a Chinese J head but I will see what I can do. I will report back soon.

Thank you Thank You Thank you!
I updated slicer,
changed the nozzle temp from 117 to 130, and it printed like a charm.
Oh yea and I am printing in red ABS from Kbell engineering.
I did have to leave my heatbed on the whole time, otherwise the large wade's gear warps itself off of the print bed.
For the small gear, I ran the meachine at 100% speed for the lockscrew holder part, then turned it down to 30% speed once it got to the cogs of the gear. I used the reprapdiscount LCD to change the speed. I couldn't be more happy.

Still working on getting large enough holes tho. I wish there was a setting in slicer that would compensate for the cos(π / n) facetting error. But for now a drill bit solves the problem fine.