Extrusion Problem with Dual Extruder v2

Hello everyone, I’m having some problem with my Taz 5 with a Dual Extruder v2.

I’ve had successful prints before, however recently it seems I just can’t get it to print correctly. The back extruder would always extrude maybe just the first and second layers and then the back extruder would seemingly get clogged. The next layer above would either be very thin or sometimes globby. I have no problem with the first extruder which extrudes PVA.

I’ve tried Matterhackers white PLA regular and pro editions, Gizmo dorks and ProtoParadigm white PLA and they all give me the same result. The extruder idlers are all at 5 mm between washers, I measured it out with a digital caliper.
I’ve tried many cold pulls and I can see the light coming from the nozzle when the extruder is empty.
I’ve tried setting the filament diameter to 3 mm from 2.85 mm.
Both extruder heads are leveled and seem to give the same amount of friction.
Tried moving the filament holder above the Taz 5 to see if that fixed anything.
It seems that the microblower and fans are working.
Tried setting fan to run with min 90% above .25 mm.
Tried temperatures from 190-220.
Tried with microSD and direct connection.

I’m wondering what else I could try? Thanks in advance.

My Setup:
Cura 18.03
Windows 10

If you are consistently getting strip outs in the first layer or two, it will most commonly be due to having the initial Z height too close to the plate.

If there is not enough room for the first layer to extrude, it will create an extra back pressure. This backpressure can cause the hobbed bolt to grind into the filament, causing filament to get caught in the teeth. Once filament becomes caught in the teeth, extrusion will be spotty/impossible.

As this is only happening on the rear extruder, you will also want to check that both your heads are level. Xrobots just put up a great video detailing install of our Flexy Dual (same process.) https://www.youtube.com/watch?v=IZjsNsEiRyw

We hope this helps!

Thank you for the fast reply, I’ll do some more tests.

The little micro squirrel cage blowers used on the Dual Head V2 are not nearly enough cooling power for reliable printing with PLA. The filament conducts heat, and it will swell up and jam near the bottom of the extruder body, where it enters the hotend. I had to design some shrouds to use with larger fans. This appears to have fixed my PLA extrusion problems 100%:

https://forum.lulzbot.com/t/adjustable-heat-bed-glass-mount/38/1