Cupcake Calibration

This page is part of the CupCake CNC build sequence.

Cupcake Calibration

Now that all the pieces are together, time to get things calibrated for optimal performance!

Axes - Mechanical

X and Y - Mechanical

  1. Kits from MakerBot Industries ship with precision ground rods with a 10-micron finish that do not need to be smoothed at all. If you are supplying your own rods, you want them to be very smooth. Sand the rod supports down with some 300 or 400 grit sandpaper and then rub them with super super superfine steel wool
    • Shops specializing in auto body repair carry very fine sandpaper
  2. Apply 3-in-1 oil to rod supports
  3. Move the Z stage down until the printhead almost touches the build platform. Then slowly (manually) move the build platform along both X and Y axis while observing the distance between build platform and print head. It should remain constant. If does not, your X and/or Y axis are not exactly parallel to the build platform. Check and make sure none of the tabs or magnets or other lumps are sticking out of the top of the Y stage or bottom of the build platform. Push them in or shave them off with the supplied razor blade as appropriate. If it still isn't level, you can level it out by attaching some electrical tape to the bottom of the build platform (or to the top of the Y stage).
  4. Check the tension on the X and Y platform belts. If they are too loose, the teeth will slip on the motor pulley. If they are too tight, the machine will suffer from excess vibration and acoustic noise.

Z - Mechanical

  1. Check each threaded rod for vertical (up/down) movement (too loose) or stiff movement (too tight). For each loose/tight threaded rod:
    1. Remove the pulley
      • Confirm that the rod is still loose or tight.
      • If the rod feels okay now, perhaps the pulley was too loose or too close to the bolt-heads underneath
    2. Undo the top Z Stage Bracket bolts
    3. Remove the Z Stage Bracket
    4. Loosen the two M8 nuts clamping the bearing in place.
    5. Raise the top M8 nut up a few mm and drop the bottom M8 nut so the bearing's top edge sits about 1mm below the cupcake top surface.
    6. Put the Z Stage Bracket back in place. Don't attach any M3 nuts yet!
    7. With one hand on top, firmly hold Z Stage Bracket down and use a finger to stop the threaded rod from rotating
    8. With the other hand underneath, slowly raise the bottom M8 nut until you just feel the bearing meet the bottom of the Z Stage Bracket.
    9. Keep the bottom M8 nut stationary on the threaded rod, remove the Z Stage Bracket and finger-tighten the top M8 nut back down until the bearing is firmly clamped.
    10. Wrench-tighten the M8 nuts so the bearing is well clamped
    11. Put the Z Stage Bracket back on and bolt it in place with the M3 nuts.
    12. Put the the pulley back on - check for M3 bolt-head clearance
    13. Check that the threaded rod turns smoothly and there's no vertical (up/down) movement.
  2. Set all corners of the extruder platform to the same height
    1. Find a straight edge, such as a ruler.
    2. Place the straight edge flat on the platform at one corner such that the edge sits next to reference marks on the cupcake's frame.
    3. Pick a reference mark
    4. Lift the platform and adjust the nut's height so the straight edge lines up precisely with the reference mark
    5. Repeat for the other three other corners using the same relative reference mark as the first.
  3. Apply 3-in-1 oil to threaded rod supports
  4. For cupcake's with side-mounted circuit boards, check for clearance between the extruder platform and the backs of the bolts poking through. Add washers to the other side as required to make more clearance.

End Stops

  1. With the machine powered on, put something inside the optical sensor of each end stop. Check that the LED on the end stop board lights up.

Axes - Electrical

X and Y - Electrical

  1. Check stepper motor direction
    1. Position platform at X and Y axis mid-points
    2. Launch ReplicatorG
    3. Launch Control Panel
    4. Set step size to 5mm or smaller
    5. Click X+
      • Facing the Makerbot front panel, did the build platform move left?
      • If yes, great!
      • If opposite direction, either
        • Unplug the X-axis motor connector and plug it in upside down.[Be sure to power off to avoid damage to the stepper driver], or
        • Invert the direction in software (ReplicatorG v006 and up)— see Machine -> Motherboard Onboard Preferences and check Invert X Axis
      • If it didn't move at all, check all your connections (link to general electrical debugging reference)
    6. Click Y+
      • Facing the Makerbot front panel, did the build platform move toward you?
      • If yes, great!
      • If opposite direction, either
        • Unplug the Y-axis motor connector and plug it in upside down.[Be sure to power off to avoid damage to the stepper driver], or
        • Invert the direction in software (ReplicatorG v006 and up)— see Machine -> Motherboard Onboard Preferences and check Invert Y axis.
      • If it didn't move at all, check all your connections (link to general electrical debugging reference)

Z - Electrical

  1. Manually position the Z-axis in the middle of the bot by pulling the belt before testing.
  2. Set the step size to 1mm or smaller! (Some (very) old versions of the firmware had the bot defaulting to inches rather than millimeters. Even if this has happened to you, a 1mm step size will only move the bot an inch.)
  3. Click Z+
    • If the platform moves up by a barely-perceptible amount, you're good!
    • If the platform moves down, unplug the Z axis motor connector and plug it in upside down.[Be sure to power off to avoid damage to the stepper driver]
    • If the platform moves a long way up or down, update your firmware.
  4. Once the 1mm stepping appears to be working, set the step size to 5mm and alternate between Z+ and Z-.
    • If the platform moves by a barely-perceptible amount:
      • Confirm that nothing is blocking the movement by turning the stepper gear manually (may need to disable stepper motors from the control panel first)
      • On the Z Axis Stepper Driver board, turn the pot about a quarter-turn clockwise and try again - this increases the amount of current supplied to the stepper motor.
    • If the Z Axis Stepper Driver IC is getting very hot (don't burn your finger!):
      • Turn the pot about a quarter-turn counter-clockwise and try again.

End Stops - Electrical

  1. Center each axis.
  2. Set the step size to a large amount (20-50mm)
  3. For both directions in each axis, set the axis moving, then trip the endstop in that direction.
  4. If the movement isn't stopped immediately, reverse the endstop connections on the appropriate stepper board.

Extruder - Mechanical

  1. add detail about idler wheel positioning, failure modes, etc.
  2. add detail about PTFE/threaded rod alignment, cleaning, etc.

Extruder - Electrical

  1. add thermistor checks
  2. add heater checks

Extruder - Thermal

  1. add checks for ABS temperature/lubricity, feed rate, etc.

Test Prints

  1. add raft adhesion check
  2. add small object print test (e.g. makerbot coin)
  3. add tall object print test
  4. add wide object print test and platform flatness test
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