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Bending Sides with Silicone Blankets

Bending Sides with Silicone Blankets

by Michael Keller

from his 1990 GAL Convention workshop

Originally published in American Lutherie #25, 1991 and Big Red Book of American Lutherie Volume Three, 2004



Althrough I attended the 1977 Guild convention in Tacoma, I exhibited my instruments for the first time at the following year’s convention in Winfield, Kansas. I visited Stuart Mossman’s shop while I was there, and I saw the side-bending mold that he had. It must have cost a fortune. It was about the size of a Volkswagen van standing on end, and it had all sorts of hydraulic pumps and pistons. In a production shop that kind of tooling might make sense, but for a small shop like mine, making twenty to thirty instruments a year and bending wood for repairs, I don’t need that kind of investment.

I bent sides for years over a hot pipe I bought at Lewis Music in Vancouver, B.C. I had to work at a regular job and save money for quite a while before I could afford to buy two Overholtzer side-bending molds. A friend of mine had a custom mold made by the Overholtzer company, and it cost $1,000, I believe. That’s a lot of money. I can bend guitar sides with either a hot pipe or a cast mold quickly and accurately, but I am in this to make a living, and if I can save time and money I will do it. That’s why I prefer my new method. By the way, would anybody like to buy two nice Overholtzer molds?

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Lute Rib-Cutting Jig

Lute Rib-Cutting Jig

by Robert Cooper

from his 1984 GAL Convention lecture

Originally published in American Lutherie #4, 1985 and Big Red Book of American Lutherie Volume One, 2000



The lute I brought with me today has a half-round cross section. In such an instrument, each stave is identical in size and shape to its neighbor. A set of these ribs can be cut quite efficiently on a jig I made for use with a router fitted with a small circular saw blade.

The main section of the jig is a solid wedge of wood, like a slice of apple. Or more like a slice of a pear.

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Ren-Shaped Precision Mold Material

Ren-Shaped Precision Mold Material

by Ed Beylerian

Originally published in American Lutherie #21, 1990



The demand for ever-increasing quality in end-use products has generated a concurrent need for improved modeling materials. Patterns and molds constructed from traditional materials such as laminated wood and plaster cannot maintain the precise tolerances required by model makers in the automotive, aerospace, foundry, and prototyping industries. With Ren-Shape 450, models can be built with a more stable medium, using precision numerically controlled (NC) machining equipment.

I obtained a 2"×16"×60" board of Ren-Shape from Ciba-Geigy corporation, as well as the laminating compound and the repair kit. Ren-Shape is about the same hardness and density of a medium hard wood, and a tan color. The setting time of the two-part laminating compound is easily controlled by the amount of hardener used, and can range from one to six hours. The repair compound sets overnight.

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Applications of the Silicone Heating Blanket in Violin Making

Applications of the Silicone Heating Blanket in Violin Making

by George Borun

Originally published in American Lutherie #34, 1993 and Big Red Book of American Lutherie Volume Three, 2004



In American Lutherie #25, Mike Keller describes how he uses silicone heating blankets for bending guitar sides, and mentions an earlier article in Fine Woodworking. The potential of these devices for use in violin making became obvious to me, and with some experimentation and adaptation, I’ve developed specific applications for the violin maker.

Silicone heater blankets, also called flexible heaters, are available from two sources, with a number of standard sizes in stock at each company: Watlow Electric of St. Louis, Missouri (www.watlow.com) and Benchmark Thermal of Grass Valley, California (www.benchmarkthermal.com). Watlow markets through distributors. They have a large selection of stock sizes up to 35" long. Benchmark has a smaller stock size selection, but their prices are considerably lower. They will make any size you wish, but that adds to the cost and delivery time. Stock maximum length is 20", but this is more than long enough for violins. In bending bass ribs, I use two 10" wide blankets for the longer pieces, and only one for the center bout. The best units are 4W/sq.", rather than the 2W models. This type will get up to 500°F in a couple of minutes. Product catalogs are available which list the various sizes.

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Blackboard Eraser Polisher

Blackboard Eraser Polisher

by Michael Dresdner

Originally published in Guild of American Luthiers Data Sheet #288, 1984 and Lutherie Woods and Steel String Guitars, 1998

 

I’ve been using a blackboard eraser to do final dressing on my frets. I take this nice soft eraser and a piece of 600 paper and go across the fretboard. It’s beautiful; it just follows the curve and gives you a nice even rounded top. This is for polishing, after you’ve shaped the frets with files. ◆