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Mask for Belt Sanding

Mask for Belt Sanding

by John Calkin

Published online by Guild of American Luthiers, March 2024

 

My 6×48 belt sander is my favorite and most used machines, though getting the most out of it didn’t come easy. It takes a knack to use one accurately, and that took years to develop. Perhaps most importantly, I learned to join plates and sculpt necks, saving myself scads of time over the years.

This tip is about sanding parts on nearly completed instruments. It can be dangerous because the plates are already as thin as desired. In this case I needed to take down the end blocks of a dulcimer to the level of the plates. I had already shaped the sides of the blocks using a disk sander and sanding blocks. I used a scrap of poster board to mask the plates as I took down blocks to meet the plates.

The end blocks weren’t that much oversize. A hand plane might have done this job as fast as my belt sander, But I never use handtools if a machine will do the job.

Whew! I cut it close on this one, but it’s OK. The back of this dulcimer was already thinner than I liked.

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The block on the bridge end has to be larger to make room for some sort of string fixtures. There are also blocks inside the dulcimer to support the end blocks.

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The mask doesn’t have to be fancy or cover the entire plate. Sanding the block is done in quick steps with visual checking at every step.

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No sweat this time. All of the hand pressure on the sanding belt is applied to the block. I usually keep 80 grit belts on my sander. Sixty-grit would last longer and cut faster but the scratches require more work to remove.

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The abrasive barely touched the mahogany on this end. Most belt sanders of this size come with a 9" disk sander attached, but right from the factory mine wobbled badly. It was also frequently in the way, so I dismantled it. I considered returning the machine to Woodworker’s Supply, but repacking it would have been a lot of work. They still sell this machine. If they haven’t improved I wouldn’t buy it again. Standing the belt 90 degrees to the supplied work table turned out not to be a big deal, so I didn’t miss the disk sander very much. ◆

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Potassium Dichromate, Oxalic Acid, and Carnauba Wax

Potassium Dichromate, Oxalic Acid, and Carnauba Wax

by Jeffrey R. Elliott

Originally published in Guild of American Luthiers Data Sheet #52, and #55, 1977 and Big Red Book of American Lutherie, Volume One, 2000



Potassium dichromate. European luthiers commonly use potassium dichromate to give that nice, brown “aged” look to lighter, newer woods. It can be used by itself or mixed with aniline dyes for additional color tints. Primarily it has been used to darken the interiors of violin-family instruments, although I know of many who have used it on the exterior to darken spruce and maple. I have used it both inside and out to create a “naturally aged” looking wood on guitars.

Potassium dichromate is a chemical activated by light from the sun, sunlamp, or infrared lamp, but direct, natural, full-spectrum sunlight is best. Beware: Indirect light will not activate it, and the solution will tend to color the wood a murky green. The solution is rather weak — two tablespoons to one gallon of water. It can be applied by brushing or by wiping it on with a cloth (wear gloves). Although I have never tried it, I imagine a spray method would work as well. Whichever method is used, a light, even coat is recommended.

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Meet the Maker: Kevin La Due

Meet the Maker: Kevin La Due

by Cyndy Burton

Originally published in American Lutherie #81, 2005 and Big Red Book of American Lutherie Volume Seven, 2015



The fall colors of upstate New York were in full regalia as my sister and I drove towards Binghamton, New York, to meet my niece for lunch. She had just started a new job at nearby Vestal High School, where she’d met a teacher named Kevin La Due, who is teaching high-school kids to make guitars. It sounded like a story asking to be told.


Please tell me about your program.

I teach two sections of lutherie per year, one each semester, which distills down to about sixty class hours each semester, not really enough time to make a guitar. Most students work extra time before and after school and during their free class periods. Although about fifty students apply, we only have room for fifteen seniors at a time because of facility, prep time, and budget limitations.

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This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

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Router Trimming Attachment

Router Trimming Attachment

by James Gilbert

Originally published as Guild of American Luthiers Data Sheet #135, 1980

 

This attachment plate is used on the Dremel Moto-Tool in place of the regular router base plate. The other end is drilled and slotted to fit the Sears router attachment part #25731. The Sears attachment is used for laminate trimming. It has an adjustable slide and a roller guide to follow contours easily.

The full size drawing below could serve as a rough template for cutting and drilling a piece of 3/16" aluminum.

The only modification that I have made to the manufactured units is to drill an extra hole in the Sears attachment for securing it to the base plate. This way it can still be used on a regular router. ◆

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Shop-Made Bandsaw Dust Port

Shop-Made Bandsaw Dust Port

by John Calkin

Published online by Guild of American Luthiers, September 2021

 

My old bandsaw was made before dust ports were added to every power machine, so I made one out of wood. It's a close copy of the heavy-gauge steel cover for the lower wheel but made out of light plywood. The dust port itself was purchased and screwed to the cover. A mahogany interface to accept the 3" vacuum hose was made to fit the port. The sides of the cover were kerfed to permit easy bending to match the original metal cover. I think the rest of the construction is self-explanatory. ◆

All photos by John Calkin