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Actuator

saxxon66 edited this page Sep 29, 2018 · 8 revisions

Main Goal

Cheap and easy to build with stock parts and the help of a 3d printer.

Parts list

from top to bottom:

  • servo motor
  • shaft coupling
  • motor mount
  • fixed bearing mount
  • fixed bearing
  • O-ring
  • bump stop
  • ball nut
  • slider
  • ball screw
  • linear bearing mount
  • linear bearing
  • hollow shaft
  • foot

Assembly

0) clean the hollow shaft

  • the hardened steel hollow shaft is grinded to its precise diameter
  • there are remains of the abrasive material inside the shaft which needs to be cleaned properly

1) M8 thread inserts

  • let's start with the most tricky part of the hardware assembly

  • lubricate inserts with oil

  • carefully screw in the M8 thread inserts into the aluminium profile

  • inserts need to be as perpendicular as possible!

  • lots of torque will be required to screw in the inserts

  • cut M12 threads into the aluminium profile if the required torque is too much

2) grease nipple (optional)

  • screw in the grease nipple into the ball nut
  • this is the last chance to fill up the nut with bearing grease using a grease gun

3) ball screw

do not remove the ball nut from the ball screw at any point!

  • slide the bump stop, o-ring and fixed bearing onto the ball screw
  • check orientations of the parts as per the picture

  • to tighten the fixed bearing nut, clamp the ball screw in a vise
  • drop a bit of screw lock on the thread
  • tighten the nut as strong as possible - without the fixed bearing to get stuck
  • use the worm screw to secure the nut

  • attach the slider to the ball nut

4) aluminium profile mounts

  • bolt the fixed bearing to its 3d-printed mount

  • attach the linear bearing mount loosely - do not tighten the bolts yet

  • attach the linear bearing loosely - do not tighten the bolts yet

5) close the internals

  • insert the hollow shaft into the slider
  • use a layer of masking tape to adjust the gap
  • shaft should stick a little bit

  • lubricate the linear bearing with grease
  • turn the slider near the end of the ball screw (extended position) - yet not too far!
  • put the top assembly into the aluminium profile all the way through
  • now tighten the linear bearing and its mount

  • turn the ball screw so that the actuator pulls the shaft inside
  • a screw driver is recommended - or use the shaft coupling (next step) now

  • now tighten the fixed bearing mount properly

6) attach servo motor

  • remove the key from the motor shaft using a M3 screw
  • push the coupling onto the ball screw shaft
  • position the coupling roughly to the fixed bearing mount top surface
  • tighten the ball screw side of the coupling

  • turn the coupling so that the motor mount slot hole gives access to the screw
  • attach motor mount and servo motor temporarily
  • tighten the motor side of the coupling

  • remove motor and its mount to properly tighten the coupling

actuator assembly done

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