User Tools

Site Tools


filament_clog_recovery_1

Clearing a Filament Clog or Breakage - Without Removing the Extruder Head

If you've come to this page, then you are likely dealing with one of a number of filament related failures, and you just want to get up and running again with the minimum of additional grief, so hopefully the information below will be helpful, practical and will get you back into production ASAP.

A few examples of filament clogs and/or breakages

(And how to recover from them without having to remove the extruder head and break out the tools...)

If you see something that looks like the photo below, then you are almost certainly experiencing a filament clog:

chewed_nat_in_capstan_annotated.jpg

So why did this happen??

There are a number of reasons that a filament clog of the nature pictured above could have occurred, as the manner in which different grades, colors and styles of PLA filament (yes, there are enormous variations in the commercially available filaments for desktop FDM machines, and PLA is no exception), and since this section is dedicated to showing you how to recover as quickly and effectively as possible from filament related failures we'll leave the build environment, chemistry and materials science discussions for another section.

The particular failure in the photo above demonstrates not only a clog that has resulted in the stuck section of filament becoming worn down (this can be alleviated to some degree by using the filament monitor feature), but in this case the filament also managed to break off at the ingress point at the optical encoder, which is is at the top of the extruder assembly, leading to a difficult filament clog to recover from (see below):

chewed_nat_and_broken_rotated.jpg

Possible workflow to recover from the clog/breakage pictured above:

1. Manually increase the temperature of the extruder to its PLA maximum of 240ºC

Go to the Control page (select the Control icon from the top right hand section of the Zeus UI), and select the vertical Extruder tab on the left.

By holding down the circular “Heater” button for a several seconds and then releasing, you'll bring up the manual temperature setting dialog box:

Now you can choose to increase the heater temperature by one of two methods:

- By continually pressing on the “+” operator, so that the temperature increases to its maximum

–or–

- By touching the display in the temp readout section (or clicking in this section with a mouse, if you have one connected), you'll bring up this dialog box:

Then you can simply enter the max of 240ºC (which is the max allowable temperature for the PLA-only platform, but of course this will change when the heated bed version of the platform is released).

After you hit the 'ok“ button, you'll still need to hit “Save”, to confirm your selection and tell the Zeus to heat up to that temperature (shouldn't take too long…).

Now wait for the temperature indicator on the controls page to reach the set temperature.

Once you have brought the heater temperature up to its max, it becomes far easier to restore filament flow, via a number of methods that in most cases, will allow you to purge the extruder of the clogged material, recovering quickly from the clog/breakage and hopefully, not need to remove the extruder head from the extruder carriage to clean the head manually

2. Try to pull the filament out of the extruder

Once the extruder has heated up to its maximum temperature, it may still be possible to just remove the filament by manually releasing the tension on the capstan/pinch roller mechanism (you do this by pushing down on the spring arm to the right).

If the failure is not as severe as the one pictured above, and the filament has not broken off at the ingress point, then you'll have a fair bit of filament to grip onto. If the filament has indeed broken off at the optical encoder ingress point, then you'll need to use a set of small needlenose pliers (always a good thing to have around anyway…).

If you are successful in pulling the filament out in this manner, that's great, but there is still the likelihood of additional filament residue in the extruder tube, which will require that you purge the extruder head further in order to get it to start flowing again.

3. Purge the extruder head to clear excess filament residue

There are a few ways to purge the extruder head:

3a. Much of the time, it's possible to use some fresh filament to manually purge the extruder tube and nozzle. By pressing down on the spring arm, you may be able to push new filament through and get the required flow. If that's the case, be sure to to push a fair bit through just to be certain that the system is flowing properly, and then you should be ready to resume production.

If the case will be such that the filament is both clogged in the extruder tube, and broken at the main ingress point (as pictured above), then it becomes necessary to use a high-quality set of small needlenose pliers, or an industrial/surgical tweezer or clamp to grip the remaining filament “stub”.

Video tutorial for procedure 3a (coming soon)

But let's face it, scenario 3a is a bit to easy, and few clog recoveries will be that simple…

3b. More often, with clogs of the nature described here, you may be able to easily remove the accessible portions of the filament, but will have significant difficulty getting new filament to flow if you're only using a new section of fresh filament. In this case, molten or partially softened filament is still stuck in the stainless steel extruder tube, and you'll need to use something more rigid to force the softened filament down far enough to restore proper flow.

What to use and how far can one “plunge” without compromising the PTFE sleeve?

The picture below shows a 2.0mm diameter length of carbon fiber rod being inserted into the extruder head, following the same path that the filament would follow. Lengths of carbon fiber rod in 2.0mm diameter can be purchased easily from any hobby shop, or online from any site that caters to RC car, boat, plane enthusiasts; it's pretty common stuff (note: It's also available in 1.5mm diameter, which is also handy to have around sometimes).

2.0mm_cf_rod_1_annotated.jpg

If you don't have any 2.0mm diameter carbon fiber rod handy (email us if you need to know where to get some, but ebay is always a safe bet…), you can usually get almost the same results by straightening out a “jumbo” (1.75” in length) paper clip, and carefully using that. The wire gauge of a jumbo paper clip is usually only 0.05“/1.27mm, so it won't be as effective, but just about everyone has a jumbo paper clip lying around.

Video tutorial for procedure 3b (coming soon)

And what's all this about a “PTFE sleeve”?

Inside the extruder head is a very cleverly designed, milled stainless steel tube that looks like….well, it looks just like this:

extruder_tube_2_flipped_cropped.jpeg

Okay, confused yet?? Hope not, but it's important for us to provide a fair amount of detail.

Yes, we're working on a video to accompany this procedure, which will be coming soon too.

Here's another picture of the 2.0mm diameter carbon fiber rod being used to purge the breech and upper portion of the stainless steel extruder tube:

cf_rod_as_plunger_5_rotated.jpg

Anyway, the point here is that with a little bit of understanding, and the right tool (a length of 2.0mm diameter carbon fiber or steel rod, or even a jumbo paper clip), it's often possible to quickly and effectively recover from a filament clog, or breakage without having to remove the extruder head and swap it out for a spare.

And there's one more scenario worth covering as long as we're at it…

3c. The two scenarios described above don't take into account what to do if you can't remove the upper portion of the stuck filament very easily. If the filament has been compromised by excessive friction from the knurled capstan, like this:

chewed_nat._in_capstan_5_cu_shows.jpg

And there's not enough material remaining to be effectively pushed down by the method described in 3b, then it be necessary to use a needlenose pliers to pull the filament out as pictured below:

needlenose_grabbing_from_extruder_tube.jpg

Video tutorial for procedure 3c (coming soon)

Which will result most of the time in something like this:

needlenose_success_piece_removed.jpg

And now you can use the technique described in 3b to purge the extruder tube and hopefully resume production without excessive delay.

What to do if none of the techniques described here don't produce the desired results

If the methods described above don't restore sufficient filament flow, then chances are you'll need to remove the extruder head and clean it manually

In the event of a more severe filament clog

To navigate to the section on manually cleaning the extruder head, click on the link below:

Clearing a filament clog by removing the extruder head and manually cleaning it

filament_clog_recovery_1.txt · Last modified: 2017/02/08 21:26 by navigating21