I’m having an odd failure of extrusion on a print (see photos). There are two of these locating pins on the top of the model and they’ve failed because filament (PLA) stopped extruding. On inspection, the hobbed gear was choked and the filament had the usual gouge in it, but why did it happen right at that point? This was a 12 hour print, and these two pins probably only take 10 minutes of that time right at the end (they’re the highest point). This isn’t a one off either, this has happened twice now, with the failure at exactly the same point.
So the question is, why is the extruder perfectly happy for 11 hours 50 minutes, producing a perfect print, then clogging in the last 10 minutes on these pins? I was wondering if it is something to do with retraction, maybe switching between the pins (which are quite small, maybe 4mm diameter) is causing too much back and forth on the filament while extruding very little? The printer (Original Prusa i3 Mk2), quite happily prints detail far finer than this normally.
Any ideas? I’ve another print going right now, and there’s 10 hours left before we reach this point. At the moment the hobbed gear is perfectly clean.
Hi folks, well, I think @wirlybird was on the money asking about the temperature; this print was “standard” PLA which, from my supplier on this printer, I print at 205C, but I’d accidentally used a profile for PLA+, which prints at 220C, way too hot for that filament, so I suspect there was some “heat creep” and the filament up by the hobbed gear was getting too soft. It doesn’t really explain why the rest of the print worked OK, possibly because of a higher throughput during the main body, but I watched the pins being printed last night and there is a lot of shuffling to and fro, so maybe that, combined with filament that had got soft, was the cause.
Whatever the reason, the last print came out perfectly (when set at 205C), right down to the slightly domed top of the pins and the hobbed gear remained clear.
@Perry_1 it being PLA, and a 50 micron, high detail print at that, the profile is already using 100% fan so if it had been cooling, I’d have been a bit stuck It’s hard to tell from the photos but the pins weren’t melted they simply weren’t printed at all; the mess is what remains of half-extruded perimeters and infill rather than overheated blobs.
So glad to hear its been fixed. I was going to try to jump in and print your model (just the top part) on my printer to see if I could figure it out! I was just imagining you needed these 10 hour prints, and the fact a tiny part on top was preventing the print job from being completed was making me lose sleep!!!
