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George Risk Industries switches

Contents

Overview

George Risk Industries (GRI) produce reed keyboard switches in-house. They also re-sold Far East–made keyboard switches under their own series names. Confirmation of the latter came from an anonymous ex-employee, who had mentioned that they purchased switches from “Asia”. The Far East–made types are no longer advertised for sale, presumably because they are no longer manufactured by the suppliers.

Most of the Far East switches were sourced from Futaba; these are the KBR reed type and the KBM and KBM-LP mechanical types. KBM-DIN however appears to be Mitsumi KLT series. While Futaba’s first generation switches were universally unbranded (with branding added only to the later MA series), Mitsumi’s switches were all branded, so it remains to be seen whether KBM-DIN was branded. Some KBM switches were however sold with GRI branding in a custom colour scheme.

Series KB

Series KB comprises tall, cylindral reed switches (1.75″ from base to keycap centre), secured with a nut onto a threaded leg. They support double-pole and normally closed configurations and lamp illumination; the rated lifetime is 50 million cycles.

Series KBPS

This is similar to KB, but designed to be attached to a front panel with a nut above and below the panel. The operating force codes within the part number generally denote higher forces than they do for KB series:

Code Force (KB) Force (KBPS)
01 2.5 oz (71 gf)
02 4.0 oz (113 gf) 5.0 oz (142 gf)
03 6.0 oz (170 gf) 8.0 oz (227 gf)
04 — 15.0 oz (425 gf)

These codes are not mnemonic, as they are with Micro Switch series.

Series KBLP

Series KBLP reed switchces are lower in profile (1.375″ from base to keycap centre) and square in section, but remain secured with a nut onto a threaded leg. The lifetime remains 50 million.

Series KBR

These are Futaba-made reed switches. There is only one known model, which is single-pole momentary non-illuminated with a lifetime of 30 million cycles. The GRI site did not list these in 1998, the oldest archived copy in the Wayback Machine.

US patent 4041427, issued to Futaba in 1977 and filed in 1975, appears to be for these switches, although curiously they are shown with a square-section shell instead of a truncated cylindrical shell. The patent also depicts straight-mount switches, while GRI KBR is cruciform mount. George Risk were able to retrieve the Futaba part number.

Model Type Futaba part
KBR-01-01-B Momentary MR-6C-CM

Series KBM

KBM comprises Futaba-made mechanical switches (Futaba MD series), available in single pole momentary and alternate action forms. The rated lifetime is 10 million cycles.

Series KBM-LP

These are Futaba-made low-profile mechanical switch (Futaba ML series), available in single pole momentary forms only. The rated lifetime is 3 million cycles. It remains unclear whether illuminated forms existed in Futaba ML and sealed linear series. Where GRI needed KBM-LP illuminated keys, they simply snapped or sawed off a corner of the switch to make room for the LED.

Only one part number is known, KBM-LP. This is cited as 0.045±0.01″ pretravel, but a total travel of only 0.01±0.02″. George Risk were able to retrieve the Futaba part number, ML88-CM.

Series KBM-DIN

These are Mitsumi made; George Risk report them to be cruciform mount with a white plunger. They are likely KLT series as they are stated in the catalogue as being tactile. These were also not listed for sale in 1998; there is no record of these ever being sold separately.

The specifications are given as follows for Model 3075 keyboard and Model 3032 keypad:

Parameter US Metric equiv.
Total travel 0.157±0.020″ 3.99±0.51 mm
Pretravel 0.100±0.005″ 2.54±0.13 mm
Operating force 1.23±0.35 oz 34.9±9.9 gf

Documentation