Actuator
Cheap and easy to build with stock parts and the help of a 3d printer.
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
- 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
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let's start with the most tricky part of the hardware assembly
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lubricate inserts with oil
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carefully screw in the M8 thread inserts into the aluminium profile
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inserts need to be as perpendicular as possible!
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lots of torque will be required to screw in the inserts
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cut M12 threads into the aluminium profile if the required torque is too much
- 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
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
- 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
- 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
- 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
