Cocobolo boom modelo

THE LATHE, aka: LS-76, and the LJ-10 and LJ-12 tape machines
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Cocobolo boom modelo

Post by Fonotec » 04 Sep 2015, 19:01

THE LATHE normally shipped with a video camera-equipped microscope, having a swiveling boom stand which allows the microscope (and camera, mounted on top) to be positioned over the platter for examination of the groove across the workpiece. One needs to confirm the groove width and also the packing of spirals (to ensure no overcuts or lift-outs occurred).

#660 arrived in Cincinnati without a few items, including a tone arm and the microscope boom stand, as well as the wooden curtains that conceal the card cage, underneath the steel weldment.

A while ago, I found a Stax 12" tone arm (with Stanton cartridge, using a Superheterodyne stylus ) on ebay (See thread entitled. Stand off block, for details). Recently, I was able to make a modelo for a new microscope boom stand for #660. I had already secured a vintage Leitz Wetzlar monocular microscope with diffusor attachment for lightfield microscopy.

The modelo is made from a couple of 18" long pieces of 1_1/2" x 1_1/2" Cocobolo. It's a rather aromatic wood that smells like Cade when it's drilled or sawn. I cut two lengths from the long bars (one, 7_1/2" and the other, 10"). Then, using a vintage Chicago Tools bench drill press, I hogged out the bottom of the shorter piece so as to put a needle bearing (from VXB) inside, having an inner diameter of 7/8", which allows the bearing to straddle a 7/8" diameter dowel pin which is partially inserted into the microscope boom stand chuck in the lathe's aluminum table.

This microscope has two vintage Leitz objectives that magnify by approximately 75x and 150x.
Cocobolo_boom_modelo.JPG (163.41 KiB) Viewed 593 times
I tested the swivel motion, which is very smooth, thanks to the pin bearing, and confirmed that I could focus on a record's grooves while it is revolving. I used a pressing of Zapp's "More Bounce to the Ounce" (produced by Bootsy and cut at Allen Zentz Masteing, in Hollywood) for the test.
Scans_playing_grooves.JPG (144.49 KiB) Viewed 593 times

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