Editing Stabiliser

{{TODO photo|more=true|reason=need photo of plate-mounted Cherry stabilisers}}
[[File:Stabilised keycaps.jpg|thumb|250px|right|Wire-stabilised keycaps]]
[[File:Stabilised scissor switch.jpg|thumb|250px|right|Stabilised [[scissor switch]]]]

A '''stabiliser''' or '''stabilizer''' (abbreviated to '''stab'''; also '''levelling mechanism''' in [[Cherry]]'s terminology) is a device intended to stabilize a large keyboard key.

==Concept==
Stabilisers have two purposes:

*They prevent [[binding]] by helping to ensure that the keycap motion is vertical and that the keycap remains level no matter whereabouts it is pressed
*They prevent the play inherent in the switch slider from leading to significant wobble or tilting in larger keys, in particular space

Stabilisation is frequently applied to keys of 1.75 [[unit]]s width and greater. On a typical full-size US keyboard, this includes left and right shift, enter, backspace, and the plus, zero and enter keys on the numeric keypad.

The hardest key to stabilise is a [[enter key|big-ass enter]] key, and it's not unusual to have parts of this key be very difficult to press. The [[Zenith Supersport SX]] enter key has a complex stabiliser arrangement that is extremely difficult to assemble, but provides flawless transfer of force to the switch from anywhere across the keycap.

The [[scissor switch]] is actually a (typically plastic) stabilizer designed for all keys, not just large keys, on a low-profile keyboard, typically using [[rubber dome]] switches. Larger scissor switches can still be given extra stabilisation.

==Design==
Many stabiliser designs have been used over the years. The common varieties are as follows:

===Wire===
The most common design is the wire stabiliser. A stiff wire runs from one end of the key to the other, connected to the keycap at each end, and to the keyboard plate or PCB via some form of restraint. The wire pivots against both the keyboard and keycap; pressing one end of the key rotates the wire, and the other end of the wire pulls its end of the keycap down accordingly. More than simply keeping the keycap moving vertically (important to prevent [[binding]]), this method actively keeps the keycap level.

This forms the basis of the stabiliser designs used by Costar, Cherry, SMK, and some of those from Alps and IBM.

The compound stabiliser design used in the [[Zenith Supersport SX]] for the enter key (shown below) is subject to Alps patent [https://www.google.com/patents/US4771146 US 4771146], filed in 1987 and with a priority date of 1985.

<gallery widths=250 heights=187>
File:Stabilised key.jpg                                            | Wire-stabilised key
File:NTC 6752-EA -- caps removed.jpg                               | [[NTC KB-6752EA]] internals, showing stabiliser wires
File:Zenith Supersport SX -- Enter key stabiliser.jpg              | Zenith Supersport SX enter stabiliser, Alps-patented
File:Zenith Supersport SX -- Enter key stabiliser disassembled.jpg | Zenith Supersport SX enter stabiliser disassembled
</gallery>

===Dummy switch===
This design pairs a normal switch with a dummy switch. This approach has been used by Micro Switch for their Hall effect keyboards, as well as in [[ITW magnetic valve]] keyboards.

In the case of the ITW design, the stabiliser dummy switch feels quite light and seems to have low [[preload]].

===Guide shaft===
Some manufacturers such as Alps and Fujitsu used guide shafts for some or all large keys. A plastic insert is fitted, bearing a guide shaft, and a plastic post within the keycap fits into this shaft. This approach is not always successful; the Fujitsu FKB4700 is infamous for the poor quality of its stabilisation. However, this approach works well in IBM Model M keyboards.

<gallery widths=250 heights=187>
File:Apple M0118 Return.jpg                                        | [[Apple M0118]] return key, with guide shaft stabiliser
File:Fujitsu FKB4700-152 -- supernumerary traces and domes.jpg     | [[Fujitsu FKB4700]] enter key switch and guide shaft insert
</gallery>

===Dual switch===
The SMK-made "Type 2" keyboard for the [[Acorn BBC Microcomputer]] has been found with a pair of light weight switches under the return key. [[Matrix layout]] [[POS]] keyboards allow keycaps to span multiple switches in 1×2, 2×1 and 2×2 arrangements; here, the keys will be substantially heavier as a result.

==Implementations==
===IBM===
IBM originally used wire stabilisers in the Model M keyboard, but changed to barrel inserts at the end of the 1980s.

<gallery widths=250 heights=187>
File:IBM Model M -- late 1G numpad stabiliser.jpg                  | Early [[IBM Enhanced Keyboard|Model M]] stabiliser
File:IBM Model M - stabiliser.jpg                                  | Later Model M stabiliser
</gallery>

===Cherry===
====Cherry MX====
[[Cherry MX]] ''levelling mechanisms'' are intricate assemblies with keystems that allow for extremely easy removal and replacement of keycaps. The [[Cherry]] design also greatly reduces the noise associated with stabilisers. The chief complaint is that they dampen the switch feel, giving stabilised keys a stiffer and mushier feel. A small modification to the design—clipping a small piece off the sliders—does rectify this issue.<ref>Deskthority — [http://deskthority.net/workshop-f7/cherry-corp-stabilizers-gimme-back-my-clack-ok-whaaat-t2780.html Cherry Corp Stabilizers, GIMME BACK MY CLACK! "Ok." WHAAAT?!]</ref>

=====PCB mount=====
PCB-mount Cherry MX levelling mechanisms clip into the PCB. The PCB contains four holes, two per side; the rear stabiliser legs allow it to be swung into place via the rear holes, and prongs in the front place grip the front holes. The whole assembly can be inserted and removed easily.

<gallery widths=250 heights=187>
File:Cherry G80-3000 -- right shift with levelling mechanism.jpg   | Cherry levelling mechanism in a [[Cherry G80-3000]]
File:G80_3000WIN_aspacebar.jpg                                     | 6.25 units [[space bar]] with mounts for [[Cherry]] and [[Filco]]. Below are the [[Cherry G80-3000]] stabilisers.
File:Cherry MX levelling mechanism -- PCB mount.jpg                | Levelling mechanism from a [[Cherry G80-3700]]
File:Cherry MX levelling mechanism -- PCB mount, mounted.jpg       | [[Cherry G80-3700]] levelling mechanism mounted into PCB; one of the rear legs is not correctly inserted
File:Cherry MX levelling mechanism -- PCB mount, top.jpg           | Top
File:Cherry MX levelling mechanism -- PCB mount, front.jpg         | Front
File:Cherry MX levelling mechanism -- PCB mount, bottom.jpg        | Bottom
File:Cherry MX levelling mechanism -- PCB mount, disassembled.jpg  | Disassembled
</gallery>

====Cherry ML====
[[Cherry ML]] keyboards use simple wire stabilisers.

<gallery widths=250 heights=187>
File:Cherry G84-4400 -- stabiliser.jpg                             | Basic Cherry ML stabiliser
File:Cherry G84-4400 -- space bar.jpg                              | Cherry ML stabiliser for space bar
File:Cherry G84-4135PTMDE -- stabilised keycap.jpg                 | Stabilised keycap with wire and PCB clips
File:Cherry G84-4135PTMDE -- stabiliser clip removed.jpg           | Stabiliser clip removed from the PCB
</gallery>

===Costar===
Keyboards from [[Costar]] use simple wire stabilisers. Possibly as a result of the widespread adoption of Costar-made keyboards, all simple wire stabilisers get referred to as "Costar stabilisers".

====Filco-style====

<gallery widths=250 heights=187>
File:Filco Majestouch 1 -- Costar stabiliser.jpg                   | Genuine Costar stabiliser in a [[Filco Majestouch]]
</gallery>

====Non-Filco-style====

<gallery widths=193 heights=240>
File:S54s6zv.jpg                  | Non-Filco-style stabiliser in a [https://deskthority.net/workshop-f7/the-long-journey-of-the-whitefox-t12134.html Whitefox]
FIle:Non-filco-style-stabilizers.jpg | Non-Filco-style stabilizers tried on a Filco (the keys can't be fully pressed)
</gallery>

The wires on these stabilisers bends outward—similar to the stabilisers provided with the WhiteFox and KC60—instead of perpendicular to the plate. [http://www.switchtop.com/product/costar-stabilizers-and-keycap-inserts]

===NMB===
<gallery widths=250 heights=187>
File:Dell RT7D50 -- plastic stabiliser assembly 3.jpg              | [[NMB]] plastic stabiliser bar assembly in a [[Dell RT7D50]]
File:Dell RT7D50 -- plastic stabiliser assembly 1.jpg              | NMB plastic stabiliser bar in place
File:Dell RT7D50 -- plastic stabiliser bar.jpg                     | NMB plastic stabiliser bar and keycap
</gallery>

===Topre===
<gallery widths=250 heights=187>
File:Topre Stabiliser - Spacebar - Top.JPG                         | Topre stabiliser for the space bar key; note that the ends of the metal wire can be seen on the left and right.
File:Topre Stabiliser - Spacebar - Bottom.JPG                      | Stabiliser mounts for the space bar of a Topre keyboard, as seen from the bottom with case and PCB removed. 
File:Topre Stabiliser - Small - Bottom.JPG                         | Topre stabiliser for a function key on a [[Sony BKE-2011]] as seen from the bottom of the keyboard with case and PCB removed.
</gallery>

===ITW===
Second-generation [[ITW magnetic valve]] keyboards used dummy switches for stabilisation. These switches lacked the ferrite core and magnet of live switches, and had a circular rather than square keycap mount.

<gallery widths=250 heights=187>
File:ITW magnetic valve G2 stabiliser -- top.jpg    | Dummy switch, used as a stabiliser
File:ITW magnetic valve G2 stabiliser -- opened.jpg | Dummy switch opened; note the lack of magnet and ferrite core
</gallery>

===Clare/Pendar===
In [https://www.google.co.uk/patents/US3771636 US patent 3771636] (filed April 1971), [[Clare Pendar]] describe a mechanism where a pair of interlocked arms are placed below the PCB/plate, attached to the space bar.

===SMK===
[[SMK J-M0404 series]] uses slider lubrication to reduce binding on wider keys that do not have wire stabilisers. Apple describe these as "low friction" types.

<gallery widths=250 heights=187>
File:SMK J-M0404 slider comparison.jpg | Standard and low-friction J-M0404 series sliders
</gallery>

==Inserts==
Inserts are small plastic parts that connect the stabiliser wire to the keycap.

<gallery widths=250 heights=187>
File:Tulip ATK 030244 stabiliser inserts.jpg                       | [[Keycap mount#Cherry MX mount|Cherry MX mount]] inserts for an [[Keycap mount#Alps mount|Alps mount]] [[keycap]] ([[Tulip ATK 030244]]); mount aside, this insert style is one of the most common
File:Stabiliser -- SMK.jpg                                         | [[SMK]] stabiliser, [[Tulip SMK series]]/[[Sony PCY-333]]; the inserts hold the wire against the inside of the keycap
File:Tulip ATK 03.01.44 -- stabiliser components.jpg               | SMK stabiliser components
File:Tulip ATK 03.01.44 -- stabiliser post.jpg                     | Miniature cruciform insert post
File:Tulip ATK 03.01.44 -- spacebar stabiliser.jpg                 | SMK stabilisers place the sliding action at the plate, instead of within the keycap insert; the plate insert also contains guide shafts to support guide posts in long keys (i.e. spacebar)
File:Filco Majestouch 1 -- Costar stabiliser inserts.jpg           | Costar stabiliser inserts from a [[Filco Majestouch]] 1
</gallery>

==References==
<references />

[[Category:Keyboard terms]]