14. The ‘umbilical’ cable and wiring

INTRO

Tip: please read through this page completely before you begin the steps.

The assembly of the controller was shown in the previous page (>>> Page 13). This page shows the steps needed to make the ‘umbilical cord’ and for finalising the wiring. This is the last stage of the project.

When completed it will look like this:

Below is an overview of what is required and then the steps needed.

PARTS

List of components presented in this page:

electrical connector jacks, male (x4)
electrical connector jacks, female (x4)
red wire (12m)
black wire (12m)
black heat shrink tubing (3mm dia’)
black heat shrink tubing (6mm dia’)
black cable ties (x13)
green cable ties (x4)
orange cable ties (x4)
yellow cable ties (x4)
spiral cable tidy (600mm)

ASSEMBLY

The tail rod is held in place by friction (see the final part of : >> Page 10 for more details) and is removable. In this way, the user can totally separate the controller and cable from the main device for storage and safety purposes.

For that to be possible, the wires need to disconnect and so we have used push-fit cable jacks.

There are four male-female jack connections:

power (from the battery to the control console)
left legs
right legs
lunging and biting (head / neck / jaws)

In addition, the battery also has a female jack to which the charger is attached.

The male and female of each jack pair (not including the battery connectors) should be colour-coded using cable ties, as shown below.

The output from the battery is a male jack so we followed that convention. So on the ‘rod’ side (shown above) the female jack joins to the male jack from the battery and the 3 male jacks carry the power from the hand-held control console (left legs, right legs, neck/jaws).

So that is a quick overview and the following are the steps needed to achieve it.

On page 10, the main device has three pairs of wires hanging out of the tail base plus the male battery output jack and the female battery charging jack.

Firstly, insert the tail rod into the tail middle section.

The first item to add is a female jack to join the male battery jack.

This is shown below.

As can be seen, the wires of the female jack on the right can be temporarily held by a piece of spiral cable tidy and then secured with a black cable tie (this may need to be removed later when other wires are in place).

The wires from the battery on the left in the image above can be secured to the tail base with a green cable tie.

(NB, green chosen because that is the colour of the tail base. Any colour is fine. A selection is supplied in the kit).

Next, isolate the two wires that come from the left hand leg motors.

To these solder a female jack as shown below (trim the wires first to c. 50mm long):

Once soldered each wire should be covered in 40mm of black or red heat-shrink tubing (Tip: don’t forget to thread it in place but out of the way before soldering!).

Lastly, colour-code it with a green cable tie.

Now tidy the wires and fix to one of the bars of the tail base with another green cable tie. Next attach the male jack and colour code this also:

Next secure the wires from the male jack to the tail rod with a black cable tie:

So, if disconnected, it is easy to see how to re-connect them:

Repeat the above process for the other pairs of wires (right legs circuit and biting circuit). These can be colour coded with orange (mouth / jaws etc) and yellow wire (right legs).

It is now necessary to cut four lengths of red wire x3m long and four lengths of black wire x3m long.

Solder these to the four pairs of wires coming from the back of the four jacks (one female, 3 male) that are now attached to the tail rod. Then isolate each individual join with a 40mm length of black 3mm dia’ heat shrink tubing.

Once that has been done, bind the wires into a single ‘loom’ using 6mm diameter heat-shrink tubing.

So, cut 30 lengths 75mm long and attach them every 150mm along the loom. That is, the wire loom will have heat shrink tubing then a space and then another after 75mm along it’s whole length. This keeps the loom tidy but allows the cable to flex. Tip: thread the last 4 or 5 lengths (that is, at the controller end) of heat-shrink tubing but do not shrink into place until the other end of the loom has been wired up.

Bind the loom to the tail rod with c. 4 black cable ties to about half way along it’s length. Finally finish it off with a length of spiral cable tidy. Use another 4 cable ties to bind the spiral to the rod. It should now look like this:

So, that completes the wiring of the main device. The four connector jacks can easily be disconnected and are colour coded for ease of re-attachment and the tail rod can easily be be taken out of the tail middle section.

So, by now there should be approx. 3m of loom attached to the tail rod. The next step is to connect the other end of the loom to the controller. This is the final stage of the project.

This stage is very simple in theory but can be a little tricky just because there are so many wires to deal with.

The controller should now have 4 pairs of wires extending out of the end of the handle. These are:

the input power wires
the left legs skid-steer wires
the right legs skid-steer wires
the head / neck / jaws lunging and biting wires

So the first step is to identify these (either via labelling done previously or by trial and error). Once identified use coloured cable ties to correspond with those used above.

These were:

no colour code (input power from the battery)
green (left legs)
yellow (right legs)
orange (jaws)

Now do the same with the wires in the loom.

So the next stage is to join them all together temporarily taking care not to create any short-circuits. Test each one to check that the polarities are correct*. That is it is unlikely that all the red wires will join with red wires and the same goes for the black. Work these out by trial and error.

[* correct polarities: i.e., that the legs rotate in the right direction and that the top crank pairs that move the head and neck etc should rotate anticlockwise if viewed from the left side, clockwise if viewed from the right side].

The next stage is to cut 8 lengths of 40mm long, 3mm diameter heat shrink tubing (black).

Now carefully disconnect each of the temporarily coupled wires one at a time, slide on the heat-shrink tubing, solder the pair together and then insulate the join in the usual way with the heat-shrink tubing.

Once complete it should look like this, roughly speaking:

NB, remember that the non-colour-coded pair will be from the battery.

Test the system again.

Now, inevitably, some pairs of wires are going to be slightly longer than others. (It would be very difficult to ensure otherwise).

To ensure against future damage, identify the shortest pair of joined wires. Then fold this pair back on itself into an ‘S’ shape and bind the middle with a single cable tie. By doing this, if the umbilical gets yanked during usage, the folded wire can extend to absorb the shock and hopefully no damage will occur.

Tip: at every stage test the system again.

Gather together the wires into a bundle and wrap with insulation tape.

The final step is to use 400mm of black spiral cable tidy. Wrap this around the cable and tuck the end into the hole at the end of the controller.

There is a slot on the reverse of the handle and two holes at the front. This is to fix the spiral on the inside of the handle using a black cable tidy, as shown below.