Heat Creep on Taz 6 Single Extruder 2.1 - anyone else?

Help with printing with specific plastic filaments.
nopick
Posts: 1029
Joined: Mon Sep 09, 2013 11:14 am

Re: Heat Creep on Taz 6 Single Extruder 2.1 - anyone else?

Post by nopick » Mon Mar 20, 2017 12:24 pm

Yep. Insert the tube, tighten up the idler and adjust the slicer filament diameter and retraction settings. I had to retract a little more to prevent stringing.

I will post some pictures tonight.

wermy
Posts: 20
Joined: Thu Jun 09, 2016 7:34 am

Re: Heat Creep on Taz 6 Single Extruder 2.1 - anyone else?

Post by wermy » Mon Mar 20, 2017 12:44 pm

nopick wrote:Yep. Insert the tube, tighten up the idler and adjust the slicer filament diameter and retraction settings. I had to retract a little more to prevent stringing.

I will post some pictures tonight.
Thanks! I've got a few rolls of 1.75mm PLA just sitting there, can't wait to give this a try and see if it fixes my jams! :D

paulmorley
Posts: 48
Joined: Tue May 05, 2015 8:28 pm

Re: Heat Creep on Taz 6 Single Extruder 2.1 - anyone else?

Post by paulmorley » Mon Mar 20, 2017 3:00 pm

Hi all. Thought I would share a couple of thoughts I have on the subject of heat creep and jams. For the purpose of the diagram i've created, i'm intending only to communicate generalized associations between 'Print speed', Hotend Temperature and filament jams'. I'm also not trying to address any of the clogging situations having anything to do with foreign debris in the nozzle tip. IE, I'm only describing jams typically associated with heat creep, where the filament becomes difficult to pull out of the head even at temperature.

In the diagram below, I've tried to describe the correlation between hotend temperature, print speed and risk of filament jamming. And to be clear, when I say speed, i'm simply describing how much filament moves through the heatsink at a rate. The specific numbers (mm/s) are somewhat irrelevant. The fact is this correlation exists for every type of hotend/speed combination.

There's also another factor that is even more challenging to isolate which is filament glass transition and melting point (2 different temperatures). Technically speaking, these temperatures are not the same across all filament materials. IE, Red PLA from one manufacturer will almost certainly have a different melting point from another manufacturer. This means that the jam risk factor can simply be higher based on choosing a different filament.

Generally speaking, the higher the heat travels above the heater block, the higher the risk of filament jams. While I love the ease of printing with PLA, it has proven to be a little more challenging when trying to print higher quality (slower speed) prints. These are the times that i've most often experienced filament jams of this type.

Also, don't overlook retraction settings. This can be a less than obvious factor as well. The higher the retraction distance and the frequency of how often retraction occurs, can significantly contribute to this prob. Recall, retraction is pulling the already filament back up toward the heat sink. The higher the filament that has hit the glass transition temperature, the greater the chance of it jamming in the heatsink. Example: the combination of a slower print speed and high retraction distance can lead to a jam. It's entirely possible that without changing any retraction settings, a simple increase in speed can eliminate the risk. Conversely, reducing the retraction distance from .8mm to .4 or .2mm may also eliminate the jams. As you can see, there are a variety of 'levers' you can pull in order to change the risk factor of jamming.

One last factor is airflow across the heatsink. In most cases, this may be difficult to alter as the fans on heatsinks are generally fixed speeds and yield a static cooling effect at all times. This is at least in part, why you find quite a few heat sink fan shroud designs.

Sorry to be long-winded. I hope this helps some of you. Here's Lulzbot's extensive reference to 3d Print filament if any of you are interested in reading. https://devel.lulzbot.com/filament/.
Hotend diagram (1).png
Last edited by paulmorley on Tue Mar 21, 2017 4:51 pm, edited 1 time in total.

nopick
Posts: 1029
Joined: Mon Sep 09, 2013 11:14 am

Re: Heat Creep on Taz 6 Single Extruder 2.1 - anyone else?

Post by nopick » Mon Mar 20, 2017 7:59 pm

The tube I cut is one inch long with a bevel at the top. It could be a little longer to keep the top closer to the hobbed bolt.
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paulmorley
Posts: 48
Joined: Tue May 05, 2015 8:28 pm

Re: Heat Creep on Taz 6 Single Extruder 2.1 - anyone else?

Post by paulmorley » Mon Mar 20, 2017 9:45 pm

That's really interesting nopick. Do you swap it in and out whenever you want to use the 1.75 filament? The method is loosely like the flexystruder however, the ptfe tubing isn't intended to be removed.

I just ended up building my own toolhead by buying the parts from i-t-w.com as they sell the hexagon hotend with an actual 1.75 heat sink tube with heat cartridge and thermister for $40. I like putting stuff together so this made sense for me. You definitely have to buy some other parts to go along with it but they sell that as well. In the end, I think you can get all the parts for between $80-$100.

I know, i know. I'm a Lulzbot fanboy and a toolhead glutton. But I built every one myself over time for a fraction of the cost. In fact, my Taz is an upgraded Taz4 that I wouldn't part with for anything. It has upgraded 12mm horizontal bars, upgraded PEI bed, Custom box and 4 toolheads. (Dual extruder v2, flexistruder, and a 1.75 and 3mm V2 toolhead.
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InfiniteGinger
Posts: 31
Joined: Sun Feb 19, 2017 8:01 pm

Re: Heat Creep on Taz 6 Single Extruder 2.1 - anyone else?

Post by InfiniteGinger » Mon Mar 20, 2017 9:56 pm

Did you switch to hardened rods and lmu12 metal bearings? Just read your thread about your taz 4... and wondering if maybe the upgrade is worth it


OP: try recalibrating your esteps. Follow the lulzbot guide except for the extrusion speed. Reduce it to 40. at 100 it's possible to count skipped steps from the back pressure created by the fast extruding. 40 is closer to what your print puts out during printing. Found this worked for me on the same toolhead. My esteps from the factory were a little high.

paulmorley
Posts: 48
Joined: Tue May 05, 2015 8:28 pm

Re: Heat Creep on Taz 6 Single Extruder 2.1 - anyone else?

Post by paulmorley » Tue Mar 21, 2017 7:59 am

@InfiniteGinger
I stuck with the Igus bearings (new set). I know many don't like but I still feel they are a superior bearing when all of the tolerances are right. They require no maintenance and are virtually silent (relative to the rest of the printer). I got the rods from i-t-w.com when the 6 first came out. They had a bunch of 2nd X-axis assemblies so I grabbed one just for the rods. Definitely a good upgrade for me as my dual extruder was weighing down the original rods.

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