5 min flexi fix for sapphire pro 2 extruder

The extruder that comes with the sapphire pro2. Is a bondtech double geared job.
Great for things like pla, pet, abs etc.
But out of the box is completely useless for flexible filaments.
Aat the slightest back pressure, the filament snakes back on itself and wraps up behind the top of the extruder drive gear.
Attachment 16313

The grooves in the drive gear are just too shallow and the gaps between the filament comimg in and going out before and after the gears are about 1mm too big.
It's just a poor design for flexibles all round.

So I spent most of an afternoon farting about with printed inserts to block the space off:
Attachment 16314

But the gap was just too small to get something small enough to print well. Plus the bloody things would not stick.

So then I thought I'd do it properly.
And got the 5 minute epoxy putty out :-)
Attachment 16315

It's a neat little container with small pellets. I only used half a pellet.

Once you've squidged it around till it's the consistency of old chewing gum and quite warm and sticky, you've got 5 minutes before it's too hard to work.

Attachment 16316

Job done !

So did it work ?

Yes and no.
Yes i can now print the newer and stiffer flexible tpus - in fact they'll happily print at 40mm/s.

But also no, as the older 'wet spaghetti' filaments lile filaflex and the original ninjaflex - I have a roll of each - still manage to escape, only now in the opposite dierection lol.
Attachment 16317

The problem is that the second gear is hinged and when screwed down is surrounded by a lot of empty space.
So, at some point in the future I will get the putty out again and fill the space, using the gear to make it's own shape in the putty and then tamp it down just enough for it to still rotate smoothly.
Another 5 minute fix - 'cos that's all the time you have lol

But for now it's happily printing the tpu I'm currently using and the old stuff isn't going anywhere.

So I would say this is mostly a success :-)

The printer now has: cable ties, self annealing plumbing tape and epoxy putty - all i need now is somewhere I can use duct tape on it for the full 'handyman-set' :-)

But if you've got one of these bondtech extruders and want to use most currently sold tpu - this fix will do the job.