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Tuesday, April 30, 2013

Replacing the Ceramic Tape on the Heater Block

It's time to fix the ceramic tape. No patch job this time.

There is embarrassingly little written up on how to do this properly. The best I could find was a PDF on how to assemble the Mk7. In the end I managed but I made a lot of mistakes along the way. And sometimes the point of a tutorial is so that you don't have to repeat my mistakes. But I'm not about to let all my hard mistakes go to waste. So let's start with the don't list:
If you see this, you've gone too far
You don't need to disassemble the whole thing. I thought I needed to get at the bolt that holds the heater block from above. You don't. I thought I needed to get at the nut that's between the block and thermal barrier. There is absolutely no reason to do that. Besides which doing so demands heating up the extruder head periodically so the cold plastic inside them releases the parts. I burned my hands several times.

However, there is a problem. With a dual extruder there is no way to remove the heater block without disassembling it a little. I have no idea how it's done in assembly, but for dis assembly follow these steps:
  1. Put this off for as long as possible. Seriously, this sucks. If you don't absolutely have to do this don't do it.
  2. Heat up the extruder and remove the nozzle with a socket wrench.
  3. Turn off the Makerbot.
  4. Remove the Extruder assembly to improve access to the extruder heads.
  5. On the bottom of the heater block beneath the heater element there is a teeny, tiny screw. (See picture above) This screw is not only small it's short.
  6. Give this screw a 1/4 turn. Do not unscrew it all the way. If you unscrew it too far do not drop it. If you drop be pray someone around you has excellent eyes. (Thank you, Honey. Love you.)
  7. With a pair of needle nosed pliers remove the heater elements. (See picture below)
  8. Move the thermostat wire in front of the heater block. Unscrew the thermostat wire and remove it.
  9. If you have two extruders and you're doing them both be sure to twist-tie the thermostat to the heater element and keep track of left and right.
  10. With a box wrench around the heater block untwist and remove the heater block.
  11. With the block removed replace the ceramic tape. (see PDF, page 23)
  12. Reattach the nozzle.
  13. Reassemble the block.
  14. Reinsert the heater element.
  15. Retighten the teeny, tiny screw.
  16. Reattach the thermostat.
I am extremely glad to see that the latest makerbot extruder wraps the ceramic tape laterally. Hopefully 2X users will never have to go through this. I considered getting some heat resistant duct tape and using it instead of the Kapton, but decided against it because it would increase the thickness of the block. Since I had disassembled everything I accidentally put the heater elements in the wrong nozzle, but it was an easy fix. Then I had to re-level my print heads and build plat. So for now I should be back up and running for a while.

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