Mandrel!


This weekend I’ve got a guest coming to the forge; we’re going to try to make him a seax. It’s going to be a lot of fun watching someone else work while I take pictures and drone advice at him.

Meanwhile, I have been pondering if I want to change the way I usually mount a handle. I’ve been doing it the same way for 20+ years, now. Maybe it’s time to experiment a bit. I spent a few hours messing around trying to sculpt some things in clay, so I could see what they’d look like. It turns out I am not a sculptor. Finally, I decided I’d just make a couple pieces out of metal and see how they looked, then figure out how to duplicate them if I liked them.

I’ve also been pondering things like guards and pommels, which I normally don’t do – but a seax has a guard, so that’s something to think about. I had the idea we could just flatten down a piece of gooby and cut a guard with a coping saw. Ha ha ha, I crack myself up: the piece of gooby I picked was wrought iron/1095 high layer damascus and the coping saw blade polished a spot, got warm, and died. Have I mentioned that wrought iron is really tough stuff? And it’s a doddle compared to something like S7 tool steel.

Eventually I resorted to the tried and true method of chopping big hunks away from it with a cutoff wheel then roughing it with an angle grinder, and then detail-sanding it on the belt sander. A little piece like this is a pain to work with because it’s got no thermal mass and heats up pretty quickly. Fortunately, my dunk-bucket was near freezing temperature so it cooled off pretty fast. After an hour or so I had a pommel cap of sorts and a guard of sorts.

One of the other ideas I’ve been thinking over is casting bronze. So I’ve decided to make an archive of all the guards and pommel caps that I design. I’ve been making little silicone molds from the pieces, that way I can cast beeswax in them and do a greensand open mold casting (or get some investment and make a really nice mold). I am not sure if this is a good idea but it may save me hours someday.

Then I started noodling with the idea of forming a copper band that sort of overlapped like a shaker steam-formed wooden box. Maybe I could put a pin in it if I get fancy. So I asked myself “what would Torbjorn Ahman do?” and decided to make a mandrel. I took a chunk of S7 tool steel (heinously tough stuff) from my metal collection and spent about 2 hours grinding it and shaping it into an approximation of the handle where the cap would fit.

I left it nice and square so it could go in a vise. Admittedly, this is the sort of thing that a milling machine is for, but I don’t have the skill to do a shape like that, freehand. It’s not round, so using the lathe to clean it up isn’t an option, either. Besides, I’ve never dared attempt to lathe metal.

A nice thing about working something like S7 is that it’s very hard to screw up. Because, to “screw up” you have to remove a lot of metal, and that’s not easy – it’s all slow going, which makes it thoughtful and relaxing work. I popped the forge on and heated the mandrel and quenched it, then heated it back to golden color to temper it. It’s basically so tough, now, that about all I can do is polish it. So, I did that.

There’s a problem with this approach, which is that I’m standardizing the size and shape of my handles, if I use the mandrel for shaping end caps. Perhaps I will make another or two someday. It is hard work but it’s meditative and relaxing to make sparks fly.

Then, I took a strip of paper and measured the length of stock I’d need, cut a piece of copper, clamped the mandrel in my vise, and held one end of the copper in some flat pliers while I tapped it into shape with one of my little hammers. As I got the metal most of the way around, I ground down the point where it would overlap (a bit) so it wouldn’t make a bulge. After that, I just hammer-stretched it and tightened it by stroking the hammer-strikes so they pushed the metal over and around. Using a fine file, I de-dented it with little gentle strokes, then switched to sandpaper: 600 grit, 1000 grit, 3000 grit, and then steel wool. It looks lovely, I think, but it may be a bit too chunky for a sushi chef’s knife. There’s an easy way to find out, though!

Since I might want to cast these in bronze or sterling I made a silicone mold of it, too. Before I put it in the mold, though, I modified how the mold will come out, by altering the object with clay. Sneaky, huh? I filled in the lap-line by packing clay into it, so when it’s cast it’ll look like it was brazed. Then, I made a cap-piece by putting the wrapped piece down and tamping clay into the base of it with a square-ended rod. It that works, for castings, it is going to be so much easier than cutting and fitting a copper base, because the copper base should probably fit on the inside of the piece, not the bottom (so the braze-lines are less visible) – that will mean a bit of filing and fitting.

A little while ago I decided to go down to the kitchen and make some tea, and I discovered that I hadn’t done a good job setting up the mold-box. This is what I call an “unauthorized silicone excursion.” It’ll peel right up in the morning but I’m a bit sheepish. I’ll just top off the mold box and the mold will be fine. I have another silicone mold compound from smooth-on, which is supposed to hold strength and shape up to 500F, which means it can handle light casting like tin or sterling. If I can directly cast those caps, that’d be great. There’s an alloy called “brittania metal” (mostly tin, I think) that is also low temperature and looks like sterling. Best of all, it’s $20/lb. I really want to try bronze or shakudo.

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I have a trip to Stuttgart next week (speaking at IT-Defense conference) the 2-9 and I’ll have my shop-guest until sunday, so I may not reply to comments or post on my usual schedule. After that I have another trip to Luxembourg and then California.

Comments

  1. rq says

    In picture four? That shape? If you made some slight adjustments to the width of the band opposite the overlap, it would be a beautiful and elegant ring. It looks like it has enough heft to sit comfortably on my middle finger.

    Also, safe travels. The jetsetting lifestyle sure is glamourous!

  2. says

    rq@#1:
    I actually have a ring-maker’s mandrel somewhere. Back in 2016 I made a couple of rings for a friend. Fun project. Same process: you get your materials and sort of tap and whack them until they curve around the mandrel, then braze them into place.

    It might be fun to include a matching ring with a knife, someday. But my workmanship in that area needs to level up dramatically before I’d be able to produce something someone would want to wear. That goes into the idea-bin, though, and it may come out again later.

  3. voyager says

    I hope we’ll get to see a few photos of the seax project. It sounds interesting.
    Also, I hope the globetrotting all goes smoothly. Enjoy your travels.

  4. kestrel says

    So cool.. that shaped up really nicely. That’s going to be a very interesting project. Making a ring to go with a knife is a great idea, I suppose most of the equipment you have would do that just fine! You sure don’t need any fancy equipment to make a ring especially a fabricated one like that.

    You mention that the silicone mold will stand up to 500F and suggest casting sterling silver in it; I hope you’re aware the melting point of sterling is 1,640F…. I’m afraid your mold might not like that very much. However pewter would work just fine. (Or did you mean 5,000F?)

  5. rq says

    To be honest I already want to wear it. :D I’m not big on fine jewellery, I like something with heft.
    The idea of matching knife-and-ring is actually pretty awesome. Maybe one day.

  6. says

    @kestrel – I’m not sure what’s going on there and will research more carefully before I try anything. 99% likely I will sand cast first because that process is very familiar from my soap-making efforts.

    I want to avoid wearing hot bronze. I really do.
    When I was a kid I got some burning plastc on my hand and I still carry the mark and remember the pain.

    What really scares me is liquid platinum, which I will not get close to again.

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