Dual Extruder Gears Slipping HELP!

Hi All

So I recently got my Dual Extruder for my TAZ 5 and to be honest it has been a headache. The test print with the provided ABS was fine. But ever since I moved to PLA that’s when the trouble started. I’ve never had any issues with PLA and find it to be very forgiving. Well this is not the case with the new dual extruder as I have not had even one successful print. Both gears on the extruders start skipping and springing back. this happen usually 5-10 mintues into a print. Sometimes its one gear others times it’s the other. It has become very frustrating. Many times the gear would start skipping and after pausing the print I would test the extruder and it would be fine or stop skipping after 20mm of extrusion and i could run 200+mm with no problem. Upon resuming the print it would start skipping a few minutes into continuing it. Most times depending on the idler screw tension there would be no filament stripping and would only occur if I forced it to extrude by hand. These are all the things I’ve tried to troubleshoot the issue. let me know what you think.


  • Tried all temps ranging form 190*-225*
    Print Bed temp 50*-70*
    Changed fan speed minimum (40,50,60,70)
    Let machine Cool completely and then retried


  • Tried multiple leveling ranges from the print bed
    Tried changing flow % to 70 and 80 and 90
    Tightened set screw on small gear on motor
    Tried all levels of tightness with the idler screws
    Checked Estps (E0 825 E1 833) and reajusted as per calibration instructiosn


  • Cleaned extruder bolt teeth
    Used eSUN cleaning filament
    performed many cold extrusions

I have yet to work with retraction which may be the culprit. The reason I believe this to be true is when I print with only one printhead it is successful. I did a test print with the back extruder and a second one with the front and both were successful. It is only when I do a dual extrusion print that I have problems.

The blower fans probably aren’t enough to cool the heatsinks… combating heat creep.

A community member posted a modification which utilizes two 25mm heatsinks. I think that’s probably the best solution for PLA.

I agree with kcchen_001. The fans on the heatsinks for the dual extruder (and the stock head, for that matter) will not keep PLA cool enough to print successfully.

This will fix the problem:


You are right, it has to be a heat creep issue. When I start from a cool toolhead and set my hotend to 183* it fails about 15 minutes into the print, but when i set it to the recommend 205* it fails 5 minutes into the print. Why doesn’t Lulzbot address this issue by upgrading their toolhead with adequate fans? I bought this for PLA & PVA and the fact that is doesn’t work without mods is kinda silly. Thanks for the link, I just ordered the fans. I wish there were still stores that sold these so I didn’t have to wait for them to get here. Im also wondering if I print them with the polycarbonate that would make the ducts more resistant to higher temps for ABS. What do you guys thing?

It is very frustrating to have spent so much for a printer, then an additional $500 for the dual head, only to have it not work on the material I need to print. I probably spent three times the cost of the printer in my employer’s money researching this problem and trying to make it work, before finally being successful.

Lulzbot may have addressed this in the Taz6.

I do somewhat share your concern about the ABS shrouds surviving the environment for printing ABS and higher-temperature material. My gut feeling is that as long as the fans are functioning the shrouds will survive, but I have not tested that. You’ll notice that I covered the bottom of the shrouds in copper foil tape, just because that’s what I had on-hand. I don’t really know if that helps, but it was easy enough to do. A better approach might be a thin metal shield that is separated slightly from the shroud, so that it doesn’t conduct heat directly into it.

I will say that after probably a total of fifty hours printing PLA at 205C with a 60C bed, the shrouds show no signs of discoloration or distortion. Sorry, that’s the only data point I have. I want to do an extended “torture test” by just having the printer sitting there at 240C/110C with the head right down at the bed, but I don’t want to do that until I have a couple more shrouds printed and I am ready to go in and rebuild the head again. Right now that is a low priority for me, since it is working so well with PLA and PVA, and that’s about all I want or need to print with.

Just Printed these in Polycarbonate. First time using the filament and I have to say this stuff is pretty strong. I’m actually surprised how much of a rock these are for there size. I’ll let you know how it goes when I get my fans.

Wow, you don’t mess around!

For your convenience, here’s the McMaster-Carr numbers on a couple of the parts:

91287A051, M4 x 35 stainless steel cap screws, pack of 50.

94868A036, M4 x 6mm threaded standoff. I thought I was going to use threaded standoffs under the clips, but then realized that through hole would be easier to assemble, so I drilled out two of these to make them through-hole spacers. I still used threaded ones on top of the clips, but any M4 nut should work.

If you print the other clip I just uploaded yesterday, you should not need the lower spacers, but it will constrain you to using the clips on only one side of the fans.

Thanks for the references!

I’ll let you know how it works. I should have all my supplies by end of day tomorrow. I’ll run a ABS torture test with the polycarbonate dusts to let you know how they stand up. thanks for all your help so far.

Awesome, but I hope you do a few PLA prints before you do the ABS torture test!


Thank you so much! This worked beautifully. I made a few modifications to the shroud and clip so I put them on the same side and use Hex screws (OCD I have to keep it all Hex for my brain to be happy). I also wanted the air to go to one side so the hot air didn’t recycle. I used an M4x 35mm from bottom .

Here are the modified parts to fit 2-56 hex screws and the clips for back and front extruders
Clips.stl (1020 KB)
Shroud.stl (1.79 MB)

Wow, that looks great! And the Allen head screws are a nice touch indeed.

Have you printed PLA with it yet?

Also, I would like to know… Did you just use my latest revision of the clip, and mirror it? It looks like there is no spacer on the underside, so I am assuming that is what you did. However, I haven’t tested that part yet myself (I am using the first revision), and I would like to know if any further changes to the design were necessary, aside from mirroring it.

Thank you for posting the pics and the update. So glad this worked out for you.

I have printed in PLA. I did the Lulzbot keychain and it completed for the first time ever! I’m currently doing a gearbox with PVA supports. I used your newest clips as a starting point. I actually sat down with a millimeter ruler and using the program Shaper3D for the iPad Pro recreated both the clip and the shroud so I could use the screws I have and so that it printed better in Polycarbonate. It was a mirror flip for the clip.

Cool! The PLA/PVA process is SO worth the effort. By the way, I did some adhesion tests and found that regular Elmer’s Glue-All in liquid form works better than anything else, including three different kinds of glue sticks, for PVA adhesion to the bed. It is definitely worth the hassle of spreading the liquid.

Regarding the parts, I could have, and still can provide step files to be imported into a CAD system for modifications. Sounds like you have a method that works, but let me know if you want the parts in step format.

Really glad it’s working.

I guess i spoke too soon.

I’m back to square one. PLA stops extruding mid print again. I’ve cleaned my nozzle, tried every setting under the sun and nothing. If i’m lucky 10% of my dual prints succeed and only if they are small. At this point it looks like my dual extruder is going in the box. Hopefully Lulzbot will have a v3 that resolves these issues. Then maybe I can upgrade it. Being that I’m really looking to print ABS or HIPS it’s back to a single extruder. I just feel duped out of $500.

Sorry to hear that! Is it possible that your fan has either stopped working or has reduced performance?

I have had only one hiccup in perhaps 50 or more hours of printing PLA since doing the upgrade. I did start running my extruder body fan after that hiccup, I don’t know if it really helps, but it can’t hurt. Still, my sense is that just the heatsink fans are doing the trick. There must be something else going on in your case.

How is your clearance above the bed? Too close, and the back pressure can jam it up. That’s more likely with more flexible filaments like PVA, but it’s something to look at.

Also, is it possible that when you installed the shrouds that you may have weakened one of the thermistor wires, and it has since broken? That happened to me. Are your temperature readouts normal on the display?

At this point I don’t think it’s the fan but some other hardware issue. This all started after my PC motherboard died. I had the printer plugged into the same outlet. My guess is that there was a power spike that may have not only effected my PC, but the printer as well. I never had issues printing PLA prior to that with pints over 12+ hours succeeding. I also switched to the duaI extruder right after that event. Now that I switched back to the single extruder and the issue persist. I also had a strange error where after a failed print the Z axis just kept climbing. Had I not been there the printer would have been down for the count. I don’t even want to think about what that would have looked like afterwards.

Would you be willing to post up some numbers for printing with PC? I’ve been trying some PC prints over the last week with mixed results. I’ve found UHU stick works really well for bed adhesion, but getting warping of the base. The warping doesn’t show up during the print because it sticks really well to the bed, but when I lift the printed piece, there are clearly some internal stresses because the bottom warps up and I get splitting at about 3-4 mm above the base of the print.

I’ve been working with different nozzle and bed temperatures, the latest being 260 at the nozzle and 120 for the bed. Printing a 0.4 mm first layer and 0.2 mm subsequent layers.

The previous dual extruder was never a fully working product, and all of the flaws from that have merged into this version with the addition of even worse heat creep from the underspeced fans.

Total waste of $500.

I’m glad you posted this. I was about to get the dual v2 for my Taz 5 but now that I hear about it, I’m going to pass on it. My original Taz 5 I had the creep issue too, the stupid blower fan blew up a week after we got it. I ended up getting a 40mm blower fan and no more heat creep. I saw the shroud with the 20mm fans, but it looked like it really didn’t fix it either.

I just ran 3 40-50hr prints the past two weeks. Massive pump housing for work. It’s been great but cleanup has been a pain due to the cavities in certain holes. So I was tempted to get it so I can use the PVA soluble filament.

It’s just so ridiculous that Lulzbot continues to manufacture crap that don’t work, especially when it’s not a $500 printer.

Has anyone have good success with PLA/PVA combo with long running jobs on the new v2 extruder?

I got some good dual prints recently. I had to place not one, but two small desk fans near the printer for it to work. Haven’t had a problem since. It just blows my mind that after everything I tried it was desk fans that made it work. It was actually suggested to me by their support team, but it seemed so ridiculous that I didn’t even try it till recently. see Email below

On a side note… Lulzbot, if you need to do something like this to get a $500 toolhead to work properly maybe its time to go back to the drawing board. I’m someone that likes to have a clean work area and streamline look for where I place my printer. Two desk fans shoved as close as then can be next to the printer just looks terrible.