HISTORY:
Ex USA made test equipment, actually there is a story behind this knob. The equipment I was examining (KEITHLEY 642 ELECTROMETER) is from the 1980's ~ 1990's era but someone had made a minor modification and they used THIS knob for the rotary potentiometer that had been installed.
This knob is NOT from the same era as the equipment, I would estimate it to be from the 1950's ~ 1960's based on both the design and the fact it is constructed from Bakelite (a type of early plastic)
UNKNOWN MANUFACTURER - Panel Knob
"Probably" made in USA (based on the fact that all other components in the original instrument are USA sourced parts and it seems most likely the user just grabbed a local "spare" knob they had to hand when making their modification to the 642)
Material: Bakelite (Dark Brown) body
Brass insert for the shaft fitting, a single grub screw (slot head) is used to secure this knob to the shaft
Round knob with "scalloped" edges, looking something like a flower shape! Nice finger gripping design ...
NO marker(s) of any kind
DIMENSIONS:
Top "flower" section 23.75mm x 6.55mm height
Lower section: 20.5mm diameter x 9mm height
Centre hole (Brass bushing fitted) suits a standard 1/4" shaft
Single side entry grub screw (included)
COSMETIC CONDITION:
USED
CLEAN
Beautiful condition quite frankly! After all these years, no chips, no cracking and no surface markings
BAKELITE testing:
If you know Bakelite products, they "jump out at you", they feel and look different to modern plastics. But a "hunch" isn't good enough so I made the usual tests to establish for sure that this material is Bakelite based.
When dropped, it sounds like Bakelite (yes, Bakelite has a "different" sound) (tick)
It "feels" like Bakelite (tick)
Rubbed the surface vigourously and Ah! yes, don't you love that sweet smell of formaldehyde in the morning! (tick)
Next I rubbed a small spot with a white cotton bud dipped in a polishing solution and yes siree! the distinctive Yellow/Brown colouring is left on the cotton bud (tick)
100% this is Bakelite
Since I have finished with this knob, it has been sealed in a clear plastic packet and will be supplied this way
