Dual Extruder V3 - why angle the filament channel?

I’ve done several multi-hour prints that failed hours into the print because the filament gets stuck in the chamber and quits feeding. This never happened with the single extruder because the channel was straight so the filament didn’t have to go through any gymnastics to make it to the nozzle. For some reason this head was designed in a way that requires the filament to have to significantly bend to feed. I’ve used the jig to tighten the screws to the right distance but it didn’t matter. I tried a few turns tighter but it doesn’t matter. Tightening these screws and the curved chamber also makes it way too hard to load filament. Most of the time I have to untighten the screws to be able to hold it open to load, which then has me counting turns to get it back to jig depth. This seems like a bad design to me.

I’ve wasted days and 2 spools of filament on this V3 head between the temperature issues recall and these feed problems. I wouldn’t be so mad if it would screw up instantly so I didn’t stand around waiting hours for a 15-hour print and have it suddenly get stuck 2 hours into the print.

Is anyone else having these kinds of issues?

The shared heat break parts and hot ends close together are key features of the V3 design. The drive end is spaced widely apart by the big drive gear and stepper motors. So you get the curved path to bring the feeds close together.

I had a problem with the V3 grinding the filament after a while (several hours into a print). I ended up running the extruder(s) a little hotter (+5 ~ +10 degrees) and the grinding problem went away.

With the V3 it is really important to let it get completely warmed up before removing the filament, including extruding some before reversing and pulling out the rest. If it isn’t hot enough the filament will stick in the heat sink, resulting in gnashing of teeth. Also, nozzle removal, disassembly and careful drilling to get the stuck filament out.

If the filament channel were vertical, the idler/tensioner levers would be practically inoperable… not to mention no access to the tension thmbscrews.

The Dual v3 gets even better when the filament breaks past the hobbed gear. Time for some filament runout sensors…

Im actually amazed at this point they havent incorporated one into a tool head. My cheap chinese CR10 ships with one… For my 2 S5 (500mm^3) machines its an absolute necessity. Just finished a part that used more than a 3kg spool…

I considered this guy as an active monitor


Since itll detect jams and such as the OP was seeing.

I would suggest you look at your temp settings. There’s a few massive flaws in the cura programming - the cold start can cause jamming issues if you don’t let it warm up before starting extrusion. If you run your temps higher and wait longer to start, you’ll see some improvement. Also, loop your filament differently than currently set up if you have an issue. The more you have the filament trying to reverse curl, the more you’ll fight it. If the curl is going with you, it will be a bit less. And more heat makes it much easier.

Then you should look into ooze shields and your retraction settings since they will change once you up the heat.

That’s certainly an interesting upgrade I’ll have to look at to check for filament feed; though I’ve just about never had a problem with running out of filament, it’s always something going wrong in the hot end or at the roll so it just doesn’t MOVE.

I’ve noticed this problem with the feed angle and hobbed gear chewing the material and stopping the feed. I have had to tear down my dual extruder v3 a couple of times to recover.

Once a small chunk (3mm x 3mm) of material got stuck in between the feeder and heating block when pulling material for swap. Too high to melt it, and wouldn’t drop into the nozzle because of the change in angle where the two components meet.

Another the hobbed gear chewed the material feed early into an overnight print, and enough material oozed out to create a void in the nozzle, with the block unable to melt the material at the top of the block. Had to disassemble and torch to clean out that one.

I would recommend an increased diameter hobbed gear, with more surface area to grab the feed material. Increases resistance to both chewing filament and the force required to feed.

The single extruder feed mechanism is certainly more robust.

Sounds like your idler levers aren’t applying enough pressure on the filament for the hobbed bolt to get a good bite. When you unload the filament, can you feel the teeth of the hobbed bolt against the filament?

Make sure to use the idler spacer to get the right tension on the lever springs. I like using the spacer on the unloaded lever… And honestly, it doesn’t hurt to give it another turn or so. The limiting factor would be the ability to unclamping to remove the filament. I guess, as long as you get 3-5mm of movement on the lever it should be clamping the filament to the hobbed gear pretty well.

I’ve found that I have to print filament a little hotter with the V3…

Oh well… My Dual V3 is doing great. Prints from either extruder look like a single nozzle toolhead. There is a learning curve coming from the v2. I think there’s a lack of appreciation for this toolhead from those who didn’t experience the cludginess of the v2.

In my case for the idler to hobbed gear tension, yes, I can see/feel where it bites the material when retracted. It’s a couple of turns tighter than spec (spacer with no filament loaded). Could try clamping down all the way. Was thinking of replacing the idler bearing with a rubber bushing to see if it provides more even pressure against the gear.

Last attempt to up temperature for less resistance going into the nozzle wasn’t helpful. I felt it made it easier for a nozzle void to be created once the feed stopped.

I’m currently planning to change either the approach angle of filament again, or attempting to lubricate the reel in order to have less friction through the channel. I switched to an overhead filament holder when I received the v3 because of binding at the entry point to the tool head. But might try a tabletop holder on the left and right of the bed so the spool curvature matches the entry curvature better…

I just wish there was an easier way to load the filament. It’s pretty much a blind procedure and if I’m unlucky it takes forever until the filament finds its way into the channel just right.

Okay… understand what you mean by nozzle void from “ooze”. If the increase in temp worked, then try adjusting the retraction distance. The retraction will create a vacuum that reduces / slows the ooze or dripping of melted filament…

@Spacemonkey1033 - You’re probably doing it, but make sure to cut the filament into a “chisel” before inserting. Then insert chisel tip down… This is a case where a picture is worth 1000 words: https://ohai.lulzbot.com/project/LulzBot-TAZ-5-Dual-Extruder-v3-Install/accessories/

I just remove the spring screw all together so I can get a good visual of the filament and hole it needs to go into. Its not worth fighting trying to hold the spring and insert the filament. I’ll do an angle cut on my filament, that helps a bit too. Sometimes I’ll even need to put a little bend in the filament that bends the tip downward in the direction of the hole.

And if you’re using PLA you’ll surely experience heat creep up the filament to the feeding gear. They put a very under powered fan on the v3 Dual Head, only 3.87CFM

I’ll be replacing the heat sink fan with this one https://www.ebay.com/itm/272607041555 ; claims to push 11CFM. Probably a little overkill but… better than failed prints.

The fan on the single head that came with the TAZ 6 is slightly deeper than the one on the v3 Dual Head; don’t know what the specs are on it but I’m guessing its the next class up of 6.xx CFM. I do not experience the heat creeps with the single head and PLA filament.

How you you replace the heat sink fan? I’m pretty sure I’m having the heat creep issue as well?

All the fans on my TAZ 6 Single Extruders are the same part (same part number) as the one on the Dual Extruder V3 and the Aerostruder, the 5v version of https://www.lulzbot.com/store/parts/40m … w-flow-fan.

Replacing the fan requires removing the 4 hex head bolts, cutting the wires on the old fan. Splicing the wires to the new fan, replacing the 4 hex head bolts. On the Dual Extruder V3, the bolts are very long so replacing the 40x40x10mm fan with a 40x40x20 fan will require finding 10mm longer screws.

Amazon sells this Noctua fan (Amazon NF-A4X10-FLX-5V) which is the same size at the stock fan but has a 25% higher flow, 4.82 cfm (stock fan 3.87 cfm).

Has anybody had any luck with replacing the heat sink fans? I used the Noctua NF-A4x20 5V with 9.4 cm3 flow, but I’m still getting heat creep with PLA. I’m thinking about replacing the other fans with Noctuas as well.

I have experienced the heat creep problem very much with the DualExtrusion v3 printhead. I am surprised to read you’re still experiencing the problem with a 9.4 cfm fan. I as much as bought the fan I mentioned above, bought the longer screws to mount it and then stopped short of replacing it because I may have found my root cause.

What I have great success with is turning the filament tightening screw just enough to where it begins to push on the filament. As the filament goes into the print head’s hole it will touch the top of the hole, when tightening the screw down you will see the filament move away from the top edge of the hole because the screw is beginning to push on it. That seems to be just the right amount of tension and I haven’t had any problems since.

It seems around the 2 hour mark is where I usually would experience the heat creep problem (printing from a cold machine, sooner if I were doing back to back prints).
Try my technique and see if you still experience the heat creep.

Thanks, I’ll give that a try!