Physics of Music PHY103 Lab Manual 2011Lab 3 – Making a Fretted Monochord Using the Tempered Scalemetal sleeveScrews go here to fix the tuner to the boardPhysics of Music PHY103 Lab Manual 2011Lab 3 – Making a Fretted Monochord Using theTempered ScaleEQUIPMENT and MATERIALS- Guitar pegs (Economy guitar tuners)- Wood board 8’ x 1.5” x ¾” (hardwood) or something thicker if pine - Guitar strings- #6 flat washers to hold string end- Pieces of wood, plastic and rubber to make bridge and nut pieces- 1” diameter drills, hand drills- Miter boxes, files, rulers, clamps, vices- Fret wire, Fret saw (that has width the same as needed for the fret wire)- Snippers for cutting fret wire flush to the neck.- Digital Tuners- Small screwdrivers, extra tuner screws- Utility knifes- Hand saws- Example monochords from last yearMaterials 1 monochord per lab group. I ordered the fret wire, saws, snippers and economy tuners fromStewart McDonald. I am still not sure what the best materials are for the bridge and nuts. Popular seemsto be ¼”x ¼” wood (pickup at hardware or hobby shop) and same in plastic (ordered from Plastruct?).Also slightly smaller squares are good in plastic. The ¾” poplar does bend, affecting the pitch.Warning: use safety glasses when using power tools. Wear protective eyewear when near an operating drill press. If you are drilling and other people are watching the drill, please make sure they too are wearing protective eyewear.INTRODUCTION In this lab we will construct a monochord. We will use the tempered scale to calculate the location to place frets along the neck of the monochord. After we make a working fretted monochord, we will measure the accuracy of our scale. Half notes in the tempered scale have frequency that differ by a factor of21/12 = 1.05946. For a string the fundamental mode frequency is proportional to the inverse of the string length. Figure 1: Our monochord will use one of these economy guitar tuners so that we can adjust the tension on the string. We will mount the tunersPhysics of Music PHY103 Lab Manual 2011perpendicular to their normal orientation so that we do not have to have the headstock (see Figure 2) at a different angle than the guitar neck.Figure 2. Parts of an acoustic guitar.CONSTRUCTION1. Cut a board. Cut a piece of 1 ½ x ¾” (actual size) hard wood to a length of about 2’ 8”. Guitar strings are only 3’ long so your board cannot be longer than that. Please use a hand saw, not a fret saw.The fret saws are a specific width to fit the fret wire and are best used for delicate cutting, not sawing boards in pieces.2. Installing the tunerDrill first a 11/32” and then a 1” hole as shown in Figure 3. Center the 1” hole so it will be centered on thecenter of the tuner. Insert the metal sleeve into the 3/8” hole face that is in the 1” hole edge. Drill 2 verynarrow holes for the 2 tuner screws. Install the tuner. Screw the two holding screws into the tuner.A note on drilling: Remember to put a piece of scrap wood below the piece you are drilling into when youare using the drill press. Otherwise you will wind up drilling into the metal table. Start by drilling a smalland precisely located hole before you drill a large hole. Use safety glasses. Be aware that the wood cancatch on the drill and start spinning. It is good to drill large holes with the drill press. You can start a largehole by drilling a small well positioned hole first.11/32” hole that does not need to go all the way through the boardFigure 3 Showing 2 holes needed to install the tuner shown in Figure 1. The metal sleeve shown in Figure 1 is inserted at the location of the orange ring so that the tuner does not wiggle.Physics of Music PHY103 Lab Manual 2011Washer to keep the string end from digging a hole into the woodRecessed larger hole to hold washer and bead on the end of the string. The recessed larger hole makes it possible for the monochord to lie flush on the table.Figure 4: Two more holes must be drilled so that the end of the string can be held. Physics of Music PHY103 Lab Manual 2011Figure 5 A fretted guitar neck. Notice the frets are closer at the bottom. Physics of Music PHY103 Lab Manual 20113. Fixing the end of the stringFirst drill a hole small enough that the string canpass through the hole (e.g., about 5/64”diameter) but not the round bead at the end ofthe string. Then drill a hole on the backside ofthe board just large and deep enough to hold thewasher (about 7/16”; see Figure 4). The washeris there to spread the weight from the end of thestring out over a larger area. The washer andbead on the end of the string (diameter ~4mm)are sunk into the backside of the monochord sothat the board can lie flush against the table.4. The frets Mark the location where you would like to putthe bridge and measure the distance (L) that thestring will have between the nut and the bridge(see Figure 2). Using the tempered scale calculate the locationof at least 6 frets. The first fret should be at adistance L/21/12 from the bridge, the second fret L/22/12, the third L/23/12 from the bridge, etc….. The frets should be getting closer together as you move away from the tuner. Using the fret saw and miter box, saw narrow groves into the neck at your marked fret locations keeping the saw perpendicular to the neck. Carefully tap or push the fret wire into each grove. Snip off the ends ofthe fret wires so the ends are flush with the board edge. File the edges of the frets so the neck edges are smooth. The fret saw should exactly match the width of the fret wire. Try to saw smoothly. If the saw bends while you are sawing the slot cut will be too wide and the fret wire will tend to fall out of its groove.5. String your monochordThread the string and tighten it. The pitch for your monochord will likely depend on the type of string that you chose.6. The nut and bridgeThe nut is the piece of wood or plastic that raises the strings above the neck on the side of the string opposite the tuner (see Figure 2). The bridge is the piece of wood or plastic that raises the strings above the neck on the side of the string opposite the tuner. I found pretty good luck with ¼” tall wood bridge and 1/8” plastic nut with a groove for the string. You can make the bridge higher than then nut. If the nut is too high it will be hard to press down the strings to the fingerboard. Some adjustment for height