Some DON'Ts With the Cube

All of the glowing reviews I have posted about the Cube 3D printer are true,  The quality of the prints has been remarkable.  But, that does NOT mean that I have not been able to bring it to its knees.

And, by doing so, have made it less likely that you will end up doing so.

Remember when I ran out of filament?  It happened when I was running it unattended.  And, the reason it happened is that I failed to read the warning that came up on the LCD about not having enough material to complete the object as I was starting it..  I saw something; but, because I intended to photograph the piece for a stop-motion movie, I'd flooded it with lights.  And, since I wasn't wearing my reading glasses, the brightness made it difficult to decipher.

I should have taken the time to go get my glasses.  Therefore, the print never completed and the filament ran completely out.

I didn't think much of it and it took some time to obtain more filament.  But, when I tried to load the new filament into the PrintJet I heard an all too familiar sound.  In a 3D extrusion printer, if the extruder cannot move the filament forward, it makes a clicking sound.  Virtually, all owners of 3D printers have heard it at some time or other.  More often than not it means the print head is clogged.  And, that was true for the clicking I was hearing from the Cube PrintJet.

I'm pretty fearless when it comes to tackling mechanical problems.  So, I took off the Printjet cover to see if I could clear the clog.  This drawing is my simple rendition of the extrusion system used in the Cube.

Cube Extrusion System

As you can see, there are three basic parts:

1. A top tube into which the filament is loaded
2. A gear and spring-loaded idler that pull the filament
3. A bottom tube which is heated to extrude the filament.  

As you can plainly see, this is a brilliant design allowing for a nice small Printjet with direct contact with the filament.   It allows them to put a motor, fan and extruder into a nice, compact Printjet package.  The compactness of the design is wonderful; but, it does mean that it is difficult to reach material that has gone past the gear.

In fact, this is exactly what I found.  The filament end had gone past the gear and was stuck in the bottom tube.  There was just the slightest piece of filament in the gap between the lower tube and the gear.  But, I could not get to it.  I returned it to the factory and they replaced the Printjet.

The problem was that by ignoring the warnings on the LCD, I had allowed the filament to run out and go past the gears as it ran unattended.  Had any part of the filament been sticking up from the Printjet, it could have been easily cleared.

The outcome of my experience was that 3D Systems redesigned the cartridge by attaching a small clip to the tail end of the filament so that if a user fails to heed the warning that there is not enough filament to complete a print job, the clip will keep the end of the filament from going past the gears, allowing the user to back the filament left inside the Printjet out.  Sometimes manufacturers have to go out of their way to save us from ourselves!

If that were the ONLY way a user could clog the Printjet all would be well.  But, I found out this weekend that it is not.

This past weekend, I was in Wilmington, DE for a few days visiting my granddaughters.  Just before I left for the trip, part of my filament order came in and among the colors was magenta.  I'd taken the Cube along for the ride and decided to make something for my granddaughters in magenta.  This, of course, required removing the old cartridge to make way for the new.

Impatience was the problem.  I made the mistake of trying to "help" the Cube back the old filament out of the PrintJet.  I apparently pulled too hard causing some of the filament to remain in the bottom tube.  Not good.  I learned something new...

LET THE CUBE REVERSE THE FILAMENT WITHOUT HELP.  ONLY PULL ON THE FILAMENT AFTER THE GEARS STOP TURNING.

Putting the new filament into the Cube, I heard that dreaded clicking sound.  Once again, I'd clogged the head.

But, this time I wasn't 15 minutes from the factory and I wanted to make that magenta object for my granddaughters.  So, I came up with a last ditch effort to solve my problem.  Knowing there was a hobby shop near the hotel, I ran out and purchased the thinnest piano wire they carried.  (Piano wire is commonly used in Remote Control airplanes.)

Before going any farther, I need to warn you that 3D Systems is NOT going to like what I did.  The Print Head of the Cube is around 240C degrees and that is MORE than hot enough to cause serious burns.  And, I am not telling you what I did so that you can do the same.  I'm only relating my experience to say that I was able to get up and running again without having to send my Cube back to the factory.

As I mentioned earlier, I'm pretty fearless when it comes to tackling mechanical problems.  So, using a piece of .piano wire with a diameter of 015" (.38mm), I was able to clear the clog and get on with the business of printing.

My method was to start the "Change Cartridge" process which heats the print head.  The .38mm wire was small enough to insert into the hole at the bottom of the heated print head.  As the filament in the bottom tube melted, I put slight back pressure on it until it moved back up the tube and out.

I didn't have tools to remove the cover of the Printjet.  So, I don't know if the plastic was caught by the gear and pulled out or simply fell out of the bottom tube.  Whatever the case, the outcome was that I was easily able to get up and running again.

The bottom line is that we need to be careful that we don't do something that causes filament material to be left in the bottom tube of the Cube.  I have reported my latest experience to 3D Systems along with a suggestion that the nozzle of the Cube be redesigned so that it can be unscrewed by the user so that a clog could be removed from the top of the print head with simple tools.

Now, lest you think that the potential for clogging is limited to the Cube.  Let me correct that notion with this link to a technical bulletin for an HP extrusion printer that costs over $15,000 US!   And, there are numerous posts about Makerbot clogs.  Just go to Google and enter "Makerbot Clog" to see just how many hits you find.

It happens.  But, as the community of Cube users stumbles across actions that contribute to clogging, we can learn how to avoid those actions.  And, that is what sites like this are all about.

Both instances I have had with clogging were caused by user error.  Even so, 3D Systems immediately responded by coming up with a solution to make sure future users would not run into the problem when coming to the end of the filament. 

In the case of the latter clog, I was up and running in little more time than it took me to drive to a hobby shop and back.  This is an image of the piece that I printed for my granddaughters AFTER the clog was cleared.

Vase - Fire (Magenta)

You don't have to stay home to use the Cube!