Progress on 3D printing for the last 2 weeks has been terrible. I converted from printing with ABS filament to PLA. Nearly every print of any reasonable size (e.g. bigger than a small test cube) has resulted in a jammed extruder. Once it jammed so bad I had to disassemble the entire print head to fix it.
I have easily done 20+ prints trying to get things to work. Finally, I believe I have found the problem. In looking at the filament after the printer jams, it looks like a small plug in the extruder.
Doing research I found a theory that some jams are caused by heat going up the extruder from the hot end to the cool end and causing the filament to melt prematurely. It then solidifies before it makes it to the hot end and causes a plug and the resulting jam.
The solution is to keep the extruder cooler. While watching a print that ended up jamming I also noticed that the heater wasn’t working very hard to keep the appropriate temperature. I turned the fan on high (it was off) and noted the heater had to run at nearly 100% just to keep the hot end at temp. That was a big signal to me that the entire extruder was getting pretty hot.
I ran some tests where I started the fan almost immediately after the print begins (after the perimeter of the object is laid down). In most cases I have been able to get a print without a jam.
Once I had things running smoothly on the little tests, I printed an Arduino case. This is the nicest case so far. Everything is nice and square – using ABS juice on PLA works as well as it does for ABS. There were very few drips/blobs/strings on the print.
I’m designing the case for a new switch on my gate monitor (the reed switch is working poorly). I hope to post that soon.