MUSIC
MACHINIST’S PHONOGRAPH
Half-nut
1: 5
ratio
1: 10
ratio
20 TPI lead screw
Carriage
Weight
Rail
5"
4"
Lead screw drives
Motor-driven pulley
MATERIALS
2" aluminum plate, 12"× 6¼"
Aluminum blocks, 4"× 1"×½" ( 4)
½" aluminum rods, 4" long ( 2)
¼"× 20 cap screws ( 10)
¼" steel rods/dowels, 1" long ( 2)
½"× 20 UN threaded rod, 8½" long
2" steel rod, 8½" long
7" steel rod, 9¾" long
2" ID Oilite bushings ( 2) Made out of oil-impregnated bronze, these are self-lubricating.
Nylon rounds and scrap pieces
Rubber drive belts, style U/7 ( 2) for vacuum
cleaner carpet brush
¾"-thick pine board
Wood screws
Grub screws, ¼"× 20 ( 7)
AC fan motor Mine was rated at 1,550rpm.
Fan speed control I used an off-the-shelf wall
control for a ceiling fan.
Wood glue, super glue, filler, stain, and varnish
Tone arm, cartridge, and rubber feet from
an old stereo turntable
Sapphire stylus for 78rpm records
Glass shards to make a glass ball stylus
TOOLS
Vertical milling machine
Small metalworking lathe with compound slide
Tap and die set, ¼"× 20 and ½"× 20 UN I tried
to use as few taps as possible and allow the
machine to be dismantled and assembled with
as few tools as possible.
Table saw or back saw and wood chisels
Drill and 3" reamer
Sandpaper
Gas flame and tweezers to make glass ball stylus
142 Make: Volume 14
and included a knob that adjusts the speed down.
For cylinders of different sizes, I made swappable
mandrels to fit the drive shaft in the 3 standard
diameters plus a longer mandrel to handle the
6"-long Columbia cylinders, along with matching
sleeves that fit around the tone arm stalk to lift it
to the proper height. The lead screw has 6½" of
usable travel, more than enough to handle the job.
The toughest variant was groove pitch. Two-minute cylinders have 100 grooves per inch, and
4-minute cylinders have 200 per inch. To support
both, the belt between the drive shaft and the lead
screw has 2 positions over 2 adjacent pairs of
pulleys, one with a 1: 5 drive ratio and the other with
1: 10. To change the speed, you move the rubber
belt from one pair to the other. The belt material is
sufficiently stretchable that I didn’t need additional
tensioner pulleys, and the tone arm tracks the
