User:Stever/Projects/rondeldagger

From rLab Wiki
Rondel Dagger mounted on the wall at rLab

Over the course of 2020 I made a replica of a Rondel Dagger that's found in the Royal Armory collection. This project started as a growth from the basic bladesmithing workshops as I was expanding my skills and planning out the intermediate bladesmithing course. I'd seen images of a rondel dagger from the Royal Armory collection dating from 1371-1399 and with an octagonal guard and pommel and thought it would be an interesting project to make a replica. This project wound up using more of rLab's tools on one project than I've ever used on a single project before.

The first stage in making the replica dagger was to forge the blade, this is made from what I believe to be EN45A Steel that came from a steam train suspension spring that had broken in use. It's one of the harder metals to forge that I've encountered so far and has a very high hot-hardness. Still our forge was able to heat it enough to make it workable and over the course of 2 days it was forged into the shape of the blade blank and with a long tang to fit it into the handle. The very high silicon content of the metal which makes it so hard to work also had advantages here as it helped it to resist oxidization and prevented it from loosing too much carbon to harden later.

Once forged into the rough blade shape it was cooled and annealed to make it soft enough to work and then the large linisher was used with a zirconia belt to form the blade into the final shape of a rondel dagger, which has an unusually thick and heavy blade that tapers along it's entire length. Hand filing was used to shape the transition between the blade and the tang so it would sit snugly into a handle.

Detail of the handgrip

With the blade shape finished attention turned to the handle which is made up of identical pommel and guard sections and a hand-grip. The hand-grip was made from some (probably) teak that was around the lab which was drilled out with a 5mm bore all the way through then mounted up on the wood lathe. The grip was turned down with finger grooves spaced to my hand, then sanded with increasingly fine emery paper until it was completely smooth, it was parted off and then treated with 8 coats of danish oil, sanding between each coat to give a smooth but still gripy surface.

As the original, being an archaeological find, was a little short on detail I decided to improvise a bit on the guard an pommel piece and take inspiration from other daggers from the same period to fill in detail where the original was lacking. These 2 sections were made from a sandwich of the same teak(probably) used for the hand-grip in between 2 sections of octagonal stainless steel with 8 rivets holding each sandwich together. Stainless steel obviously wouldn't have been available to the original makers but given that these sections are in contact with the hand when held, and I don't have servants to polish them every time someone touches them, stainless seemed a sensible choice!

Machining the Stainless plates

The teak was cut on the table saw and then reduced to target thickness of 4mm using the planer (very carefully, working with material that thin on it is rather hard!). The stainless steel was cut to approximate shape using the metal cutting blade on the band-saw and then mounted up in the boxford CNC milling machine. It turns out that stainless steel is quite challenging for the boxford to work with, but given enough time and care I was able to have it produce some of the octagonal sections needed to make the guard and pommel, in fact it had to make quite a lot as it turned out the assembly of these sections was quite challenging and I messed up several attempts before getting it right. The timber was cut to approximate size and them clamped up with the octagonal steel sections and drilled through so that everything aligned perfectly. Finally everything was cleaned using the ultrasonic cleaner and then came time to rivet the whole assembly together......

I forgot how much I hated cold-riveting by hand back when I was trained, it's a horribly tedious process with many opportunities to go wrong! On the first attempt I made the mistake of attempting to put epoxy glue between the wood and metal to ensure a strong bond, it turned out this was unnecessary and wound up just making a huge mess and ruining a couple of bits of steel and wood. In fact it seems throughout this project, every time I deviated from the techniques that the original medieval smiths would have used, things started to go wrong. I guess maybe people who spent literally their entire lives learning how to do this and getting good enough to work for kings might have known what they were doing.... who'd have guessed.....

Detail of the finished guard

After another couple of tries and another couple of failures I did get a guard and pommel riveted together correctly and neatly, and then finished them on the large linisher again to leave a flat surface next to where you grip and the rivet heads exposed on the outside as a decorative detail. The edges were finished and beveled also on the linisher and the flat backs then sanded down with emery paper up to 400 grit using a granite slab as a flat surface to ensure they didn't get too uneven. The teak was then oiled with 8 coats of danish oil and wax-polished. The holes in the center of each were then gradually opened out using needle files to fit the tang of the blade in a process that took about 4 hours.

With most of the parts now made it was time for a test assembly. The first stage of the process was "burn-in" the tang of the blade by heating it up to about 400C and then pushing the handle over it until the heat burns the opening wide enough for the tang to fit snugly. This had to be done before the final hardening of the blade as otherwise the heat from this process would ruin the temper of the blade and make it impossible to sharpen properly.

All the parts now at their final sizes, it was time to harden the blade so it could take a proper edge, only problem was we didn't have a tank large enough to quench the blade in to harden it, so I got hold of some thick walled aluminium pipe and using some aluminium plate we had laying around and the MIG welder I welded up a new, much larger tank. This new tank is big enough to do swords since I plan on trying to make a Roman Gladius at some point in the future and is 700mm deep and holds about 20L of vegetable oil, we use vegetable oil for quenching blades instead of mineral oils despite the smell as they're considered a much lower health risk when heated to smoke point.

New tank fabricated it was back to the forge for the blade to be normalized and straightened (and re-normalized, and re-straightened, and re-normalized and..... you get the idea). Once the blade was stable and relieved of all internal stresses it was put through a process of grain refining which changes the structure of the metal to adjust the size of the crystal grains within it. Doing this maximizes the strength and toughness that can be achieved without lowering the final hardness too much. In the final forging process the blade was then heated to 900C, held at that temperature for a couple of minutes, and then plunged into the oil. After hardening the blade was cleaned up and the scale removed using the buffing wheel before hardness testing. Testing it with the ultrasonic hardness tester revealed a final surface hardness of around 53HRC which is a good hardness for this type of blade being hard enough to take a good edge but still tough enough to withstand hard use.

The blade was then re-cleaned and final re-shaping done on the large linisher using specialist ceramic belts before being moved to the small linisher to put the bevels on the cutting edges. With an approximate edge formed it was over the polishing wheels to move through the coarse, medium and fine wheels to put a mirror shine onto the blade, before it was first sharpened with the water stone and then with the sharpening stones set. It has to be polished before sharpening as action of the polishing wheels will round-over and ruin a sharp edge. The stainless steel sections were then buffed using the coarse, medium and fine scotchbrite wheels before being polished in the same way as the blade. The use of the scotchbrite wheels turned out to be a mistake as they rounded over the precision-made opening in the guard so the blade no longer fit tightly into it. In the end this wasn't a problem as I was able to position them correctly before gluing but it's definitely something I'll do differently next time.

The assembled dagger

The parts were all laid out carefully and cleaned with acetone, and then masked off and glued with epoxy resin, this is another thing I'll do differently next time. It turned out that removing the masking tape without marring the surface finish was extremely difficult, so next time I'll try letting the resin set to a more gloopy stage before putting it all together, and cleaning off excess with acetone before it fully sets. A heavy clamp was put on the back of the tang and hammered down to make that everything was snug, then the whole assembly was put into the process oven at 40C to cure for 4 hours (probably longer than necessary but I wasn't taking any chances after this much work)

The welded pommel

Once cool I used a dremmel tool to reduce the end of the tang to a stub less than 5mm diameter and 100mm long so that it could be fitted into a small peen block to retain it. Over to the metal lathe, I used some scrap stainless steel we had to make a small button-like peen block about 5mm tall and 20mm wide with a beveled edge. Once that was made and cleaned it was time to use the TIG welder to secure it onto the end of the tang. This isn't a common method as it's more usual these days to use an oxy-acetylene torch to heat the end of the tang and hammer it into a taper in the peen block, but the lab doesn't have an acetylene torch for safety reasons and this worked quite well. The end of the pommel was then polished like the rest of the dagger.


That completed the manufacturing of the dagger so it was time to move on to making a mounting board for it so it could be displayed. I started with some timber from an old hardwood desk that I salvaged. It was cut up into usable planks with the table saw and band-saw so that I could work with it reasonably easily. I then used the router table to put finger joints into the edges of 5 of the planks so that they could be glued edge-to-edge and still be reasonably strong. This left a nice flat hardwood board which has a lovely warm colour to it and large enough to mount up the dagger.

The assembled dagger

I designed the shape of the mounting board in OpenSCAD with convex rounded top and bottom and gently concave sides, then laser cut that shape out of some scrap polypropylene that was laying around in order to use as a template to help shape the board. I screwed the template onto the back of the board and then it was back to the router table to use an edge-follower bit to cut the timber to shape, this actually took 2 tries as the first time I did it one of the joints exploded apart and flung a bit of timber across the room, fortunately the board I made was large enough for a second try. Once the shape was properly cut out I changed the bit to an Ogee cutter and put an elegant curve into the edge of the board so that it would resemble the kind of mounts that are normally used for trophies or ancestral weapons. The board was then coated with 3 coats of a water-based polyurethane varnish with sanding in between coats, this didn't give as high a shine as I was hoping for but with a little wax polish it still looks pretty good. Next time I'll probably try using either Tung oil or french polish to get a higher shine.

The Plaque

The next job was to make some clips to hold the dagger onto the mounting board so I opened up SCAD again and designed some spring clips that screw to the mounting board hold the dagger securely. They were 3D printed in carbon-fibre reinforced filament and bolted to the board with black-japanned bolts, the first clips I made broke as they were too stiff and rigid to fit the blade into without snapping so I re-designed the to be a little thinner and re-printed. The final touch was a small engraved brass plaque made using the boxford CNC milling machine. The dagger and it's mounting board has now been installed in the lab above the main stairs, where it will stay for a few months before I take it home.