Having problems with my extruder

[Daniel Porter]

So my extruder will print ok for a while and then it jams.  This started last Saturday.  I noticed that PLA is leaking out from the ceramic housing onto the brass thread.

http://imageshack.us/photo/my-images/689/20130322231836719.jpg/
http://imageshack.us/photo/my-images/42/20130326111844330.jpg/

Notice that the PEEK/PTFE housing sits unflush with the top of the ceramic housing.  This is the way it was given to me at the buildoff but it worked great for two weeks.  I extrude at 170C with the Ultimachine PLA which is the same type we got with our printers.  Settings are pretty much default is slic3r and I have not changed much.

To clean this I use heated DMF and it pretty much restores it to new.  I heat up the ceramic/PEEK/PTFE housing using a hot air gun then squish the PEEK/PTFE flush against a hard surface; this causes PLA to seep out of the crevice that causes the plastic to rise.  Then I wrap the brass thread in PTFE tape (enough to make the connection tight) and screw it as flush as possible to the PTFE insulator.  I have cleaned and redone this thing three times and it keeps leaking. 

Initially I though it was a large heat gradient that was forming a huge molten plug (causing the jam).  So I lowered the fiberglass insulation and blew a fan on the hot end while it printed... no avail. 

You guys have any ideas?  I am going to clean it again tomorrow...

It is worth noting that the tip is not clogged.  After cleaning it extrudes like a dream until the leak happens.

Daniel

 

[Brad Luyster]

According to this guide: http://www.makergear.com/pages/stepper-plastruder-instructions-hot-end-batch-2

It implies that the barrel is not tightened well enough against the nozzle.

Daniel

 

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[Daniel Porter]

Yeah, I read that one.  Been google'n like crazy.  I'm going to try to tighten it a little more and add a generous amount of PTFE tape.  I might try to heat the tape and then do another layer too (to adjust for thermal shrinkage).

Daniel

[Joshua Wilcox]

Be careful with DMF to. It's linked to cancer and birth defects. Some industries have banned women from using it in large scale operations.

Sent from my iPhone

[Daniel Porter]

Yeah, reading the MSDS on DMF was like reading a Stephen King novel.  I use DMF in my research so it is the double bagged gloves, goggles, and fume hood. 

So I think I kind of got it working.  I used a washer between the brustruder and the top of the ceramic barrel to help keep the PEEK/PTFE in place.  Seems to work okay for now but the PEEK/PTFE part pushed up and is bowing my wood plate something fierce.  In case anyone wants to know... removing the PEEK/PTFE part is simple, use magnets to pull the two steel rods out of the sides and push the plastic out from the bottom of the ceramic barrel.  Worked like a charm. 

When I looked at the PEEK part it seems that someone machined it in error and tried to drill the holes twice (over top of each other).  I could correct this by drilling the two holes 90 degrees offset.

I'll keep you guys updated on my failure...

Daniel

[#]

not sure your printing in 3mm or 1.75 mm filament but these work pretty good .    you can get all the parts fairly cheap for it of ebay ,      

  http://www.ebay.com/itm/NEW-MKIV-J-Head-Hot-End-0-4mm-nozzle-1-75mm-filamnet-for-RepRap-3D-Printer-MK4-/230953950656?pt=COMP_Printers&hash=item35c5ed9dc0




  i killed the heating element in mine in a hurry 24/7 use ,, lol     swapped over to the J-head an use a quick change setup now so i can swap out the extruder when switching from abs - pla plastics      kinda good to do ,  cuz if you dont get all the pla out of the hotend when you heat it up for abs it can burn an make a clog , 



also noticed the J-head hotends heater is fast to heat.    
http://www.ebay.com/itm/New-3D-Printer-Reprap-Mendel-Prusa-Heater-Cartridge-12V-40W-for-Hot-End-J-Head-/221168698861?pt=LH_DefaultDomain_0&hash=item337eae85ed

 

[Daniel Porter]

Oh wow Doodler!  That thing looks awesome.... so I bought one just now.  Mwahaha

If it works out with PLA, I will buy another for ABS.  The Makergear one I can tinker with once these come in!

Thanks a ton man.

Daniel

[#]

np,         

   when you switch the  heater  make sure you do a PID calibration  AutoTune command ,    http://www.soliwiki.com/PID_tuning   http://www.make-something.com/?p=123

          didnt see but are you useing 1.75mm filament or 3mm ?  

  

[Daniel Porter]

I use 1.75mm filament.  Might just use it for ABS.  Got a 480 Watt power supply I am going to mod for my Prusa so it will be a good match.  Also bought me some 150mm KaptAn tape.

Thanks for the links.  I will review them thoroughly!

Daniel