Actuator assembly

While it might seem daunting putting the Actuators together is relatively easy with only a few basic tools required. You can see videos at the end of this page for how these go together.

• Allen keys
• A file to get rid of any aluminium burrs
• Optional Impact Driver/Cordless drill
• Loctite
• Adjustable wrench/spanners for fixed bearing nut

Below is a parts diagram of the Actuator, it will make assembly easier if you familiarise yourself with the names of the components

• 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

1. 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

2.M8 Thread inserts

Let’s start with the most tricky part of the hardware assembly, these are the Helicoils (also known as reduction bushes).

• 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

3. Grease Nipple (optional) Greasing (not optional)

You will need to grease the ball nut, the ball nut will likely come supplied with a light layer of machine oil, but not enough grease for ongoing operation. So two methods exist, either using a grease nipple and grease gun, or finding a spray grease (refer to forums) for this.

• 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

4.Ball Screw

Do not remove the ball nut from the ball screw at any point, be very careful if you’re close to the end of the screw, it’s easy to go a little too far and end up with ball bearings on the floor…

• 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

5. Aluminium profile mounts

• bolt the fixed bearing to its 3d-printed mount
• These bolts may be quite tight depending on printer calibration. If they are use some grease to help them along.

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

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

6. 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

7. 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

9. Actuator assembly done

Another video from Joshua showing alternative method of installing Helicoils: