Rivetback H-6 V4

15 files, printed 61 times, held together by 12 printed pins.

A six-legged machine that stands 9.5 × 5.8 × 3.1 in over its feet and weighs 4.7 oz once it is together. Nothing on it turns. The legs key into the chassis at 6 fixed stations and stay in that splayed stance, which is the point — it is a thing to build and then look at.

What it does do is come apart. Every structural joint is a square tenon in a square socket with a pin driven across it, and the pins are printed too. There is no glue in the kit and no hardware to buy.

The assembled Rivetback H-6 V4 standing on a tiled workshop floor, seen from the front and slightly above: a wide, low charcoal frame carrying a stack of faceted yellow armour plates, six splayed legs with yellow shin plates, pale curved conduits at the knees and grey pin heads at every joint.
Printed in PLA. The layered back is 3 yellow base plates with 3 more shells keyed 7.2 mm above them.

61 pieces, in the order they go on

Everything on the plate

The kit is 15 files and 61 pieces come off the printer: the leg parts go on the plate 6 times over, and the lock pin 12. The chassis is the only piece that never moves after that.

Base armour

3 yellow plates drop onto the chassis pegs — 4.0 mm posts into 4.4 mm sockets, 0.2 mm of clearance a side, so they seat under thumb pressure and stay put.

Dorsal shells

3 more shells key into the plates 7.2 mm higher on square 8 mm keys. 6 layers of armour over one charcoal frame, with the dark gaps between them left open.

One leg of the 6

9 pieces to a leg: a hip yoke, two beams, two shin plates, a conduit, a foot, and the 2 pins that lock it. Beam to beam is an 8 × 8 mm tenon in an 8.5 × 8.5 mm socket.

The pins

A printed 3.2 mm shaft crosses hip and knee through a 3.6 mm bore, 0.2 mm a side. 2 per leg, 12 in the machine, and they are the only fasteners in it.

Standing

The other 5 legs are that same 9-piece design at their own stations. 61 pieces, 9.5 × 5.8 × 3.1 in over the feet, 4.7 oz on the shelf.

How it holds

A beam ends in a tenon 8 × 8 mm across. The piece it goes into opens a socket 8.5 × 8.5 mm, which is 0.25 mm of air on every face — less than one bead off a 0.4 mm nozzle, so it is a firm push rather than a fight or a rattle.

Then the pin. A printed shaft 3.2 mm across goes through a 3.6 mm bore drilled straight through both pieces, and the joint stops being a push fit. The head stands proud with a hex recess sunk into it; there are 12 of them down the flanks, and they are most of what you see of the machine's hardware.

Pull the pins back out and the legs come off in your hands. That is the difference between this and a model you glue: it is a kit twice.

Section through a keyed beam joint A tenon on one beam sits inside a slightly larger socket on the next, and a printed pin with a hex-recessed head passes down through both. hex recess in the head 3.2 mm pin 3.6 mm bore 8 × 8 mm tenon socket 8.5 × 8.5 mm 0.25 mm a side
Close view of one leg: the yellow thigh plate standing off a charcoal beam, a pale bone-coloured crescent conduit arcing across the knee, and the flat grey head of a lock pin sitting proud of the joint beside it.
The knee, printed. The pale crescent is the conduit; the grey disc beside it is the head of the knee pin, sitting proud of the beam.

15 files, 61 pieces

The body is 7 pieces and every one of them is its own file. The legs are the other 54, and they come off only 8 more: 7 shapes printed 6 times over, plus the lock pin printed 12. That is why a kit this size still only asks you to slice 15 things.

Largest piece on the plate is the chassis at 78 × 86 × 16 mm, so a 180 × 180 × 180 mm bed prints everything without splitting anything.

Every file, and how many of each you print.
Chassis corecharcoal1
Carapace, foreyellow1
Carapace, centreyellow1
Carapace, aftyellow1
Dorsal shell, foreyellow1
Dorsal shell, centreyellow1
Dorsal shell, aftyellow1
Hip yokecharcoal6
Upper leg beamcharcoal6
Upper leg plateyellow6
Lower leg beamcharcoal6
Lower leg plateyellow6
Knee conduitbone6
Footcharcoal6
Lock pinsteel12
15 files61
The machine from directly above: three yellow armour layers running down the centre, six identical legs radiating out to blunt black feet, a pale conduit at each knee and two grey pin heads on every leg.
From above, the repetition is the whole design: one leg, at 6 fixed stations, the outer pair swung 32° forward and aft of the middle.

What you are printing

Figures below are off the built assembly and the slicer, not off the brief. Sizes you would measure are in inches; sizes you would set on a printer are in millimetres.

  • Standing size9.5 × 5.8 × 3.1 in
  • Assembled weight4.7 oz
  • Clear air under the chassis1.2 in
  • Pieces in the machine61
  • Files to print15
  • Print time, whole kit14.7 h
  • MaterialPLA
  • Largest piece78 × 86 × 16 mm
  • Build plate needed180 × 180 × 180 mm
  • Nozzle0.4 mm
  • Thinnest structural wall0.8 mm
  • Tenon and socket8 × 8 mm, 0.25 mm a side
  • Lock pin and bore3.2 mm in 3.6 mm
  • Carapace peg and socket4.0 mm in 4.4 mm

12 pins in, and it stands there.