INTRO

In the previous page (#7) the space frame was completed. This page shows the attachment of the front legs, the claws, the motor-gearboxes that drive them and the associated other components.

(It is obvious where these are really but here are some arrows anyway). These items are located approximately where the arrows are indicating below.

When completed it will look like this:

PARTS

List of components presented in this page:

• Legs (41) (x2)
• Motor clamps (42) (x2)
• Claw spindles (43) (x2)
• Claw retainer (44) (x2)
• Claw washer (45) (x2)
• Claw (46) (x2)
• Motor-gearbox (200:1) [x2]
• Red electrical wire: 800mm
• Black electrical wire: 800mm
• black cable tidies (x8)
• M4 socket screws, 35mm (x2)
• M4 countersunk socket screws, 10mm (x2)
• M3 countersunk socket screws, 35mm (x4)
• M3 socket screws, 10mm (x2)
• M4 lock nuts (x4)
• M3 nuts (6)
• M3 washers (4)

The new parts are shown below, coloured blue.

Exploded views below….

ASSEMBLY

The parts are shown below as they are assembled:

The starting point is to attach the legs

M4 x 22mm socket screws and nuts were included in the assembly on P7 and these are used to secure the legs.

The leg and the top shoulder lugs sandwich lugs from two other parts as shown below (yellow arrows):

The sandwiched lugs are from the left and right Y-frames (15 & 16) and the left and right shoulder links (35 & 38).

All four legs are the same so attach one on the other side in the same way.

It is now necessary to prepare the motor-gearboxes (solder wires on etc) and to attach the motor spindle parts.

Motor preparation was shown on Page 1 and can be found about 3/4 of the way down that page.

As these motors are further forward on the device, allow about 400mm wire length.

Before attaching the motors to the legs it is necessary to build up the spindle sub-assembles. The components are shown below.

The orange arrows indicate the parts which are, from left to right: the claw spindle (43), M4 locknut and the claw retainer (44).

The locknut should be inserted into the end of the spindle as shown with the nylon locking part going in first. The spindle has a hexagonal recess for this (as shown further above).

Now glue the retainer (#44) into the end of the spindle with superglue. This traps the M4 locknut inside.

The M4 x 10mm countersunk machine screw can now be used to hold the claw in place.

This assembly procedure is the same for the left and right legs and claws.

The above sub-assembly can now be inserted through the hole in the leg.

The motor gearbox spindle is approximately rectangular in shape and slots into the rectangular recess on the back of the claw spindle flange.

The motor-gearbox is held in place using the motor clamp (42).

This is held in place by two M3 x 35mm countersunk screws (blue arrow below) and M3 nuts.

There are lugs on the reverse of the clamp and these are connected to the outer lugs on the breast bone (37) as shown below. This is done with an M3 x 10mm socket screw and corresponding nut and washers.

Nb do not over-tighten.

The next step is to add the claw.

Insert the M4 x 35mm socket screw and M4 locknut to create the claw clutch mechanism.

Now using the claw washer and the M4 x 10mm countersunk socket screw, the claw sub-assembly can be attached to the claw spindle. The countersunk screw engages with the M4 locknut that was trapped inside the spindle (explained above).

As you can see, the M4 locknut is housed in the hexagonal recess and so, as the M4 socket screw is tightened so the claw it will grip the spindle.

It is recommended to adjust it so that some slippage is possible i.e., under higher loadings. This can be done by trial and error.

The slip clutch design protects the motor and gearbox but also it allows the whole device to slip if it encounters an obstacle. So, if one claw can’t rotate it will slip on the spindle and the onus will be on the other three claws to get the device around the obstacle. So with three legs working and one not, the whole item will tend to slide around in the direction of the side where two claws are still working together. This can cause the stopped leg to become freed of it’s obstacle and the whole effect can be quite life-like. If there is no slippage on the axle then sooner or later the motor will become damaged and will start to squeal and will need to be replaced.

The leg assembly is now complete: simply repeat the above steps for the other front leg.

The wires from the motors should be attached to the space frame as shown below with cable ties.

It should now look like this:

The next page shows the assembly of the rear legs.