Wade's M-10 has a very heavy collar. I think we found the rivets, which had been clipped to a flat point were 5mm in length with massive deformation.

Here's a detail from a German mail shirt at the Met showing the front and back on the latten edging of a long sleeve. The latten rings often show the tooling better, since they suffer less from corrosion and can't be heated after assembly. The split on the front around the rivet point is evident, showing the drift came to a chisel edge, more like a screwdriver than an awl.

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Met 14.25.1540

Well as we are looking at tiny links, just for some light relief here is some mail in the opposite direction I've just driven by in the Swiss Alps on my way to Churburg (yes, I'm so excited my wife is thinking of sedating me and leaving me by the side of the road)

Int. diameter about 3ft.....

I've taken a load more from other sites so will post up as soon as i can.

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I think if you take your chisel and bevel the edges inward to a trapezoidal section narrowing to a near point, you'll be closer.

Eric,
Perhaps it's time to look at jewelry chisels or gravers?

I think that the chisel should cut a slot which is a good approximation of the shape of the rivet. To do more is a waste of effort and is more likely to split and ruin the ring. To do less makes it difficult to seat the rivet.

That said, a "good approximation" might not be quite as wide as the rivet is thick at the place where the chisel exits the ring. If the rivet is obliged to spread that exit slit a little it might be more inclined to stay seated while the mailmaker switched over to the closing tool.

Mac

Something like this. Blacksmiths call this shape a "cat's tongue". They use them when a hole is to be slit and drifted to shape in one heat. For mail purposes, it would have to be used cold, but it's all the same.

The point can not be literally the shape of the rivet. It has to be rounded a bit or it will be too fragile to do the job. The cross section near the point is an ellipse or lens. The section grades into something more rectangular for the base of the rivet.

[ Linked Image ]

You are not going to find anything like this commercially. For serious production, you would want to make it on tool steel. For experimental purposes, you can grind one out of a hardened masonry nail if you are careful not to draw the temper.

Mac

The holes in the rings I've photographed look more like the section of a wood chisel than a cold chisel. Commercially available gravers and blank stock is already appropriately sized.

http://www.riogrande.com/Product/GRS-GlenStee...670?Pos=13
http://www.riogrande.com/Product/GRS-GlenStee...669?Pos=17

I measured a number of the rings, most across the part of the rings without the rivet. It is complicated by the fact that they are usually a bit oblate in shape, not truly round, though I chose rings that were more round than others. These measurements are from the body of the piece, given in inches first and millimeters in parenthesis; .165 (4.19), .174 (4.43), .173 (4.4), .173 (4.41, must be due to +- range of the digital caliper), .167 (4.25), .180 (4.58), .172 (4.36), .174 (4.44), .172 (4.39), .173 (4.4), .172 (4.39). Then I did some across the rivet, .168 (4.28), .172 (4.38), .163 (4.15), .169 (4.31), and a last one across both axes, .168 (4.28) and .166 (4.21). Then I measured some of the thicker links on the top strip; .173 (4.4), .182 (4.63), .179 (4.55), and .184 (4.69). All a significant bit bigger than 4mm.

It's certainly more trustworthy figures than trying to measure a ring laying at an oblique angle from a computer screen! I suppose we would have to consult a statistician to find out how many rings we need for a statistical average to be valid, but I think you've done a good amount. A significant bit larger than 4 mm, and a more significant bit below 5 mm other than the reinforced area.

I really think hundredths of a millimeter is too insignificant to matter in this type of work, and have started to round to tenths. It reminds me too much of digital gas pumps measuring thousandths of a gallon.

For reference, the welded AZON mail used for butcher's gloves and such comes in two sizes:
0.150" (3.8 mm) outer diameter, and the one sold for re-enactor/ fencing/ etc. use being 0.210" (5.3 mm) diameter.
http://www.ringmesh.com/category_s/54.htm

The ID's are running very close to 1/8". My wrists are tiny. :)

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Eric,

I really don't think we are talking about an entirely different process, but only some refinements of the one that the modern riveted mail folks are using.

The "roll in" in the back is a bit excessive here, but with a properly shaped closing tool, that can all be brought to a nice shape.

The bulge on the upper side is far from a defect. It's really necessary to get some metal in the right place to be pressed into shape during the final closing. We can not generate enough pressure for the metal to flow "up" into the shaped cavity of the closing tool. The rivet bulge can only get smaller, so it's best to start with it higher then you need.

[ Linked Image ]

Mac

I thought I would but money where my mouth is this morning, so I spent some time experimenting with mail.

Here is the punch I made from a masonry nail. It differs from the tool I sketched the other day in having a gradual lead in to the point. This will make it easier to resharpen. I also re-did the heat treating because these nails are really a bit too soft as they come.

[ Linked Image ]

Here are two views of the point.

[ Linked Image ][ Linked Image ]

For the rivets I used the same wire as the rings, flattened under the hammer and cut to a point with a nipper.

[ Linked Image ]

I jammed the rivet into the slot and broke it off at the pre-nipped line. I never tried this before, but it seems to work pretty nicely.

[ Linked Image ]

After pressing the rivet home, it looks like this.

[ Linked Image ][ Linked Image ]

The final closing was a bit disappointing, but I knew it would be.

[ Linked Image ][ Linked Image ][ Linked Image ]

I used this old tool I got from Steve Sheldon many years ago. The faces are too flat to give a sexy final shape to the overlap, and the central depression is sized for a much larger ring.

[ Linked Image ][ Linked Image ]

So, it seems like the next thing I must do is make new tooling for closing the rings. That's a lot more trouble than just making a slitting punch. I will have to think on this for a while and see if I come up with something simple.

Mac

Grinding or cutting those end cutters is a bear. Get it down to about a 5 mm square end, and maybe groove through the center of it with the edge of a triangular file?

I made up a hand held punch for finishing the upper surfaces, and prepared a slightly concave spot on the corner of a steel block for the backs of the rings to sit.

The results are an improvement.

[ Linked Image ][ Linked Image ]

I'll go back and look at the pics of the real stuff and see if I can figure out what direction to go in next.

Mac