time to replace the hot end

Discussion in 'OpenBeam Kossel Reprap and OpenBeam Kossel Pro' started by Rick Gordon, Aug 24, 2015.

  1. Rick Gordon

    Rick Gordon Member

    well, I've been considering myself lucky that my original J-Head had been working reliably.
    Tonight, while experimenting with leveling, I typed "G2 Z2" instead of "G1 Z2" and the effector went skittering across the glass, slammed into the X-Z bed clamps, and I quickly shut it down.
    After that, it would do things like G28 and G29 but it would not do a G1 - said "printer error ..."
    Closer inspection - the thermistor wires are broken clean off, and the potting compound holding the thermistor is chipped and broken.
    Now what? Try to repair or move on to K-head? (I don't even know what a K-head is honestly, except that it comes after J.) Will the effector work with it or are modifications required?
  2. grainiac

    grainiac Active Member

    The K-head is designed to be a drop-in replacement for the J-head. So you can't probably do anything wrong by just ordering a K-head. The other option would be to go for another end effector/hotend, e.g. E3Dv6. Have a look at the thread E3Dv6 end effector. I have finished the design on it and it is working in my printer for some weeks now very reliable, btw. way better than the old J-head.
    protoserge likes this.
  3. Rick Gordon

    Rick Gordon Member

    thanks, that's tempting - because I don't know where to find a K-head. The Amazon/Seattleautomationz pages only show a K-head heat sink, w/o a photo.
    If the K-head is a drop-in replacement, and it works, that seems like a preferable option - just because its easier and there's less reconstruction.
    That plus my printer is no-op now - although I do have access to my old Prusa for PLA printing.
    But I like the E3Dv6 - I used the Lite version in the Prusa - so I can see it as an option down the road.
    Right now - where does one the "K-head" hot ends? Weren't there supposed to be J-head to K-head upgrade kits available for early adopters?
  4. grainiac

    grainiac Active Member

    I never got a notification from the OpenBeam Team that there would be a K-head available although I was in the first batch of printers. Anyways I have chosen a different path going with my own E3DV6 end effector and an Azteeg X5 mini controller running SmoothieWare. The experience with the J-Head, Brainwave & Marlin was for my taste a little bit unsatisfying to put it mildly.....
  5. David Boyd

    David Boyd Active Member

    Right now if you want a K-head you need to buy a Full E3Dv6 and then the k-head heat sink and swap it in for the one on the E3Dv6. (NOTE - the E3Dv6 LITE will not work for this).

    Or, just buy a standard J-head nozzle along with a new thermistor and Kapton tape. I forget if the modified J-head with the KP is a Mk V or Mk VI compatible (the difference is in the thread and diameter of the nozzle into the PEEK heat sink).
  6. bytecounter

    bytecounter Member

    If @Mike Ziomkowski is around he'd know more about availability (you can PM/start a conversation to ask). I got one through him. The defining characteristics that made me gravitate toward it vs the full E3D were the pre-applied WS2 coating and pricing -- I don't think you can go wrong with the full E3D/custom effector or K-Head heatsink+E3D parts though. They all seem to have been an improvement over the J-Head.
  7. Rick Gordon

    Rick Gordon Member

    so a K-head is just one of these :

    combined with this "mystery" part:

    I thought the whole point of the E3DV6 metal hot ends was that heat sink. What does the K-head version look like?

    If you use the modified end-effector, do you keep the fan/duct from the E3DV6?

    If I'm going to have to dismantle it to repair, I might as well upgrade it at the same time. I would like to be able to print with higher-temp materials.
    I'm assuming that the use of potting compound means the heater block is not salvageable.
    but really, i only need that block and a new thermistor (and a way to hold it in place) to get it running again.
    I might be able to get one machined locally - but if one is available already...
    I do see some J-head setup's like this: http://www.ebay.com/itm/0-4mm-Nozzl...-Hotend-Bowden-Extruder-Tube-fan/361370150927
    also ones like this (for 2X the price):

    but the latter has a square heater block.
  8. bytecounter

    bytecounter Member

    There are comparison pictures in this thread: http://forums.openbeamusa.com/threads/from-a-j-head-user-first-k-head-thoughts.271/#post-2821

    Video with cross-sectional drawing: http://ztautomations.dozuki.com/Guide/K-Head: Bowden Tube Installation/7

    @Taylor modified the [@grainiac's] effector design to retain the E3Dv6's stock fan setup here, so it is possible: http://forums.openbeamusa.com/threads/e3dv6-end-effector.266/page-2#post-2895

    RE the potting compound on the J-Head, I think there were at least one or two users who managed to take it out with a dremel, so it is possible..
  9. grainiac

    grainiac Active Member

    In both cases using Taylor's or my version of the E3Dv6 end effector you'll need the 30mm fan in a 5V version. The fans coming with the E3D kits are either 12V or 24V. Btw. there is also a 3rd variant of my end effector by @sdriessens! See post #43 of the
    E3Dv6 end effector thread.
  10. Rick Gordon

    Rick Gordon Member

    thanks. I'm going to go with the replacement K-head option for now. That's the simplest path to getting it operational I think. I'll see how that works and go from there.
  11. Rick Gordon

    Rick Gordon Member

    however, after talking to Taylor - I can see the desire to go with the full E3D down the road - for higher-temp materials. Right now, I want to get operational again.
  12. Taylor

    Taylor Moderator Staff Member

    @grainiac Actually, you don't have to use a 5v if you don't want.

    I used a 24v E3D fan and soldered the leads to the effector PCB

    Tough to get a good photo with my phone, but this is how it's running on our machines.

    Attached Files:

  13. Mike Francies

    Mike Francies Member

    Taylor, is the 24v on the effector constantly on or is it controlled from the BW for powering the hotend? I would have thought that there would not be 24v constantly available for the fan.
  14. Taylor

    Taylor Moderator Staff Member

    It's always on. I can't recall, but I think I just connected to the LED +/- pins. It's such a small draw (.01a), that there shouldn't be any noticeable effects on anything.
  15. Mike Francies

    Mike Francies Member

    Thanks, Taylor, I have just got myself an E3D and was wondering about the 24v supply for the fan. Just waiting for the FSR kit - any news on how long it will be?
  16. Taylor

    Taylor Moderator Staff Member

    We're working on it. In the mean time, if anyone would like, you can download the Experimental version of MatterControl that has new 7- and 13- point software delta calibration in it.


    It does not require a probe. In fact, once completed, you can disable G29 completely.

    The 7-point works decently well on the KP out to ~200mm diameter. The 13-point does much better out to the very edges of the bed. It just takes a little bit longer to run through.

    To use it, enable Advanced mode in Mattercontrol Experimental build.

    Then, Settings > Printer > Print Leveling and then select the leveling solution from the drop down menu.

    Once selected, run the Automatic Print Leveling under the Options tab.

    We've found it to have very similar results to the FSRs. The goal is to make it so that it can use the probe on a machine to measure the points in the solution automatically. As it is now, you need a piece of paper and must locate each point manually.

    Feedback much appreciated.
  17. protoserge

    protoserge Member

    Thanks for this information. I had been wondering what exactly a K-head was since it was not coming up on any search results. I was supposed to get a unit at some point months ago (?), but never received one. I assume you got this from Terence directly. Is the K-head the "all-metal" hotend that @Terence Tam had been working on?
  18. Rick Gordon

    Rick Gordon Member

    darn, Mike was quick to send me a K-head to repair/upgrade my printer, but - it seems to be bent a bit and i'm hesitant to try and use it.
    hopefully will get resolved. bummed, as i hoped to get it going by this weekend. fortunately i do have other projects to work on!

    question - i was able to get my J-head apart tonight, and get the old thermistor out (it was pretty seriously chipped up.)
    Anyone know what the specs are for that thermistor?
    Are you just holding it in place with Kapton tape? (kludgey I know but might get me running again in the interim.)
  19. Rick Gordon

    Rick Gordon Member

    one more ping - anyone know what the old thermistor was? Maybe I can get this J-head back together for a little while longer at least.

    (a few minutes later i realized i could look into the firmware to find out, and it uses #5:
    // 5 is 100K thermistor - ATC Semitec 104GT-2 (Used in ParCan & J-Head) (4.7k pullup)
  20. Taylor

    Taylor Moderator Staff Member

    It's the same one the k-head uses... same as E3D too.

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