Here is an contribution from sweden. First we will again say how much we enjoy to receive the list.
In list 266 was a question on bakelite.
My father(age 80) has a very long experience due to machining bakelite.
Also to make eyecups to his binocular-collection (aprox. 180 pcs) when he find binoculars without eyecups on fleamarkets.
(a good arguement for hoggling the price)
Bakelite can be ordered from specialized dealers.
The most important is to use sharp tools. Then its possible to make clean threads and get a nice surface.
The speed depends on the diameter of the material, but at 1 and 3/8 inch of diameter on the eyecup, a speed of 450 r/m is preferable , when forming the eyecup. This moment is quite simple to do.
Then comes the more sofisticated part, when to make the threading. You have to decrease the speed of the machine due to its small numer of threads to do (3-10?) If you don´t reduce the speed you destroy the cup in fragments of seconds.
When the thread is ready the eyecup bakelite has to be polished with very fine steelwool (000).
Now the result is a dark grey or brown eyecup which is quite ugly.
The final moment is when you are satisfied with the surface and smoothening but not the color. Now you take a little oil on a cotton cloth and polish it up to dark black.
The eyecup is ready.
Attention!!. Before you use all types of rotating machines you must be avare of the high risks to get accidents and get loose of your eyes or fingers etc.
Our advise is to first get contact with an experienced craftman or perhaps a craftschool to show you if you are unsure.
rgds Björn and Sven-Olof Nyman Sweden
Subject: Bakelite etc.
Are you after total originality? Phenolic WW II were mostly/all molded, I believe. It does not machine well. Black Delrin does. Bore the treads inside as deeply as the biggest fitting boring bar will go. Damp incipient vibrations with your hand, etc. Keep it cool with water soluble fluid. Then use a form tool and/or files to round the external edge. Use kitchen scrubber in water to blend curve by hand. Cut off eyecup. Repeat, until you run out of the bored internal thread. Sell the extras.
A thread-less design for drill press only is: Cut plate of appropriate thickness into octagons or more-sided-agons. Central drill to match screw in a little cylindrical workholder with an axial tapped hole. Chuck assembly. File to diameter desired, and then round one side of the periphery (top or bottom) with file, abrasive loaded kitchen scrubber, etc. De-mount. Hold in vise with rubber pads at edges to increase friction. Drill (or bore) to fit over male threads on eyepiece. Drill and tap one to three radial holes for nylon setscrews . Voila.
Subject: Catalogs, manuals, etc.
Deutsche Optik has a new (?) reprint listed on p28 of their printed catalog.
Navships 250-624-2, Manual for Overhaul, Repair, and Handling of 7 x 50 Binoculars with Parts Catalog. 1951.