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Monthly Archives: May 2010

My cello is making progress, even if rather slowly. I’ve just closed up the box, which is a step that requires a lot of clamps to hold everything in position while the glue sets.


And here’s the problem: where to find enough clamps. One solution is to buy or, cheaper, make spool clamps for the job. But these clamps are less than perfect because the force they exert operates at the edge of the plates rather than directly over the ribs. For clamps that put pressure in the right place, you have to buy a set of the dedicated cello clamps made by Herdim®, which, I’m told, are easy to use and work well. Unfortunately each of the Herdim® clamps costs about 15 Euros, so getting equipped with the 40 or so that are needed for a cello is quite expensive.

Partly out of meanness and partly because I enjoy making my own tools and jigs, I devised this alternative. The photographs make it fairly clear how the clamps are constructed and instructions are probably unnecessary. But perhaps a few details will be helpful. The clamping force is supplied by a wing-nut on 6mm studding. I made at least half of the clamping length out of aluminium tubing so that the clamps were as light as possible. It’s important that the aluminium tubing has an internal diameter only very slightly greater than the diameter of the studding so that the upper part of the clamp slides smoothly, but without play, over the lower part. The clamping pads are mahogany but, of course, any hardwood could be substituted. When making these pads, it’s a better idea to work a rebate into a length of cross grain mahogany and then saw it up than to craft each one individually. The pads are lined with cork that has been glued on in a profile that puts the pressure directly over the ribs. I used polyurethane glue to set the tubing into the clamping pads and to cement the studding into the aluminium tubing but I should think epoxy would work equally well.

The same principle also works for shorter clamps. The one below is designed for crack repairs. Shallow cleats are temporarily glued either side of the crack, which the jaws of this clamp can grip to close the gap.

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At the Easter Instrument Making Course at West Dean this year, I had the pleasure of meeting Wouter Hilhorst, who was making a viola. Apart from admiring the precision and delicacy of his work, I was also interested to see that he had made his own planes, 2 of which were in the Japanese style. He let me take a quick photograph – see below.

We’ve recently had an email correspondence and he’s sent me some better photographs, and some details of how he made them. He gets the blades from the German company, Dick, and recommends their Japanese blades writing:

They are laminated and can be honed to a very sharp edge. As you probably know, blades for larger Japanese planes taper in thickness and wedge themselves in the more or less resilient oak plane bodies, which works surprisingly well. The small blades from Dick aren’t tapered in thickness, but only slightly in width. When I made them I thought I would wedge them widthwise, but the little recesses which grip the blade on both sides are enough, just by friction (although I had to glue two little strips of paper in the recesses of the smaller plane). The blade needs some space widthwise to be adjusted laterally.

He makes the planes from European oak or boxwood and chisels them out of a solid block. This is a technique that I intend to re-visit. All the planes that I’ve made recently followed the Krenov method in which you start by sawing two slices off the block to make the sides of the plane, shape the bed and throat from the middle section, and then glue it back together. There are some photographs of this method of construction here and here.



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