Aerostruder chewing up PLA... Anyone else?

I ran into the issue of the hobbed bolt chewing through PLA semi-frequently with the stock toolhead (Taz 6 and sometimes my Mini as well). When the Aerostruder was announced I was excited, thinking that a totally different hotend and toolhead design would have a good chance of eliminating this issue for good. I did several long prints just fine and thought “Great! Must be fixed.” Nope. Last night it chewed through the filament a few hours into a print. Re-tried the print twice this morning and both times it chewed through it within a couple minutes of starting the print.

Anyone else experiencing this? I tried increasing my z-offset to make sure there wasn’t too much pressure, messing with retraction speed and distance, and printing a little faster (to hopefully lessen the chances of heat creep), but none of those seemed to help.

I’m pretty bummed, because once I had a few prints on the new toolhead I went ahead and ordered one for my mini as well.

Try tightening your tensioner. It sucks getting to it but mine was chewing up wood PLA until I tightened it.

Directly behind the silver thumbscrew on the Aerostruder is a tiny window. A nut should be visible in this window, ideally in the middle of that window range. Adjust as needed, some materials may like more or less tension.

You may also need to adjust the extrusion temperature hotter or cooler by 5 degrees or so, as the different colorants used by different vendors will influence the ideal extrusion temperature. Reach out to our support team for help, include the slicing profile use, the filament vendor, and color: LulzBot.com/Support.

I’m having this same problem, but with Lulzbot brand ABS on the Mini Aerostruder. Tested using the same print about 15 times yesterday. Each time, it would print perhaps 10-20 layers, then grind out the filament.

I know all the typical causes of grinding, and tried all the typical solutions… I tried different idler tension from very loose to very tight, everywhere in between at 1/2 turn increments. I tried increasing temp. Cleaned the hob after every grind-out. Checked that temp is stable during extrusion, that heatsink fan is running and heatsink is cool. Priming flows freely, no pigtailing, no clog (even tried a second Aerostruder to eliminate possible nozzle/heater/thermistor issues). Filament is dry. E-steps are calibrated. Spool is turning freely.

I played around with retraction settings. Started with default CuraLE retraction, 1mm @ 10mm/s. I tried less retraction (0.5mm), more retraction (2mm), slower (5mm/s) and faster (15mm/s). None of that helped. Turning off retraction entirely solved the problem, but made for a messy print. The print doesn’t have excessive retractions – perhaps 5-6 per layer – and never in rapid succession.

The same part, printed with the same retraction settings, succeeds at 0.25 layer height. At 0.38 layer height it grinds out after a few layers. Also note that this part has 80% infill, so when printing infill a lot of filament is being extruded quickly – so back-pressure may be involved. Temp graphs shows stable temp during that, but I tried increasing temp anyway from 240c to 245c, then 250c, along with different idler tensions, but still had problems. I tried reducing infill speed to 40mm/s, but the problem still occurred.

Swapped in a second Aerostruder and experienced the same problem. After fighting it all day, I finally switched back to the Hexagon and had success first time.

Over the previous few days, I had run a bunch of PETG, PCTPE, and Ninjaflex prints through the Aerostruder – and never had a single grind-out problem. But all of those prints were also smaller layer heights, few retractions, and a bit slower (a lot slower with the Ninjaflex).

My current conclusion: The Aerostruder has a high tendency to grind out filament, at least when high flow / nozzle pressure is coupled with even a low frequency of retractions. I don’t see any logical reason for it, but that’s my experience so far. If there’s an adjustment or setting that fixes it, I certainly haven’t found it yet.

EDIT: Just ran a 2hr print, same filament, same 0.38 layer height, same idler tension, and this one had a LOT of retractions – but almost no infill. It completed fine, no grinding despite hundreds of retractions. So again, the problem seems to be retractions in combination with high volume extrusion, as seen with doing a lot of thick layer infill.

I’d like to know if others are having issues, too.

Playing with the idler tension (boy that thing is a pain to adjust now) seems to have fixed it in my case. The window of the amount of tension that will work seems to be much smaller on this than on the original toolhead.

@wermy - What tension setting(s) worked for you, for which filament(s)? I’ve searched around for recommendations, but everything is really vague. Maybe we could share, at least as a “starting point”, what setting(s) work for what situations.

I was using 2 turns from “full loose”, and had lots of success with PETG, PCTPE, and ABS. Ninjaflex fed fine at 2 turns, but was underextruding – lessening tension to 1.5 turns helped (still needed to increase flow to 115-120%).

For sure, with that small stiff spring, even a small adjustment (like 1/4 turn) can make a big difference in the amount of pressure applied – so that could be the answer. With the print that kept failing for me, I tried everything from 1 turn (least pressure) to 4 turns, at 1/2 turn increments. Maybe I should have tried 1/4 turn increments?

I’ve only had problems with specific prints (as mentioned in earlier post). The prints I had problems with were those that had both some retractions AND a high extrusion rate (i.e., thick layers and lots of 80% infill). Everything else has printed just fine.

I’ll have to check when I get home but it was definitely on the looser side. A modified carriage that allows you to tighten it easier would sure be nice.

As a side note, that thing can get TIGHT. I mistakenly tightened it in stead of loosening it, and the filament came out pill-shaped because it was squeezing it so hard. :open_mouth:

One other thing I would check Wermy is the idler after a clog. If my Aerostruder clogs I find that the hobbed bolt has a lot of filament residue in it, so make sure to clean that out before the next print with compressed air or a dental pick. If you want to post the gcode you are trying to print we can take a look at it and see if there is anything problematic either with the print or settings.

I experıence the same problem with ABS. Did not try any other fimalement yet.
Does anyone have an idea for the optimum spring tensioner?

one thing to do is adjust the tension after 10 to 20 layers have printed.

it seems that heat creeps up the filament some during the print and softens it where the tensioner is pushing, so the tension setting you set when the filament was cold may not be enough when it warms up.

Ideally the spring is supposed to handle this variation in hardness as the filament warms up, but I think the spring rate is too high on these things, and there is not much room in there for a different spring.

We’ve been having this problem on our TAZ6 with the Aerostruder upgrade. One particular spool of filament in our supply regularly exhibits this phenomenon: SHAXON 3mm PLA (yellow), purchased from Fry’s. Other PLAs we have from Polymaker and Verbatim work great. The SHAXON spool in question used to work reliably on the old V2 Hexagon print head, but I’m thinking it may have been a more forgiving setup.

After running out of ideas, I finally took the digital calipers to the filament itself. Its diameter gradually varies from 2.97 to 3.06 about every 20-30 cm. Our other filaments are right around the 2.85 size.

Searching about for a spec on minimum a maximum filament diameter for the Aero, I came across an old Wiki article on E3D’s site, stating a number of interesting things:

In general the E3D-v6 hotend is highly tolerant of most printing conditions and is designed to accept the vast majority of filaments on the market. There are however some things to be aware of:

Filament must be within acceptable diameter tolerance. For 1.75mm this means 1.70mm - 1.80mm and for 3.00mm/2.85mm the filament must be between 2.80mm and 3.05mm

Excessively long retractions will cause issues by dragging soft filament into cold areas. E3D-v6 hotends need less retraction than most hotends. For direct extrusion systems you should use anywhere from 0.5mm-1.0mm, for bowden systems you might want to go up to 2mm. Retraction beyond 2mm is likely to cause issues.

The heatsink must be cooled! Heated chambers, fan ducts that restrict flow, and not having the fan running at 100% at all times are common causes of issues. The heatsink should be cool to the touch at all times. If your heatsink is warm to the touch then you have a cooling issue that must be addressed.

It looks like the latest grind-out happened at a section where the filament measured 3.06… hmm!

Retraction is Cura LE default (1mm).

The heatsink is warm to the touch, but then again it is 35C in the shop where the printer is. Almost seems like the Aero head needs a bigger fan, or better yet, liquid cooling (which I understand E3D is developing already).