Replace *all* the things!

As mention last time, I had been trying out the UniCoFil filament, first the light blue, then the fast-changing rainbow. All through that, I had trouble with stripping mid-print. I got quite good at cleaning up after a stripping incident, disassembled the heater assembly several times, even swapped out the heatsink as I had been a bit forceful on the inserts. No luck. I was starting to blame the filament, but saw that it was considered a benchmark of quality by some filament testers, so unlikely to be the problem. I also tried pushing some filament through the heatsink and heatbreak after removing the nozzle, found some scrapiness at the heatbreak area, but that's probably just because it's metal rather than PTFE. 

Taking a second look at the removed nozzle, I realized it was badly damaged on the threads. Maybe I had put it in wrong? That would certainly explain the problems. Fortunately, I had bought an entire set of spare parts for the heater assembly, so I was able to swap the nozzle and heater block. That's a lot easier with the e3dv6 than the previous systems, no fiddly wires, just two stiff metal inserts and screws to fasten them. It has now printed for several outs without any issues (jinx!).

Here's a close-up of the nozzle:

Things I learned:

• The spring-wound screw that holds the idler door in should be flush with the left side of the block when filament is in. That is the position of least stripping risk.
• The neat little cover mount I had printed for cleaning the filament made it easier for the filament to break when doing the hot part of a cold pull. It should be unscrewed and moved above where you grab the filament (grab the filament with pliers).
• The screw fastening the heater cartridge needs more force than I can apply with a normal hex wrench, I had to get a proper bit driver.
• Pushing filament out while cooling down for a cold pull ensures that the nozzle is full and so is more likely to bring debris with it out.
• The PTFE tube should be 11 mm over the top of the heatsink when in. It will be just visible in the gear chamber.

In related news, I tried using the "little master spool" designed by DasFilament, but the forces of the filament inwards opens up the locking mechanism, and I got this disaster:

Not what I hoped for. Also, it's even easier with this design to have the filament hop out sideways or get stuck between filament and spool. Need to find or make a better design. There are some promising things on Thingiverse, but right now they have a problem where occasionally - even after the page is fully loaded - the page will blank and go "Something went wrong". Web developers, have you heard of a little thing called "graceful degradation"? You should try it some day, it's delicious.

Stripped again, and out of tubes

I was trying out some semi-transparent blue filament from UniCoFil. The temperature tower had quite a bit of stringing, so I tried with 2mm retraction. That, unfortunately, led to stripping when the next temperature tower got to 195C. Despite trying to help the filament come out, unloading didn't work, so I had to snip the filament and open up the extruder.

TIP: When snipping the filament, do so with as much filament above the PTFE tube as possible, to more easily grab it later.

I disassembled enough to have the heater assembly free and tried a cold pull, but there wasn't enough filament sticking out to get a good grip. So I unscrewed the heatsink (this time the heatbreak didn't follow) and could get the PTFE tube out easily. Not so the filament. I tried heating the tube on the bed and then pulling, but again with not enough to pull on. Eventually I used a small hex wrench to push out out from the other end, which worked.

Then I put the PTFE tube back in the heatsink, which was a mistake. I put it so far in that I couldn't screw the heatsink onto the heatbreak, and I wasn't able to pull it out without destroying it. Fortunately, I had a second one. Need to get more replacements, and maybe just a spare of each part.

Having mounted the heatsink on the heatbreak, I could insert the PTFE tube, but not quite enough, now the end would block the gears. So I took it apart again, pushed the PTFE a bit further in, and then it looked OK from my point of view. Not so from an actual functional point of view, it was high enough to hit the gears still. It needs to be barely visible above the edge of the hole.

I tried to align it better, but it took more squeezing than it really ought to, and one I had it in, the nozzle ended up being too low, possible because I couldn't screw the heatbreak far enough in. I will order a bunch of new tubes and spare other things, take the whole shebang apart, and then try first to install from fresh with a new tube, if that doesn't work then replace the heatsink - I think the black insert inside it has gotten damaged.