Prints fail around the same Z pos

[gregthoman]

This seems to happen mostly when using Black PLA.
I'm using stock settings for a Makerbot Rep 2

As I understand it, the Makerbots rep 2 sense temperature different than other printers, so the 230 temp is correct for PLA.

It doesn't matter if I print 1 or 4 of these parts or parts like them... When the layer get's small, the extrusion stops and then starts back up again later. It's the the nozzle is getting clogged up and then releases later on in the build.

I went through the printing guide https://www.simplify3d.com/support/prin ... e-of-print and tried the suggestions under stops extruding. But they didn't address this correctly.

I've tried many things including:
No Fan (less Fan)
Over Extruding
Higher and lower temps

I am at a complete loss here... Please help.

[CompoundCarl]

Well I would print it again and watch the extruder closely when it gets into that part of the print

Things to look out for
- is the extruder motor still turning
- is the filament still moving into the extruder at the same rate as it was before

If you notice that the extruder motor stops spinning or the motor is spinning but the filament isn't advancing, then that would help narrow in on what's causing it

[dkightley]

I wonder if the filament is sticking in the nozzle barrel, which is something I've had a few times on my Bot, particularly where there's a lot of retraction going on.

For several months now, I've been using PTFE lined barrels which tend not to be so prone to jamming and allow for quite large retraction movements. These barrels can be picked up easily and cheaply on Ebay...but make sure they actually have the liners included! They're quite easy to change, but need a complete strip of the extruder. If you do use them and change filament, feed a bit of filament through the extruder first before extracting to avoid damaging the liner with un-softened filament.