New Article - Scratch Building Astartes Servo-Arms

[Lysimachus]

Hello all,

 

I recently posted on my blog a couple of pics of a scratch built servo-arm I had put together, and a couple of people expressed interest in a tutorial for it.

 

In all honesty, I can't really take credit for the design - there are quite a few similar tutorials around that I worked from; ‘standing on the shoulder of giants’, etc. But if it helps anyone, I'm happy to go through the process (hopefully it all makes some sort of sense!)

 

Ingredients:

 

3x3mm square tube
3mm dia round tube
2mm dia round tube
1.5mm dia round rod (solid)
1mm dia round rod (solid)
Poly Cement
Sharp Knife
Rounded Needle File

 

It's a little bit difficult to be precise about the measurements of the round tubes and rods (as I no longer have the packaging I bought them in) but essentially the dia of the thicker and thinner rods should match the internal dia of the thicker and thinner tubes so that they slide smoothly in and out.

Building The Main Arm Sections:

 

Cut 3 x 3x3mm square tube x 11mm length.

 

After you have these cut to length, use a needle file to add a curved indent into either end of each section, as shown:

 

 

 

Once you have these, carefully cut 12 pieces from the 1mm round solid rod. You want the length of these to be 1mm (or even less if your eyesight is up to it! ) so that they are quite flat discs.

 

These will form your rivets on the arm sections. Glue two of them to either side of each arm section approximately 1/3 and 2/3s of the way along the beam, as so:

 

 

 

What I found helpful is once they are stuck on and dried, put a small blob of poly cement on top of each rivet. The sharp edges will deform slightly, leaving a much more rounded rivet shape. (You can do this more than once if necessary until you get the more rounded shape that you're looking for)

 

Building The Joints:

 

Cut:

4 x 3mm dia round tube x 4mm length

3 x 1.5mm dia round solid rod x 5mm length

1 x 1.5mm dia round solid rod x 10mm length

 

 

Glue the rods into the tubes so that there is an equal amount of rod sticking out on either side.

 

The last (slightly longer) rod is for the bottom joint. Glue that one so that it matches the others on one side, and has a longer piece of rod sticking out on the other side. This will be your way to attach the servo-arm to your backpack - any Primaris pack should do, with one of the spherical exhaust pieces cut off and a hole drilled in the centre of where it was removed. The excess length of the bottom rod will slide into that hole.

 

 

(If the joints look a bit uneven or stick out too much, it's easy to just smooth them off a little with a file)

Assembly:

 

Start with the bottom joint and glue to the curved recess in the first arm section. Glue the next joint to the opposite curved recess, and so on. This gives you the basic arm shape, and you can choose whatever angle you wish for each arm to connect to the next.

 

Piston:

 

This is the first step of adding details to the arm. First, cut a short 2mm length (shorter than the 3mm width of the main arm sections) of the 1.5mm solid rod. Then cut it in half lengthways, so that you have 2 semi-circular sections. These are glued to the bottom and second arm sections to create the ‘wheels’ that the piston attaches to.

 

Then take a length (approx 7mm) of the 2mm dia round tube, and a similar length of the 1mm solid rod. The rod should slide in and out of the tube. That's your piston.

 

Cut a small notch out of the bottom end of the 2mm tube. This will allow you to glue the outer piston end against the curve of the lower ‘wheel’
Glue the top of the inner piston against the upper ‘wheel’. It should look something like this:

 

 

 

Obviously, the more extended you have positioned the arm sections, the further the piston will have pushed out (you can see in the pic above, this arm is at almost maximum extension).

 

Greebling and Tools:

 

The rest of the build just uses whatever you've got available in your bitz box; wires, power couplings, tech-y looking gubbins, etc, etc. Plastic cabling (pinched from spare bits from vehicles or weapon sprues?) is especially useful as you can glue these bits to actually strengthen the overall structure of the build.

 

That's about it.

 

Except of course for the whole point of wearing a servo-arm - carrying heavy tools!

 

I built my first arm with a grabber claw created from the leftover fingers of a Contemptor Dreadnought (you can see an example of adding the greebling bits here too)

 

 

 

I've seen other tool ideas too:

- a drill made from a small screw mounted in a length of round tube.

- a jackhammer chisel bit, cut from a piece of flat plasticard, again mounted into a tube attached to the end of the arm.

 

- some sort of magnetic claw or a laser cutter - I'm thinking that bits from the more esoteric HH guns (like conversion beamers, etc?) might work here?

 

- Bulkhead Shears - I've not quite figured these out, but I'm going to think about it!

 

Once you've got the arm built, the options for tools are endless! I may come back and edit this tutorial once I've had a bit more of a play with ideas for tools, and show off what I've found, but this should be enough to show what I've done to make the arm itself.

 

Anyway, thanks for reading, and I hope you have fun making your own servo-arms!

 

 

 

 

 

 

 

 

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