Posted on June 13, 2024May 15, 2025 by Dale Phillips Fretboard Slotting with a CNC Router Fretboard Slotting with a CNC Router by John Svizzero and R.M. Mottola Originally published in American Lutherie #98, 2009 Lutherie shops with CNC machines use them for a number of applications, some of which are discussed in the article “Desktop CNC Machines” in AL#77. We (authors Svizzero and Mottola) met at meetings of the New England Luthiers and began comparing notes on our shop-built CNCs. Svizzero’s full-sized machine uses Porter-Cable routers as spindles, and Mottola’s desktop machine uses the Proxxon grinder. We have each been using CNC routers in our own shops for slotting fretboards. By CNC routing standards, fretboard slotting is a slow operation due to the small diameter end mills used (typically .022" to .025"), but in our small shops we have found slotting in this manner to be both cost effective in terms of time and to offer some advantages that other slotting schemes do not. With a suitable CNC machine already in the shop, it is possible to experiment with CNC fretboard slotting with a small investment in tooling and time. Our experiences may help others get over some of the startup problems. Become A Member to Continue Reading This Article 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. If you are already a member, login for access or contact us to setup your account.
Posted on June 6, 2024May 28, 2025 by Dale Phillips Questions: Stainless Steel Rusting Properties Questions: Stainless Steel Rusting Properties by Peter Dyer Originally published in American Lutherie #58, 1999 Peter Dyer of Winters, CA has perhaps the last word on the subject of stainless steel and its rusting properties and the Universal Side Bender: The Metals Handbook, Desk Edition, published by the American Society for Metals (6th printing, 1991) says, “In atmospheres free from chloride contamination, stainless steels have excellent corrosion resistance. Types 430, 302, 304, and 316 normally do not show even superficial rust. Some rusting may occur in marine atmospheres or in industrial exposure where surfaces become contaminated with chloride salts.” So, if you’re building guitars and using 302 or 304 stainless on the Universal Side Bender, absent the conditions described above, don’t worry about rust. I hope that this resolves any confusion generated by the seemingly contradictory statements earlier. ◆
Posted on June 6, 2024May 8, 2025 by Dale Phillips End Mill Cutters End Mill Cutters by Bruce Scotten Originally published in Guild of American Luthiers Data Sheet #149, 1980 and Lutherie Tools, 1990 The use of routers to cut channels for binding, purfling, and rosettes is quite common. One problem associated with this tool is tearing and chipping caused by the use of standard router bits. A simple solution is to replace router bits with end mill cutters. Their advantages are: the increased number of cuts per revolution (4, 6, or even 8 flutes or edges, compared to 1 or 2 on router bits); plus the right-hand cut, left-hand spiral option which cuts with a downward motion that prevents the hairing and tearing caused by right-hand spiral lifting, and the slapping effect of straight router bits. End mills are more expensive than Stanley or Sears router bits. Solid carbide, 1/4" shank, 1/4" cutter, right-hand cut, left-hand spiral end mills are about $20. However, decreased down time and improved product performance make end mills a sensible alternative for the serious luthier. End mills are used more in metal working than wood working. Therefore any machine shop should be able to direct you to a jobber specializing in cutters. Johnson Carbide products in Saginaw, Michigan is a reliable source for end mills if you have difficulty locating them in your area. ◆
Posted on March 3, 2024May 13, 2025 by Dale Phillips Miter Slot Sled Miter Slot Sled by John Calkin Published online by Guild of American Luthiers, March 2024 This jig is more fallout from the week I spent in the last century in a class taught by Charles Fox. Jigs with clamps such as these have been all over my shop since then. On top, the jig is nothing more than a panel of MDF, two lengths of 1/2" threaded rod, a pair of knobs, and two “jaws” cut from steel flat stock. The jaws were placed in a vise and one end was bent into a slight hook with a hammer. As you will see, aluminum might have been a better choice. The underside of the jig is nothing more than randomly placed, recessed tee nuts and a wooden runner that fits nicely into the miter slot of the table saw. The runner left the panel overhanging the blade slightly so that a zero-tolerance saw cut could be made. All layout is done on the object to be cut. Lines are placed on the edge of the jig, clamped down, and gently run through the blade. Rough lumber can be given a clean edge as long as the dimension is within reach of the saw blade. BEWARE OF THE BLADE TOUCHING THE STEEL JAWS. THE RESULTS COULD BE DISASTROUS! Aluminum jaws make much more sense in this context. Note that helper blocks are needed to cut tall stock, in this case a pair of ukulele neck blanks. Make the cut slowly to prevent moving the stock, especially if the blade is less than newly sharpened. Since this is the maximum depth that the saw can cut on this jig, the threaded rods were marked for length with a piece of masking tape, then cut back with a hack saw. ◆
Posted on March 3, 2024May 13, 2025 by Dale Phillips 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. 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. 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. 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. 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. ◆
