On Making the Bronze/Brass Edging on the Cheek plates and Helmet Fan

An example in the art of modern armouring

You will need an oxy-acetylene torch and a bucket of water for annealing the brass or bronze strip, an anvil, a polished light tack hammer, some metal working and brazing experience, and lots of patience. You should add the bronze edging after the steel parts have had their upset lines, fluting and other shaping completed and are at their final, overall shape.

First off, this is going to require experience with armour to make it easy to do. That is not to say you can NOT do it, but such experience with brazing and metal work will make it much easier. Even if you have no experience, you will learn how to do this with practice. If you refuse to attempt it, you learn nothing. So, read on. Here are the steps to adding the brass/bronze edging to a cheek plate. Substitute the word brass for bronze below as applicable.

1) Cut a strip of 20 gauge thick bronze 1/2" wide and a bit longer than the length of the edge you want wrap it along.

2) Heat 4" of the strip with the torch with the flame having a large blue cone, not a small and bright one such as you would used for steel welding. Heat it until cherry red and dip it quickly into cold water. Do not heat it to orange red or you risk melting right through the strip or causing shrink cracking as you plunge it into the cold water. Then, heat the next 4" section and quench it again. Repeat until the entire strip has been annealed. You now have a buttery soft strip of bronze. A note on the behavior of metals you want to anneal: Quenching nonferrous alloy like brass or bronze allows no time for the atoms to line up and make a coarse, crystal structure that is inflexible. This leaves trillions of small grains of crystal structures aligned in random directions. The metal is thus very soft since it is made up of trillions of smaller crystal structures that slide more easily over one another instead of larger crystal grains that do not . Annealing steel is the OPPOSITE. You quench it to lock the carbon atoms in locations jammed between rows of iron atoms (interstitial carbon atoms), making the layers of iron difficult to slide over one another and thus making the steel harder. It also has to do with changing the predominant phase structure of the metal to create more amounts of the harder phase, and less amounts of the a softer phase by percentage. Many other factors go into the heat treatment of carbon steels. Consult a basic metallurgy book for details.

3) Using a vice and a hammer, or rolling it through the "U" shaped channel dies of a rolling jenny tool, begin to fold the strip into a "V" shaped strip along the entire length.

4) OPTIONAL STEP (for better grip of the bronze to the steel edge) This is done on real roman helmets to hold the strip better in the edge. Take the cheek plate and cut very tiny notches along the edge that are NOT nearly as wide as the bronze strip that will wrap around the edge.

5) Take the strip and lay the edge of the cheek plate at a starting and fold the "V" shaped strip end tight to the steel using the hammer and anvil for the first 1-1/2" of strip length. You do this by laying the strip on the anvil, inserting the edge of the cheek plate, holding the steel deep into the "V" of bronze, and tapping the "V" closed over the steel edge.

6) Now that the first inch or two of strip is firmly clamped on the steel edge, place a vise-grip pliers on the strip about 1 1/5" away from the starting end of the strip to hold it on the steel.

7) Now braze a spot on the INNER side of the cheek plate to attach the end of the strip to the steel plate. Alternatively you may use a propane torch to solder the strip to the plate at this point. The Romans would have used the solder method. The little notches in step 4 above allow for better bonding of the solder between the steel and the bronze, and a propane torch is cooler that a oxy-acetylene torch so the heat amount is easier to control. If you opt to braze the strip at this spot, make sure you use flux to achieve a good bond to the steel and add a tiny bit of bronze to the joint with a bronze rod. When finished, remove the vise-grip pliers. You want the tacks on the inside surface of the cheek plates because they will not show after you line the inner surface of the cheek plates with leather.

8) Now bend the strip around the curves of the cheek plate and fit it to the edge with firm presses with your fingers for a length of about 4" along the edge, no more. Do not be concerned with the unfolding of the strip and the puckers that occur, but try to keep the strip from twisting and work it with your fingers to get the edge of the steel firmly into the root of the "V". Using thicker 20 gauge bronze or brass instead of that thin 30 gauge brass tube that is commercially available will help make it easier to prevent folds and puckers in the sharp bends around round corners. It's like moving hard clay instead of trying to bend paper in to a ball. The puckers will collapse into themselves easier with thicker metal, because the metal surrounding the area you are hammering to smash down is stiffer and won't form puckers. From here you will be folding the "V" channel strip close with a hammer and anvil in short, 3"-4" long segments. If you bend the strip around a sharper curve of the steel plate farther down the edge than you are currently working, the strip will not spring loose as easily and the work will be easier to handle.

9) For the first segment, go about 4" along from where you last tacked the strip, and hammer a 1-1/2" long length of strip over the steel edge to secure it. Bite down on this area of the strip with the vise-grips to hold it tight to the edge. Now start from the last braze/solder tack location and hammer the "V" of the strip flat so it is wrapped around the steel edge right up to the location of the vise-grip. If the strip pulls away from the edge, leaving a gap at the root, take the vise grips off, press or hammer the strip to squeeze of the gap, and re-clamp the strip with the vise grips and continue flattening the "V". You may have to reform the strip to tightly fit the curves of the steel check plate, and re-clamp the strip with the vise-grips to pull out any gaps and insure that the steel is inserted into the bronze strip all the way to the root of the fold. If you over-hammer and area and the bronze has become hard, you should make it soft again and finish forming it by annealing it as in step 2. Don't be concerned about the blue or gray oxidizing of the steel plate as it gets hot because you will restore the steel finish later by sanding and polishing. Annealing the bronze when it becomes difficult to work is important so you make your forming easier and do not risk cracking the delicate strip with hammer blows. You have to use judgment as to when to stop hammering the fold and re-anneal the strip. sharp curves may require you to re-anneal the strip at these locations in order for the bronze to be soft again and allow you to finish forming the bends without puckers in the bronze. You will be surprised how well the soft bronze moves and how puckers collapse under the hammer.

10) Braze or solder another spot on the inner side of the cheek plate near the vise grips (step 7) once all the gaps have been worked out and the bronze is hammer-folded up to this point along the edge. Light taps around sharp curves will fold the soft bronze into itself without puckers. Be careful while brazing. If you screw this up by overheating and melting off the strip, you had better be a darn GOOD and experienced brazer in order to re-attach it to the steel edge, and fill in the gap with brazing rod filler metal, and grinding and sanding the excess lumps of bronze that remain after you are finished completing this bronze edging job. You notice the lumpy area of the bronze edge at the bottom of the right cheekplate in the picture below, That's where I melted the strip off while attempting to braze-tack it on the back side, and the metal got too hot. So, beware.

11) Continue fitting, folding, tacking, and occasionally re-softening the strip as your work around the edge of the cheek plate until you come to the end. At the end, make the final braze or solder tack to hold the end to the steel edge and then cut the remaining strip off with a hacksaw, holding the cheek plate gently in a bench vise. For a cheek plate the strip will be cut to it ends about 3/8" from the top edge of the cheek plate, leaving a short tab of metal un-edged. This tab will become rolled to make the hinge, and you don't want to have to roll the bronze edging along with the steel to form the hinge loop! The bronze edge stops short of the hinge fold. Adding a "riveted end holding strips" at each end of the bronze strip to prevent the ends from popping off the edge of the steel was done on some, but not all helmets. Using such holding strips means you may not have to use solder at the ends. You may still need to solder-tack some areas in the center of the strip as you work it around the periphery of the steel plate. When brazing, the lining on the inside of my cheek plates hides the tacks well, and if you are skilled you can sand away excess tack brass that offends the eye. You will have to sand away excess solder in any event if you use solder, especially if the liquid solder runs through the joint and pools on the outer or visible side of the joint.

12) sand the oxidation off the cheek plate and polish the plate and the bronze edging with a very fine Scotchbrite deburring (polishing) wheel. Or, use whatever polishing tools you have on hand. Be careful not to sand through the bronze edging in an attempt to remove hammer marks or smooth its overall appearance. It is thin. If you can pull this off, be proud of yourself. THE FINAL RESULT:


 

 The carrying ring is found on most Gallic helmets at the rear of the fan of the helmet. Brass or bronze staples hold the ring to the fan. The helmet is slung to the front of the lorica or to the soldiers stick-pack when not worn. The rosette shown above the carrying ring marks the position where a small ring is riveted to the underside of the fan. The helmet strap is tied at its center point to this ring.