Wednesday, February 18, 2015

Building the DSLR sized CableCam - Part2 - The two Arms

This Blog post is one of an entire series
Motivation and Design

Building the two arms

Our goal here is to build the two arms of the cablecam, as shown here.


The four main parts are all identical, hence it does not matter which you start with. Just make sure you build two symmetrical arms with the wheels and the longer distance nut on the same side.
The two cover plates on the other hand are slightly different, the one with the sensor wheel has a few more holes.

You start with the 5pieces (for each arm) 30mm distance nuts where you put the 16mm stud screws into.


This goes into one side of the arm. The 30mm distance nut is the side where the wheels will be.

 The other side the 25mm distance nut is mounted.

Then you take the other arm plate and add the other 7 distance nuts of 25mm length, mounted using the M3x10mm screws.

These two plates can now put together. On the one side using 5 M3x10 hex screws.

On the wheel-side using 5 M3x10 hex screws for arm1 and just three for arm2. In both arms the two distance nuts below the 5 30mm nuts are left as is, there the safety screw will be put into.
The second arm has two screws less for the battery holder - see next picture.

There you put the two 60mm threaded rods into and secure them using a locking varnish. Obviously, in case you intend to mount the battery somehow differently, you can ignore these steps and rather use screws.

Finally the cover plates can be mounted on both arms. Use the cover plate with less holes on the arm with the battery holder, the other will get the distance sensor then.

Finally you add two M3x40 screws as shown here on both arms. Do not tighten them, they should just ensure that the cablecam will never fall off the rope, no matter what happens. Whenever the cablecam will be put on the rope, you will remove them and put them back after for safety.

Next step is to prepare for the skate wheels by mounting the M6x25 distance nut with a M6x8 screw on each arm. There are four positions you can mount them to achieve more or less friction on the drive wheel. A steeper hill needs more force, extreme high speed less force. But you will find out and can change later. Best to start is the 2nd from above by my experience.

The skate wheels themselves consist of the following parts:

  • 2 ball bearings 608
  • 1 spacer between the two ball bearings and short enough for the spacers
  • 2 spacers
  • 1 M6x30 screw


Note that one skate wheel has 22 d3x8mm magnets with alternating poles put into the wheel at a 60mm diameter circle. There the distance measurement PCB is added. This is all optional and can be done later as well.

First step is to push one ball bearing into the wheel and add the spacer.

Then the second ball bearing. The idea of this is to reduce the bolt diameter from the 8mm the ball bearing has to 6mm and to ensure the ball bearing is has no axial force applied by the screw, else the wheel will not spin freely.

On both sides of the wheel the spacer is added as well to ensure the wheel itself has no contact with the frame, only the axis.

And finally all is mounted into the arm using the M6x30 screw.



The final step is to complete the battery holder, if applicable. Previously we have attached the 60mm threaded rod to one of the arms. The battery holder parts consist of 4 pieces, two of them have a M3 thread. There goes the 50mm threaded rod, again secured by a locking varnish.

The two parts are then put onto the arm and secured by one M3x5mm distance nut each.

Then you add the two other battery holder parts and the M3 knurled thumb screw, which will be used to lock the battery in place.





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