TAZ4 Misfeeding - Hobbed bolt chewing filament

I’ve been experiencing a mis feed on the TAZ4 every month or so where the filament stops extruding after several layers have been placed. The first few layers always print fine, then it either stops or extrudes intermittently.

I had just gotten done printing with a clear ABS filament then switched to black ABS filament which I use plenty of.

This is the first attempt. You can see that some of the strands are missing:

The hobbed bolt had chewed threw the filament so it was no longer even extruding intermittently. Next, I cleaned the hobbed bolt and attempted again:

The extrusion definitely occurs with fits and starts. I stopped the print before it stopped extruding entirely. I think this last image is the most important, as you can see clearly how it fed the clear filament (left) vs the failed black filament (right):

It seems to get stuck every so often the catch, then get stuck again. We recently built an enclosure but I know the filament travel path is pretty low resistance. The ambient temp at the time of failure is 90F, with a bed plate temp of 95C, a first layer nozzle temperature of 230C which changes to 220C after the second layer begins.

tighten your idler arm bolts a bit.

Hi! This actually sounds exactly like the problem I just worked through. I ended up breaking it down in to two factors: too much tension on the idler bolts, and too much resistance to filament movement through the extruder.

It seems like everyone just tells you to make the idler bolts as tight as possible but what I found was that making them super tight just made it more likely that my hobbed bolt was going to eat the filament. So instead I left the idler bolts loose and then sent a long slow extrusion command to the printer so I could slowly tighten the bolts to just the point where everything seemed to be grabbing with no slipping.

Second, I had some issues with resistance in my extruder. I had recently had a PLA jam in the PTFE tube so I had to clean that up. If you need more details on that search my posts and read that thread. However I think the bigger factor was that for some of my PLA filaments 180 degrees was not hot enough to get a good flow. I was able to get good results with my blue filament, but not with my black or orange at 180 degrees. After turning the temp up to 185, I was able to get good results with my black. I have not tried the orange yet, but I suspect its the same problem.

Try bumping your temps up a few degrees to see if that does the trick. Every filament is slightly different!

220 nozzle temp seems too low. :question:

I always print all layers at 230 or 235.

Have you tried not dropping your nozzle temp? Or even raising it a little?

I tightened the arm bolts and got a few successful prints but then it just happened again last night. How much effort should be required to latch in the idler bolt? Should it just slip in or should I have to really press?

I happened to have another budaschnozzle so I’m giving the new one a chance. The problem is it’s intermittent and difficult to recreate. When I install the nozzle I put filament through it to put it “in place” before I tighten the screws to the rest of the extruder assembly.

We were having delamination issues for taller prints and someone had suggested lowering the extruder temperature so that way the print didn’t cool down too quickly. For awhile it seemed to have an effect but I wasn’t confident it was 100% the extruder temperature since we were tweaking other parameters. Lately I’ve been printing at 230C for all layers and I seem to have good results. Last night it was at 230C and still clogged.

Are you using one of the Lulzbot provided configurations?

Slic3r? Pronterface?

I’m wondering if your extrusion speeds are too fast.

What brand of ABS filament are you using? Is it straight from Lulzbot?

We are using lulzbot-provided slic3r configuration files and slicing in slic3r. Printing with pronterface. The ABS we’re using is IC3D from Amazon.

Make sure you’ve updated the filament diameter in your slicing engine. Use a digital caliper to get an average filament diameter, over a long (+5M) length of filament.

Turn your hot end up a bit, to 230C and see how that improves things. Which slicing profile are you using?

If I remember correctly, this one:

Medium ABS 0.35mm Nozzle, Medium, support off, 0.22 mm layers. My friend does the slicing, I do the printing so I don’t know exactly what he does.

We did update filmament diameter which I believe is 2.89mm. One thing that is an artifact of past issues (delamination) was increasing the extrusion mulitplier to 1.05. We figured at one time that it may help push layers together. Although I now think an enclosure with high ambient temp works best, the gcode is still generated with 1.05 extrusion multiplier.

How tight is the idler tension supposed to be, for example, when installing new filament - does there need to be a lot of force to pull the tab back?

It’s generally tight enough when the spring is compressed between 7mm and 5mm, with it finger tight (and a little bit more). When feeding the extruder you should not be able to stop the filament from entering the extruder when pinching the filament. Too tight and it can strip our the filament, too loose and it’ll do the same. Once you get it dialed in though it’s typically “set it and forget it”…

I run into the stripping issue occasionally still. I’m thinking of adapting one of these to a TAZ carriage. http://www.thingiverse.com/thing:27654/ Potentially a belted design to save on mass or something along those lines. Maybe with provision for a counter sensor if someone wants to figure out how to program it into the firmware.

I finally got it to stop happening. We were overextruding by 5% (extrusion multiplier) and the filament pressure was probably building up in the nozzle.