Dual extrusion oozing/colors bleeding

Hi,
I recently added a second extruder to my home made printer and converted it to Bowden tubes.
It now has two E3d V6s.

Unfortunately I get filament oozing and the colors bleeding in dual extrusion prints:


Things I already tried:
-Printing with ooze shield and prime pillar
-lowering the temperature (PLA) to 190 degree C
-longer retractions. I get jams with everything over 6mm
-faster retractions up to 100mm/s
-printed those little anti release clips for the Bowden couplings

Do you have any idea what else I could change?

Daishi

Did you try to use smaller nozzles? The smaller they are the less they ooze.

Depending on the firmware you can change the standby temperature for the unused tool. Print a wider prime pillar to allow the unused tool to cool down enough.
Between every toolchange you have to wait until it's heated up again.

Thanks for your help!

Unfortunately I only have 0.4mm nozzles, so I had no chance to try different ones.
Lowering the temperature of the unused tool sounds like a good idea. It should be possible with a tool change script in simplify3d.
The only downside is that it will probably double the printing time when the printer waits for the second nozzle to cool down.

Part of the cooling time can be used to prime the nozzle in duty. The heating time for that nozzle is shorter than the cooling time, but that process can run parallel too.
I've seen a CoreXY printer which is able to automatically change tools in no time. That is a clever idea, because the gantry weight is lower and the unused nozzle can ooze while it cools down without ruining the print.

Edited 2 time(s). Last edit at 09/16/2017 03:38AM by o_lampe.

Thanks for your help!

I tried a script that changes the temperature of the unused nozzle to 160°C.
Here is the result, still on the brim:


Nearly perfect !
The print time went from 5 hours to around 7, but thats worth the difference.

Your link with the changeable hotends is really cool! I should try something like this some time.

Awesome!!!
This makes me want to own one.