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J-Head MkV-B Plastic Parts

Posted by SuperNerd42 
J-Head MkV-B Plastic Parts
July 29, 2014 09:34PM
Well, I finally finished building my Prusa i3. I was attempting to do a few "air prints" with the machine to work out a few kinks with Pronterface on my host machine. To make a long story short, my thermistor came unattached and the nozzle of my J-head Mk V-B hotend melted apart. I have attached a photograph of the aftermath of the incident.

My question is: Is this salvageable? If so, how? If not, is there anywhere I could get just the plastic pieces since the actual nozzle doesn't appear to be damaged?

Thanks, any help is immensely appreciated!
Attachments:
open | download - GEDC0445.JPG (337.3 KB)
Re: J-Head MkV-B Plastic Parts
July 30, 2014 06:25AM
it can be salvaged if the hole dia left behind in the peek is less than the diameter of the brass block. ( been there done that spinning smiley sticking its tongue out .

What you need to do is first clean the brass block of all the remaining plastic.. Then remove everything from the block. Next heat the block on a stove/propane torch/ hot air gun to above 150-200 degrees.. Then carefully screw the block in the peek and move it around till you have it perfectly lined up ( use your eyes to judge it ) ..

i had a similar situation and fixed my j-head .. it is running for over 6 months now. This will not work if the hole left behind is too big.
Re: J-Head MkV-B Plastic Parts
July 30, 2014 07:37AM
Welcome to the J-Head-meltdown-before-it-ever-printed-a-single-item club! Fool me once, shame on you. Fool me twice, shame on me. Just say no to PEEK! After the J-Head meltdown, I bought an all metal E3D and never looked back.....
Re: J-Head MkV-B Plastic Parts
July 30, 2014 12:25PM
Same thing happened to me (home z was too low and pressure grew to high). Thread was not fixable in my case so I drilled little hole in peek and tighten the block within the peek with small screw - similar to the way you tighten the belt pulleys.
Worked for me - I can send a picture once I get home.

Cheers, Larry.


/Larry
(www.filamentshop.ie)
Re: J-Head MkV-B Plastic Parts
July 30, 2014 02:02PM
Thank you all for the replies! Ekaggrat, what would I need to do to clean the plastic off of the nozzle? PEEK doesn't seem to be susceptible to many solvents.

Vreihen, I will definitely be looking at the E3D for my next hot end. It looks a lot more sturdy than hat I have right now.

Filamentshop, I am interested to see how your method worked. Am I understanding correctly in that you installed a set screw to keep the nozzle in place?

Thanks!
Re: J-Head MkV-B Plastic Parts
July 30, 2014 02:39PM
Image attached - it has been leaking a bit, but it has always been leaking, didn't affect prits too much.
You could use ptfe-tape on the heating-block thread and on the screw to seal it a bit - I didn't bother since I've replaced it with e3d v6 soon after.
It did the job in the meantime.
As for cleaning - I used soldering iron, not too hot, just about to make plastic soft, but not liquid and pilers to remove it while still hot.
Good luck!


/Larry
(www.filamentshop.ie)
Attachments:
open | download - 140730-IMG_20140730_185456488c.jpg (67.7 KB)
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