RE: Mini (New: Shipped Dec 16 2020) - PLA feed & printing issues
Further to previous, and what I think will be my last update to this thread;
I swapped back to the factory installed PTFE, which was now 42.5mm. Refitted everything back together after cleaning, ensuring a nice snug fit for the PTFE liner in the heat break.
I had flow, great. 1st Layer calibration completion gave me some hope.
I noted that the gearing started clacking after the first few layers, when the Prusa slicer set the nozzle temp to drop from 215 to 210°C.
Manual over-ride to bring temps back up to 215 seemed to address it temporarily.
Not too long after, the clacking from the extruder gears started up again, so I adjusted tension.
I managed to get 1 little L shaped clip (35x25 x 28mm high) printed (circa 1hr job, 0.16 layers)
The quality was quite poor for a brand new machine, and it was the weakest I'd ever seen off any 3D printer.
I tried to up this to 6 impressions of same clip, which was a 4hr+ job.
I couldn't get beyond the first layers. Filament is not flowing consistently, and not at all when the highest output speeds for this job are met on infill (65mm/s).
The installation of a modified heat break may solve some issues, but the filament gearing/tensioning/traction is absolutely hopeless. Given this is all built around the bespoke XZ junction, I'm not getting involved in addressing what is either a design or manufacturing fault.
If this is what passes for QA, then I have no confidence in the product, sorry.
I'm deeming the unit as unfit for purpose and will be arranging a return.
RE: Mini (New: Shipped Dec 16 2020) - PLA feed & printing issues
@andrewa
I pretty much had all the same issues after I tried to clean the heat-break and put it back together as-is - after that first clog and a bunch of cold-pulls it was never right. It would do the first few layers, then was a mess again. That included taking the extruder apart completely and cleaning it out. With that old heat break I was always seeing bits of filament in the extruder window.
I've got the new bondtech one in there now, with a new nozzle b/c I didn't trust anything in the hotend after the clogging problems - and I have noticed the extruder behaves a lot better - no signs of bits and pieces. The overall feed of filament just seems a lot smoother, consistent, etc - but I will admit this heatbreak isn't the magic bullet either. I'm having a lot of issues with print consistency that I haven't quite figured out yet. Issues I didn't have before with the stock parts (when it worked)
I've mentioned the issues to a friend with a MK3S+ and he said he's just basically plugged his printer in and printed and has never had to fuss with anything like this.
RE: Mini (New: Shipped Dec 16 2020) - PLA feed & printing issues
I just fixed this problem on my Mini. I have it about 9 months. In the beginning prints wwas great. About a month ago quality of PLA prints dropped down - very rough wall surfaces, not homoenous filament supply. Ugly. But ABS prints are still great. Finally it stopped to suply filament, and just clacking. Tested more types of PLA filament, one was OK, next 4 problems. ABS great. Disassembled hotend. 3 problems found.
1. A lot of dust behind fan on heatbreak - efficiency must be significantly lowered. Cleaned.
2. PTFE tube ends deformed, notch up to 1 mm, probably gap and grinded by filament. Changed PTFE tube. Lenght is not so important, adjusted position of tube, upper nut tightened 120 deg.
3. At cleaning of hole for PTFE tube by 4 mm diameter drill noted not smooth turning. Difficult to recognoize, but it looks that bottom - where PTFE tube should have to fit tight -is not flat surface, conus. Instead there are notches. Then PTFE tube will never fit tight, always there will be gaps. This can be problem even on new printer. Tried to drill-smooth it as much as possible. Best would be to fix it on turning machine. After assembly I have again first test prints OK, problem solved. Then change to Bondtech as solution give sense. But probably it will be possible to fix it just with battery hand drill and 4 mm drill