Dual Extrusion and Clogs: your experience?

[Dim3nsioneer 557]

After having upgraded my Ultimaker with the Dual Extrusion Kit, I ran into my very first clog today after having run the Ultimaker for quite some time in a single extruder setup without any clogs.

As gr5 pointed out in a previous post (http://umforum.ultimaker.com/index.php?/topic/3022-ultimaker-suddenly-stopped-working/?hl=clog&do=findComment&comment=22238), it can happen if the PLA stays inside the heated hotend for too long.

With the dual extrusion this situation becomes more likely. For larger prints at small velocities, an idle time of up to 10 minutes becomes possible.

Has anyone made a similar experience? What strategy for the retract length might be good?

The second topic to be addressed is the underextrusion happening after a long idle time as the remaining filament in the hotend is slowly oozing out of the nozzle and missing at reactivation of the extruder.

 

[3dcase 37]

Mine is running with a switch retraction of 12 mm, for me the 16 mm standard cura gave the same clogging..

Until now I'm using two separate walls or parts, one for each extruder, to keep it primed, and it helps cleaning the nozzle's.

Or/and use a plugin to heatup the 2nd nozzle at a certain height, but even than you need a separate part for the 2nd to start printing and priming a couple of layers before your main part.

But i'm in for other ideas!!

 

[codemaven 0]

I havn't done much dual extrusion printing since I got it, but with the printing I have done I've changed the m109 for the second extruder to an M104 and placed it a few layers before it is required so it doesn't heat up until just before it's needed... Just have to put it far enough ahead to give it time to reach temperature when it's required.

I believe Daid intends to add a 'wipe/prime tower' feature to Cura which will also help this... But I have no idea when this would be available. A primetower basically just ensures that both extruders print at least a little bit of filament on each later. You can manually add a prime tower to your model by just creating a couple of objects off to the side (for each color) that are the same height as the model so they get printed along with it.

Regards,

Troy.

 

[Dim3nsioneer 557]

... for me the 16 mm standard cura gave the same clogging..

...

 

Thank you for confirming! I thought the 16mm might be a bit too much...

I'll try the tower/wall thing. However, if one uses a tower for each color, switching off the heater for the second extruder isn't an option anymore...

B.t.w.: Does anyone know if there will be a new stable Cura version comming soon? Maybe on the 21st? Maybe with the extended support material structure some people already tested?

 

[3dcase 37]

Thank you for confirming! I thought the 16mm might be a bit too much...

I'll try the tower/wall thing. However, if one uses a tower for each color, switching off the heater for the second extruder isn't an option anymore...

B.t.w.: Does anyone know if there will be a new stable Cura version comming soon? Maybe on the 21st? Maybe with the extended support material structure some people already tested?

 

In my case the hotend clogging gives more problems is the older hotend, the new one that came with the dual set is better (but almost new). I think, in the old one the brass tube and for sure the white Teflon thing are worn out, and do not guide the filament anymore.

For the towers, you can switch colour in the tower(s) as well. In this Youmagine thing I used TweakAtZ plugin en and angled cut in the tower to prime the 2nd hotend.

https://www.youmagine.com/designs/tin-tin-rocket-dual

 

[Dim3nsioneer 557]

I had my clog in the brand new hotend between the Teflon part and the brass tube. As far as I can see, the hotends are not well clamped by the wood parts in the Dual setup (compared to the Single setup where the bottom plate is fixed to the rest of the wooden part of the print head). There should be a better way to control the spacing between the middle and the botton plate of the print head as the bottom plate clamps the Teflon part... I'm currently thinking of adding four springs between middle and bottom plate to push the bottom plate down...