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dbusey

PEEK or Poke

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Ultimaker and toxic fumes equals dead canary! So, do we now have to operate our Ultimakers under a hood? This morning when I was attempting to print another component for printer head upgrade, I noticed that smoke began to pour from the brass nozzle of the print head. I canceled the print and at the same time I noticed that the aluminum block with the brass nozzle was sagging a little to the right. I used my pallet knife to put slight pressure on the aluminum block and it freely came loose from the PEEK insulator. I turned the print head fan on, and the exhaust fan to remove any fumes and by this time, there were plenty! The print head is just hanging there with a temp reading that is slowing falling, after two hours it is around 86 degrees. About 20 minutes after the incident, I noticed that Henry (Sir Poop-a-lot) our 10 year old song bird in his cage with his feet in the air!

What failed?

Did the thermocouple fail? The reading never reached 220.

Did the PEEK insulator that the brass nozzle screws into fail? I’ve had the temperature reach upwards of 350 before.

What do I need to reorder? And should I get six of them?

PS. Be sure to get a canary to keep in your print shop!

 

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I believe the peek part can handle at least 300C so you were probably at least 10C over that.

The problem is of course in your temperature measurement. Something wrong with the thermocouple, or the tiny amplifier board on the print head or the wiring somewhere.

I would first try the wiring as that breaks often - simply swap to the alternate wiring that goes to the print head and to the UM board. Heat it back up and see if it is heating to the proper temp now (maybe heat to 95C and make sure it doesn't boil water? or maybe you have a good temp probe). I would try to fix this before ordering anything so you can order all needed parts at once.

If it is still getting too hot I would very carefully take out the thermocouple and examine it.

 

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I am sorry to hear about your Sir poop-a-lot.

Do you remember if the blue led was on when you were printing?

If this wasn't the case, that means your signal cable was disconnected, and no temperature reading could be done.

Hence the overheating - melting of the peek.

What do you mean by ' I’ve had the temperature reach upwards of 350 before.'? Did you have temperature troubles before, or did you manually heat it to this temperature before, without trouble/error-messages?

 

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PEEK becomes structurally fairly unviable much above 260 Deg C. It might be 300+ before it decides

to actually phyically break down, but if you are planning on being well above 260 you need to consider a new material.

I agree with Sander that you should stop all printing at the first sign of unexpected temp behavior and investigate

before you do anything else. If you ever saw 350 appearing on the Ultimaker display...this is basically

the equivalent of all the lights flashing red and sirens coming on.

On a safety front, I personally would like to see a dual thermocouple system with a logic circuit to disengage the

whole PSU when either deviates by more than 20 Deg C from the other. I dont think it would ever be needed

by 98% of users...but perhaps such a thing (or similar) could be put into the next electrical developements step at UM ? (and perhaps the 2% who would need it might be happier)

C.

 

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Gr5 – Sounds like a very good plan of action. A superficial check of the wiring has revealed nothing broken or loose. I have printed a new enclosure for the print-head; so I was planning on taking it apart anyway and this will be a good time to clean and check everything. This alternative wiring that goes to the print head, I was puzzled about it during construction and I still am. Just what is the purpose of the alternative wiring? I like the boiling water test! And this may be a new use for the printer; when we are not printing we could make some tea! Thank you for your feedback, very helpful.

SandervG - Yes, Ruth (my wife) said, “I’m sure going to miss Henry.” He was a good little bird; but think about it, he sang all those years and never once did he attract a mate!

Yes, the blue light was on. What does that mean other than the signal cable disconnect?

Yes, I did get error messages; something like ‘maxtemp’. This was early on, right after construction and during some of the test runs. I would turn the Ultimaker off and let everything cool down, check a few things and then give it another test run. I was able to correct a few problems and learn more of just how everything works on this marvelous little unit. It is quite a wonder! Thank you for your feedback.

C – Well, in this case I wasn’t planning on going above 220. So, when I noticed the smoke and the smell, I first thought that the blue tape was reacting to the heated PLA. When I discovered that the tape wasn’t the problem, I then thought that the Acryllic Build Platform beneath the tape was somehow reacting to the heated PLA. That wasn’t the case either; the smoke flowing from the nozzle became visible when it hit the tape and Build Platform. And that is when I realized that the problem was in the print head itself. Also, it was then that I noticed that the aluminum block with the brass nozzle was sagging a little to the right. Flashing red lights and sirens, that’s a good idea; but, the reactions may still be like mine – What do I do?

Safety, sooner or later will come to figure in the design of these units and redundancy is always the best and most successful route. Also, since we have a USB connection why not have a diagnostic program that could check all of the variables and provide a report with detected issues and suggestions on how to address them? Maybe down the road! Thank you for your feedback.

 

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Just what is the purpose of the alternative wiring

 

It's for a second nozzle if you upgrade to dual print head. But you can use the second set of connectors in place of the first set to verify an intermittent wiring issue.

The Marlin firmware has several tests built in to detect faulty wiring (and halt printing) but sometimes it still gets fooled.

Ultimaker has done tests to verify that if this happens and the heater is stuck "on" then although you will damage the Ultimaker you won't start a fire. You *might* start a fire but it wasn't a problem for the people at Ultimaker.

 

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