Assembly step 9

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Revision as of 09:25, 27 June 2012 by Admin (Talk | contribs) (User Submitted Notes)

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(click the picture to download the PDF file)

Z-axis Assembly

Step 1

  • Slide the M3 bolts through the z-axis mounting plate
  • Place the 3/4" nylon spacers on top of the mounting plate
  • Bolt the motor to the spacers
    • The thread depth on nema17 motors is notoriously unpredictable. Although datasheets spec 4mm minimum depth, we've run into some that are only 3mm deep and others that exceed 5mm. It's a crap shoot.
    • If you thread depth is shallow, you won't be able to bolt the motor firmly to the spacers. In that case, use an extra M5 washer to make up the space.
1. M3 bolts
2. add 3/4" spacers
3. use M5 washer if necessary
4. bolt on motor

Step 2

This is the only time you will have to measure in the whole assembly process :-)

  • Thread 2 M8 jam nuts onto the end of the M8 threaded rod.
  • When the top jam nut is 5mm-6mm away from the end of the threaded rod, tighten the two nuts together.
  • These nuts give the assembly a place to rest on the bearing, they also provide a positive stop for your z-axis coupler.
1. Thread nuts on
2. measure distance
3. tighten against each other
4. finished step

Step 3

Now it's time to put your two assemblies together.

  • First, slide your coupler through the motor mount hole until it's pushed up on the stepper motor shaft
    • the coupler is transparent blue in the pictures below to help see the motor shaft and threaded rod
  • Your shaft will be just short enough to *not* stick out the end of the coupler, but you'll probably be able to see it
  • Keep note of the orientation of the coupler. one end accepts M8, the other M5. Put the M5 side up first, so the M8 is exposed on the bottom.
  • Slide the assembly from step 2 (threaded rod with two nuts) up through the Motor mount plate.
  • Slide the z-axis bearing onto the rod and press it into the hole of the z-axis mounting plate.
    • this is going to be a little difficult because the bearing is a friction fit inside the hole. Once you get it close, just use your thumbs, or the edge of a work surface to help push it through. Make sure the edge is deburred. Try not to push on the shaft of the stepper motor.
  • While sliding the assemblies together, make sure the M8 threaded rod makes it up to the stepper motor shaft.
  • Once those are lined up, slide the coupler back down until it's resting on the M8 jam nuts.
  • After the coupler is resting on the M8 jam nuts, verify the jam nuts are resting snugly against the bearing.
  • Verify the bearing is flush with the bottom of the motor mount plate. The top of the bearing will be protruding from the top of the motor mount plate. That's OK.
  • Now that everthing is aligned, tighten the coupler
1. Slide coupler up
2. slide assembly up
3. put bearing in place
4. slide coupler down over M8 rod

Here is what your assembly should look like at this point:

(click the picture to download the PDF file)

User Submitted Notes

Note: This is the section to add your own notes pertaining to this sub-assembly) If you run into a problem or find yourself asking a question, please post the solution here to help the next person who has the same problem/question


  • If you have problems pushing the coupler up on the stepper motor shaft just take a knife and clean the edge on the coupler.
  • I found that some delrin came off and created a blockage and I had to screw it in and out several times (I guess I went for 5 to 10 mm each time) to remove the derbies (by blowing in the hole and on the thread) or it would get stuck...
  • My stepper motor shaft was too long, and I ended up only using one of the jam nuts, I used some threadlock and jammed it against the coupler.
  • NOTE: If your Deldrin Nut is stiff and is not easy to move. Use your hand held electric drill and attach it to the short side of the stepper motor shaft that is exposed. Just run it up and down a few times to fix the problem.

NOTE: Need BOM listing for this step.