This is the tool I designed and built over 20 years ago for cutting purfling grooves.
In my quest for the perfect jeweler’s saw blade for sawing out f-holes, I once landed the world’s last supply of these antique blades, defunct blades from a closed hardware store, bought at a now-closed tool store in downtown Chicago. The brand is Gilbert, and I tracked them down to around 1890 or so. They’re perfect for the job, sawing a wide kerf with lots of turning room, quickly, but not making a mess.
Notice that they appear to be made by a machine-driven chisel upsetting the edge of a strip of steel that’s then hardened after the teeth are cut. From the contour on the top of the teeth, I decided they probably started out as wire which was rolled flat. The photo is quite magnified: the height of the blade, from the bottom to the tops of the teeth is a little less than 1.5mm, and there are around 20 teeth per inch.
I have wire! I have chisels! Just for fun, after seeing a video on making rasps (a similar process to the way these blades were made), I decided I’d try making a blade the way they might have done it 300 years ago, by hand. I took a piece of soft iron wire, 1mm thick, and pounded it flat, for a start, then I started chopping.
OK, so I’m not ready for prime time. I can see the similarity to the original, but it’s harder than it looks. Before I could finish a whole blade, I cut all the way through, accidentally. I posted this photo on a forum where a member of the rasp company was posting: he noted in response that it takes several years to train someone to cut a rasp to their standards, and I believe him.
Here’s the video that inspired me, if you feel like trying your hand at rasp-making.
Before “sharpening” on the left, after on the right. I guess this wasn’t such a hot idea!
There is a simple shop method for sharpening files that’s mentioned in more or less detail all over the web. It’s done by dipping the files in acid for an hour or more, which supposedly etches away metal, sharpening the edge. However, as the process moves on, heat is generated, and that heat concentrates at the thinnest places in the metal–the sharp edges–and speeds up the process there. The result is as on the right in this microphoto: a file which feels much sharper because the surface has become greatly roughened. But look at what’s happened to the cutting edges: they’ve become blurred and dulled! The fresh, grainy roughness made that file feel like it was really going to hog wood, but in reality it mostly made a lot of grinding sounds, producing very fine dust, and hardly cutting at all.
There’s one shop, Boggs Tool and File Sharpening Company, that really does the job right, though. I sent them a batch of files many years ago, and they came back sharper than new, as Mr. Boggs had promised me. The improvement was genuinely amazing. I suspect he uses a similar process, but adds a step to concentrate the etching where it will make the edges sharper rather than duller. I may have figured out what that step might be, but I think that the next time I want an exotic $30 file sharpened, I’ll just let the expert do it right, rather than destroy it all on my own.
Over at the Maestronet forum I posted this photo of the collection of gouges I use, and I’m going to repost here what I wrote there.
It’s easy to want to buy everything, but then you have to keep it all sharp. Here’s the list of what I regularly use:
From the left:
30mm #7 for roughing, inside and out. The total length is 355mm
25mm #3 for finishing, inside and out.
19mm #7 for the edge around the c-bouts. Sometimes I use one of the scroll gouges.
21mm flat: a HSS knife blank with fingernail sharpening for where I need something almost flat
12mm #5 for as much of the head as I can manage
10mm #6 for when the previous is too flat
8mm #7 likewise
5mm #8? likewise
6mm incannel drill, probably #9 or so, for hogging out inside the pegbox
If you look at Cremonese scrolls you’ll see that they only used a couple of gouges to do the whole job, so that’s what I do too. They are all sharpened to fingernail profile. On the knife blank that lets me use it bevel up for flat paring (sides of pegbox) and flipped it acts as a very flat gouge (for part of the first turn above the pegbox, and the transition between the two).
The last one is sold as a violin tool. As with many violin tools, it doesn’t work very well (the outside isn’t really round and the walls are too thick to bore easily} and I probably should buy a 6mm #9 and sharpen it in-cannel.
I wasn’t thinking about chisels when I shot this photo, but my chisel set is relatively simple: a 1″ that I use only for fitting cello necks, a 1/2″ for most other work, and a 1/4″ that I use in tight spots, rarely. All of these are quite long, not stubby hardware-store chisels. I also have a very narrow hook/chisel that’s about 1mm wide, for clearing out purfling grooves.
Over the last few years I’ve been messing with a contractor’s laser level to show violin arching more clearly. It’s a variation of the maker’s idea of using a ruler and light to cast a shadow on the arch while shaping it, as pictured above, and initially I used a series of photos, and then went to movies for the same purpose. There’s more from the laser, and a movie, at this post.
Finally, I got the idea of a way to mix both together, so that the entire arch would be mapped in one shot, of higher resolution and sharpness.
If you have an outline of the violin so that you can scale out the widths, and just this one photo, you can make accurate templates. It’s simpler than the old way of spending all afternoon cutting templates off the real violin with thin slips of wood, or using a carpenter’s contour copy gauge. Now, if I have ten or fifteen minutes with a violin, I can extract all the data I need to make a copy of it, from just a set of drawings and photos.
The final step in this process for me, since I’m only copying Cremonese models, is to redraw the arch without 300 years of distortion. This requires a bit of reverse engineering to figure out what they were thinking then, and what their originals must have looked like when they weren’t so bent out of shape as they are now, through three centuries of strings tugging the parts of the violin in different directions.
In conjunction with Canadian violin maker Quentin Playfair, who originally outlined the role of curtate cycloids in Cremonese violin making in a STRAD magazine article some years ago, Stephen Mann developed free computer software to draw the appropriate curves without any fuss. All that’s necessary to generate the cycloid shape is the distance between the low spots of the scoop around the plate and the height of the arching, at the location for where you want to make a template.
Even if you’re not making a violin, the software is fun to play with: as you change parameters, you can watch the curve change in real time. It’s an interesting shape which appears to change radically as you approach extremes, yet all of the apparently different versions are mathematically related.
There are links on the same page as the software if you’ll like to learn more about these interesting shapes and their associated math. Those of us who once were children may remember the spirograph, or may even have generated cycloidal curves using buttons and a pencil
A bit irrelevant to violins, but I got a few of the best tools that I use in my violin making from my great-uncle. He was a wagon maker in his father’s factory around the turn of 1900, and this is the type of thing he made:
This is the outside courtyard of his factory, in Toledo …
They had an opportunity at one point to sell out but didn’t really think that the horseless carriage was going to be much competition, so the family kept the factory. Probably that was a mistake.
A friend of mine whipped up some jigs to permit him to make quick neck grafts in blocks of rough, uncarved wood that he could then carve so that his new “antique” instruments would have authentic neck grafts in them. When he came to visit me, he brought this dummy graft test made of a couple of pieces of construction lumber. Normally a neck graft takes hours to complete, but this setup makes one in a few minutes. Of course you could never safely do something like this with an valuable old instrument!