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9403Re: converting inkjet printer into 3D printer

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  • raiorz
    Jun 5, 2014
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      @Karthik, it is very simple to hack a HP Desktop with DC motors and encoder.
      You dont need a microcontroller nor step or other motor, you just need one single ralais (with multiple contacts) and two endswitchs.

      The trick is this:
      Remove the original HP paper feed motor-gearbox-encoder-unit, mount it on a new, fix position at the (not moving) frame of your 3D printer and connect a belden drive to move the printer-unit, like this:

      http://s551.photobucket.com/user/rai3dp/media/homemade3DP/Bild110_800x800_100KB.jpg.html

      The belden drive gear should have the same translation like the original gear to have the same "paper" moving translation (if not you must scale your image).
      This unit will move the printer unit back and forth, only with the original printer electronic...

      To do this, you must remove the paper sensor from the original place.
      I remove it to a place that it can "read" a "paper size long" plastic angle profile mounted on the back wall of my printer. 
      Also i mount 2 end-switches at the same back wall, one as a ON contact at the end position and one as a OFF contact at the start position.
      Here you can see (on the right side) one end switch (end position) and the white plastic-angle-profile:

      http://s551.photobucket.com/user/rai3dp/media/homemade3DP/Bild031_800x800_100KB.jpg.html

      http://s551.photobucket.com/user/rai3dp/media/homemade3DP/Bild020_800x800_100KB.jpg.html

      The relais must have multiple (change over) contacts.
      The ON end switch at end position switch the relay on, and with one contact of the relais it hold, till the OFF switch at start position is achieved.
      (With another contact of the relay you can switch the roller drive on.)
      The other contacts are for switching the printer-drive backward. This need 4 (change over) contacts:
      One pair to interchange the two motor cables, to reverse the direction of rotation.
      The other pair
      interchange the two outputs of the rotation encoder.
      This means that not only the motor rotation direction changed, also the the encoder output direction change, so the original printer driver "
      believes" that there is no direction changes.

      To do a full printing prozess of one layer i send (at least) two pages to the printer:
      First the image of the printed part (this is the original,
      forth, printing direction), than just a blank page (this is the back moving direction)
      (for more ink, i print the same layer 2 times).

      I have fond that most HP printes have round 100mm movement before the page begin, and another round 100mm at the end of a page.
      So my 3d printer have space before and behind the print bed. 

      With this described hack my printer do this after i send a image page ( plus a blank page):
      Before the printer start printing it move forward. After round 120mm it "see" a plastic angle profile and "think" this is paper.
      So it have a syc. ponit and print the image each time from same start position.
      At the end of the powder platform, also the angle profile ended and the printer "think" paper ended.
      From this point the printer run normaly another round 100mm before it would stop.
      But it dont stop, because there is my second, blank page.
      So the printer go on (think it have a new, blank paper), but..., in the meantime it reached the end-switch.
      This end switch switch the relay on and from this point the printer run backward.
      Also this time the roller drive run (for powder) untill the printer is in home position, where the start switch is and the printer stop while he "only think" the
      second page is finish.

      Note: while the relais is switches the printer electronic can / will lost some encoder pulses, but wherever, after that the paper sensor "see" the angle profile and so it have a new sync point.

      Other topict, head cleaning:
      You should have the whole head cleaning unit at original place. It mean that the whole cleaning unit will move with the printer unit.
      Behind the build chamber is space for it. In this way cleaning procedure will work in all cases.
       
      I hope this will help a little,

      Ray

      PS: I have a very big problem with this Yahoo group webside. I wrote more posts with descriptions of my 3D printers here, i think it was early 2009.
      And now i played around 2 hours, but for me it is impossible to search, find and view this webside in a usefull way. Thats the reason why i dont write anymore here...
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