End-Of-Filament Change

[KenW]

I had just a couple of metres of filament left loaded, so I wondered whether I could run a print (Tina2S) using up what was left and interrupt the print to load a new reel when required.

Spoiler: it didn't go well, but could have done had I used a different procedure.

What I should have done is splice the new reel onto the end of the old filament before starting the print, then I'm sure it would have been seamless – but I don't have a splicing kit, and a bodge could have jammed in the Bowden tube.

What I Tried To Do & What Happened

I monitored print progress, and the old filament was going to run out shortly after the raft was printed, so it was convenient to "pause print" at the end of the last raft layer. The Tina2S seemed to action the pause at the end of the layer (I don't know whether that was coincidence or by design).

I then pressed "unload filament". Mistake! The hot-end moved up and triggered the Z switch, but nothing else seemed to happen. After a while I decided nothing was going to happen so I pulled the filament out by hand, and inserted the new reel.

Then I pressed "load filament", and again nothing seemed to happen. I forced it in by hand and then cleaned off the purge extrusion.

"Resume" was a failure. The hot-end returned to the correct XY, but not Z. It recommenced printing but in mid-air, so produced spaghetti. I suspect it lost track of Z during the unload filament movement.

What I Think I Should Have Done

Pause print, then remove the old filament manually without pressing "unload". Insert new filament manually and purge manually, including wiping the nozzle. Then resume.

In my opinion, it should be possible to unload and load through the menus, and if it isn't those options should not be on the menu (the menus should be state-aware). Regardless, losing track of Z coordinate is surely a firmware bug.

I guess people doing multi-colour printing on the Tina2/2S (in layer bands) do this manually, or does the slicer have a filament change routine to bake into the Gcode?

[CrazyIvan]

The Entina on-line manual (which also mentions Weefun, I notice!) is sketchy on this matter:
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The manual does not explain how you "replace the filament".