Saturday, October 18, 2008

Getting To Know Roubo -- Leg Vise Tweak

When I made my Roubo bench I used a roughly 5" section of 3/8" steel rod as a pivot pin for the parrallel guides on both leg vises. I don't move the pin often, but when I do it's a bit of a pain to grab that little pin, especially when the vise is almost closed.

I'm pretty sure I got this idea from a picture of Lie-Nielsen's new Roubo bench, posted on Woodworking Magazine's weblog. The area of the picture was a little blurry, but it planted the seed, and I went with it. So credit to Lie-Nielsen Toolworks for this idea.

So I lengthened the pins, then inserted them into a turned handle. The pins are now much easier and quicker to grab and reposition.

The pin for the sliding vise is a bit longer since the rear chop on the slider is wider.

After using the handled pin a few times I realized that some thought and effort was required to avoid over-inserting the pin in the parallel guide's hole. Pushing the pin in too far places the handle between the jaws and prevents the pin from seating flatly against the leg. If part of the handle goes past the edge of the leg, the parallel guide would mash that part of the handle into the leg when clamping.

The solution was to stop the pin at a fixed location without interfering with the function of the pin. Anything larger than the pin's diameter would't work. My solution was to drill through each pin and drive in a 1/8" roll pin.

This makes changing holes truly brainless. It's impossible to over-insert the pin.

Changing pins in the parallel guide is quicker and easier than ever.

Tuesday, October 14, 2008

Tradition meets technology

A few years ago John Herin invented a new type of geared tuner for stringed instruments that he calls the "Peghed". It's unlike any other geared tuning peg. It actually looks and works just like a real wood peg, without all the real wood peg problems. The device uses a system of planetary gears housed inside the peg's aluminum shaft. With the 4:1 gear reduction that these provide, fine tuning is effortless. And the pegs stay put without all the idiosyncratic movement required with wood pegs. When I first saw these pegs in a local music shop I was really impressed by the function of the pegs, but not so much by the looks. The shaft looked fine, but the head was a rather crudely fabricated black plastic material (pictured above) that didn't look or feel like ebony, let alone any lesser wood. It reminded me more of phony leather than wood. So I wrote them off, thinking that I would wait until another option came along. I should clarify that the pegs I saw in the local shop are actually Perfection Pegs, which use Herin's mechanism, but marketed under a different name. I recently became aware of a major change in Herin's product through my friend and fellow oud enthusiast Mike Malek. During a recent visit with Mike, he showed me an entire box of these new tuners headed to a luthier in Egypt. I was really impressed. Here's the difference. The heads of these pegs are actual wood. Ebony, in this case. When a recent customer asked if I could install these new pegs on his instrument, I jumped at the chance. I sent a set of my rosewood Nahat-style pegs to Herin, and he worked his magic.

Herin separates the head of the peg from the shaft, and uses a CNC lathe and mill to excavate a complex mortise in the end of each peg head.

Then part of the mechanism, which matches the shape of the mortise, is glued into the head.

And here's the interesting part. The shaft of the peg which is visible outside the pegbox walls, is fabricated from anodized aluminum to mimic the color of the rosewood heads. The Pegheds are also quite light for a geared tuner. 12 of the rosewood Pegheds weigh 108 grams in their raw state (the extra long black section of the shafts will be trimmed shorter when installed), while 12 rosewood pegs weigh 91 grams. That's about 1.5 grams difference, per peg. In other words, 12 Pegheds are about equivalent to 14 rosewood pegs. Not a huge issue. Up close, the pegs won't fool the discerning eye. But these Pegheds are a far cry from the plastic-banana pegs that I saw in the music shop.