After you send Wesley Wolfe your music, he opens it in ProTools for frequency analysis. The vibrations of certain high-end frequencies can upset the cutter-head of the lathe, while very low frequencies can make the record's groove so deep it collapses on itself and pops out the cutting stylus. For this reason, many hand-lathers, including Wolfe, are reluctant to cut harsh noise or other kinds of music where extreme frequencies are indispensible. After making the necessary adjustments to ensure that he doesn't snap the $300 industrial diamond stylus manufactured only by Souri in Germany, Wolfe converts the music into a wav file, burns it on a CD and takes it over to the main unit.
THE MAIN UNIT
The main unit is a cobbled-together rack of audio equipment next to the lathe. It isn't actually called the "main unit," either. Because Souri's lathe is custom-made, the names of its parts are all either generic and technical or practical and informal. Wolfe puts the burned CD into the unit and begins to play it back. He toggles a switch to determine how many songs will be cut to each side of the record. He adjusts the master volume until he finds the peaking level, probably around 3 decibels. This tells him how wide to set the grooves of the record. More distance between grooves makes a record louder but reduces its playing time. Wolfe's 7-inches can hold about seven minutes per side at most, and that's at 33 1/3 rpm. That makes them quiet and low on bass, so he generally cuts only four minutes per side.
The lathe itself looks like a tricked-out record player. Basically, it is. Wolfe turns a carriage, like on a typewriter, to clear the cutter-head away from the turntable. Exposing the black vinyl blank, he lays it on the platter where it immediately starts to revolve. He positions the cutter-head at the outer edge of the record and lowers it. The needle bites into the blank and starts to cut. The cutter-head houses a pair of magnets, left and right for stereo, like an electric guitar pickup. They transmit the vibrations of the music through the diamond-tipped stylus, preserving every frequency and timbre in the shape of the groove. An arm with a regular record-player stylus provides simultaneous playback, monitoring the fresh-cut groove.
Once the volume and groove width are set, Wolfe pulls a vinyl blank in a protective white film from a rack below the lathe. The manufacture of these sought-after "virgin vinyls" is another Souri exclusive. No one else is known to use this particular polyvinyl chloride, which has a surface-noise level competitive with pressed records when cut directly.
The vinyl carved out by the needle, known as "chip" or "swarf," is simultaneously vacuum-pumped away from the record itself. "That's the music!" Wolfe exclaims, beaming and pointing at the canister of chip like a parent at a sonogram. After having tested and cleaned the new record, Wolfe peels a label from a die-cut sheet and affixes it around the spindle hole. He prints out the art, folds it into a sleeve, slips the new record inside, and repeats the process until the order is filled.