Lorica is Latin for "armor;" segmentata is a modern term applied to the classic Roman iron cuirass of bands or hoops, introduced by the early 1st Century CE. Its origins are unknown.
The following patterns and guidelines are for a Corbridge type A cuirass, followed by options for the type B lorica. (Be aware of the subtle differences in detail.) Complete drawings are found in Excavations at Roman Corbridge: The Hoard (ISBN 1850741913). The terminology used will be from the Corbridge report, as shown below. These are purely convenient modern terms and should not be tossed out to the public as if the Romans used the same wording.
Construction of a full-scale cardboard mock-up (at least of the collar plates and one pair of girdle plates) is highly recommended to assure a good fit.
The basic material is 18-guage mild steel, not galvanized or stainless. Thinner steel (20-ga) may be used for the collar sections and upper shoulder guards, both for ease of cutting and to keep the weight to a realistic 14-15 pounds. The outside should be scoured to a satin finish (with med-fine sandpaper) before any fittings are attached, and oiled or waxed to prevent rust. The inside should be painted black with a rust-inhibiting paint. (Originally the inside would have been black from the forge.)
There are rolled or folded edges on the collar plates where they lie against the neck, on the upper girdle plates under the arms, and around the entire bottom edge of the bottom girdle plate. The outer edge of the outermost lesser shoulder guard plate can be rolled under or flanged upwards. Rolling edges is not very difficult; simply bend over the edge (approximately 1/4" width) with a large pair of pliers, little by little, working back and forth along the piece. When the bend approaches 90 degrees, pound it over the rest of the way with a hammer.
Fittings are (and were) made of brass. Metal snips or shears, small chisels, or a dremel tool can all be used for cutting, and small files as needed for finishing the edges.
Folding the hinges can be made easier by annealing the brass; heat it red hot in a gas flame and allow to cool. This will discolor the metal, but a 50/50 mixture of vinegar and water with a little salt will brighten it in minutes ("pickling"). A quick application of Nevr-Dull or other metal polish will restore a mirror polish. Brass that is not annealed should be scoured to remove any modern coating. All brass fittings may be tinned or silvered.
Be careful when using steel tools on brass, as they can leave permanent marks in the metal.
Hinges are made from 0.032" thick brass; 3 sheets of 4"x10" hobby brass will suffice. For 8 hinges cut out 16 halves as shown; a finished hinge is a double layer. Fold each piece in half with a 1/8" rod at the fold, and strike with a square edge or clamp in a vice to form the "tube".
Cut away alternating sections of the tubes, or "saw" away with a coarse file, to mate 2 halves together. Remember that the top half will overhang the edge of its plate, and the lower will sit flat about 1/4" back from the edge of its plate. File well to make the edges even.
Use 1/8" brass rod for the hinge pins, peening or flattening the ends to keep them from slipping out.
Punch or drill the rivet holes on the hinges, then assign each hinge to a specific place on the armor and mark it accordingly. Trace the holes of each hinge onto its specific plate, and drill or punch carefully. Remember, the hinges are all a little different, and their hole patterns might not be interchangeable.
The strap and buckle hinges are made in a similar fashion. The buckles can be made from strips of sheet or from rod, the ends flattened and drilled for a 1/16" pin. The tongues are also made from strip. Make 4 hinged strap and buckle sets, plus 4 buckles without hinges for the inside back.
Lacing Loops are cut from 1 sheet of 0.032" brass. Cut 24 as shown (or use one of the alternative types) and curl the tongue backwards into a circle. The loops are riveted at the bottom edges if the girdle plates. On the left side plates, the loops overhang the ends slightly, front and back; on the right they are set back about 3/4" from each end. There are no lacing loops on the bottom 2 pairs of girdle plates.
Bosses are stamped out of thin brass (0.010").
Three types of brass rivets are used; flat-headed, small domed, and large domed. The flat-headed type is used for riveting the girdle plates and lesser shoulder guards to their internal leather straps, and about 130 are needed. They are put in place from the inside, first through the leather and then the metal, and hammered flat outside the steel; no washers are used.
About 160 small domed rivets (1/8" diameter shank) are needed for the hinges and loops. 24 large ones (3/16" shank) are used for attaching the upper shoulder guards and back plates to their leathers; some of these also secure the stamped decorative bosses. (Optionally, small domed rivets may be used in place of the larger ones.)
Since the large domed rivets must be peened (flattened) over leather, about 24 washers are needed. Draw a grid of 1/2" squares on 0.015"-0.032" brass, put a hole through each square, and cut along the lines.
Drill all holes no larger than necessary for the rivets to go through. Remove burrs with a file or small grinder. Put each rivet in place and cut off the excess shaft very close to the surface of the metal or washer; about 1/16", plus a "peak" left by the cutters.
Flat-head rivets being peened are simply rested on a convenient hard surface, but for dome-heads, a riveting tool is essential. This is just a chunk of metal with a couple shallow holes drilled into it, in which the rivet heads can rest so that they stay domed.
The best leather to use is five ounce tooling leather with a good coat of neatsfoot or similar oil. Anything thicker will reduce the flexibility of your lorica. A waxed leather may work, but might be stretchy-- beware.
The six girdle plate leathers are approximately 1½" wide by 12" long. The pairs of holes are 1 5/8" to 1 7/8" apart (depending on your height), except that the uppermost pair on the middle leather for each side is a little lower (because of the rolled edge at the middle of the top plate).
Each trio of backplates is riveted to a pair of leather strips 7-8" long by 3/4" wide. These extend below the bottom back plate to reach the buckles inside the top girdle plate.
Shown below are the leathers for the shoulder units, 1/2 actual size. Hole placements for the upper shoulder guards and collar pieces may vary slightly.
The upper shoulder guard plates, mid-collar plates, and the tops of the breastplates must be curved to fit the shoulders before they are connected by their hinges. Assemble the collar units with the backplates, and put all the strap and buckle sets in place. The lesser shoulder guards are curved to fit, then riveted to their leathers. They are next attached to the collar units, and the upper shoulder guards are riveted on last.
The lacing loops and rear buckles are best riveted on before the girdle plates are curved. The girdle plates are more U-shaped than semicircular; shape the bottom plate first and make each plate fit the one below it. Then check the fit of the top plates. They must not stick out and press against the insides of your upper arms (this can cause discomfort and numbness!). If the girdle plates are slightly too long it is better to reshape them so that any looseness of fit is at front and back rather than at the sides. Finally, assemble the girdle sections again, working from the bottom upwards.
Type "B" Lorica
Separate patterns for the type B lorica are included, but type A patterns can be adapted and type B fittings applied, if you prefer.
Hooks and eyes connect collar unit to girdle plates. Cut six hooks out of heavy brass (18-ga), matching the lacing loops but with tongues 1/2" longer. Also cut 6 eyes; the two for the front must be thick, but the four at the back can be thinner since the holes go through the back plate. (On the type C cuirass the back eyes hung below the plate like those at the front, and all were iron, not brass.) Place hooks and eyes however they work; symmetry is not necessary.
Hinges are a less refined shape; see patterns.
There are only seven pairs of girdle plates, so only 20 lacing loops are needed. Loops are not mounted flush with the bottom edges of the girdle plates as shown, but 3/8" up (see patterns).
Backplate leathers can be 1/2" strips, or single 4-inch square.
Upper shoulder guard plate is pentagonal, either point towards neck, simply because the front and rear plates are tapered.