Mechanical Keyboard Guide

Fact: Nearly all keyboards sold bundled with computers or at retail stores use rubber domes under their keys. This is the same technology used in cheap TV remotes. They're made to be as cheap as possible to manufacture in order to maximize profits. Yes, this even includes "high end" keyboards. So why settle for something that is made as cheap as possible?

So Why do YOU want a Mechanical Keyboard?
For most people it's all about the feel. With the keyboard you're typing on right now you've got to press the key all the way down to the bottom to get it to register. This wastes a lot of energy and causes fatigue, as most of your effort is spent pushing against a solid piece of plastic. Mechanical keyswitches are designed so that they register before you bottom out, so you only need to apply as much force as is necessary to actuate it, not wasting any. And with as many different types of switches as there are you can pick and choose which one you're the most comfortable with, as each one has a different feel to it. And most people who try one can never go back to using rubber domes, as they realize just how "mushy" they really feel.


Index:

• Page 1: Terminology
• Page 2: Common Switch Types
• Page 3: Keycap Plastic & Shape
• Page 4: Keycap Printing
• Page 5: Modern Mechanical Keyboards
• Page 6: [Incomplete] List of Keyboards by Switch Type
• Page 7: Replacement Keycaps & Maintenance
• Page 8: Miscellaneous Information & Resources
• Page 9: Credits & Thanks

Terminology

Key Blocking & Ghosting
Ghosting is when you press two keys on the keyboard, and a 3rd key - which you didn't press - gets sent to the PC as well. This is very rarely seen on even the cheapest modern boards, because manufacturers have the habit of limiting the rollover so that ghost keys are always blocked.

Key Blocking is as simple as it sounds; you experiencing it when you reach your maximum key roll over. So if you press 2 keys, and the third key is blocked on your board; then you just experienced blocking because your keyboard is only 2KRO.

Key Rollover (#KRO & NKRO)
NKRO is when you can press as many keys as you want at the same time, and all of them go through. This is similar to what some 'gaming keyboards' incorrectly market as "anti-ghosting", even though Logitech and Razer only apply it to the WASD cluster. Note that right now only PS/2 keyboards can exhibit full n-key rollover; though Microsoft and Ducky are just two companies who have already looked at designing NKRO over USB.

#KRO, where # = Any Number, is the key roll over of your board; and stands for the maximum number of keys you can press without experiencing any key blocking.

Many USB mechanical Keyboards are labeled as 6KRO, meaning any 6 keys can be pressed at once without the user experiencing blocking. This is generally enough for most users. Though a limited number of games may have a problem with 6KRO.
USB keyboards with 6KRO also allow for a maximum of 4 modifier keys to be used with those 6 normal keys. These modifiers include CTRL, ALT, Shift, & Super (Windows, Command, or Meta Key.)
Sometimes this also includes the FN key present on select keyboards.

Key Bouncing
All types of key switches - including rubber domes - do this. When you press a key, the switch "bounces" on and off very quickly as it sets into place. This causes keys to register multiple times for each press. Because of this, keyboards need to implement some sort of debouncing delay - so that once you press a key, the controller waits a certain amount of time before registering a keypress. As an example, Cherry MX switches need 5ms of debouncing time, while rubber domes need longer (exactly how long depends on their quality).

Polling Rates and Response Times
While it is very useful for mice, it's just about meaningless for keyboards. Let's assume for a minute that all switches have the 5ms debouncing time of Cherry MX switches (which is being very generous). Even if you had super human speed and reflexes, every single key would be delayed by at least that much. So really, any polling rate over 200Hz (at best) is absolutely useless, and nothing but market hype. It may even be a bit detrimental, because you'd be wasting CPU time polling the keyboard unneededly. And unlike USB keyboards, PS/2 boards aren't polled at all. They simply send the signal to the PC whenever they are ready to, which causes a hardware interrupt, forcing the CPU to register that keystroke.

PS/2 or USB?
PS/2 wins on three fronts: First, it supports full n-key rollover. Second, PS/2 keyboards aren't polled, but are completely interrupt based. And third, it is impossible for it to be delayed by the USB bus being used by other devices. There are two types of USB transfer modes - the interrupt transfer mode (USB polls keyboard, when key is sensed the USB controller sends the interrupt to the CPU), and the isochronous transfer mode, which reserves a certain amount of bandwidth for the keyboard with a guaranteed latency on the bus. Unfortunately, there are absolutely no keyboards made that use the latter, because special controllers would have to be used, thus making it cost prohibitive.

So if your keyboard supports both PS/2 and USB, and your PC has a PS/2 port, there's no reason not to use it.
Edited by Manyak - 2/15/11 at 8:09pm

Common Key Switches

Introduction - A Switch is Not "Just a Switch"

Many people ask for recommendations about switches without knowing exactly what they are looking for, but instead only with an idea of what their needs are. Fortunately, this is not always a problem because most mechanical switches will always feel nicer than rubber domes. However, the final choice is very important because a switch is not just a switch; it is the heart of what makes your keyboard have its feel and your personal tastes can make or break a keyboard for your uses. If you don't like the switch when you type on it, most likely, you won't ever like the keyboard.

Switches are generally rated by force using the weight measurement of Grams (g). Although force is more accurately described using Centinewtons (cN) However, 1g of weight applies about 1cN of downward force, so we can use "55g" when describing a 55cN-rated switch because that is sometimes easier to understand. For this fact; we'll use Grams as a measurement of force; though either term is correct.
For perspective, it would be wise to remember that your average rubber dome keyboard requires between 55g and 60g of force to actuate.


Cherry MX Black Switches

Type: Linear Switch
Link: Datasheet
Tactile: No
Clicky: No
Actuation Force: 60g (40g-80g overall) (Force Diagram)
Key Travel: 2mm to actuation, 4mm to bottom

Cherry MX-Black switches are linear (non-tactile) switches, these are considered one of the best switch types for gaming. When gaming, having a tactile bump does absolutely nothing because you're going to be bottoming out anyway. So these give you a very smooth feel. The actuation and release points are at the exact same position as well. So games that require a lot of double tapping become easier than on any other keyswitch. However, most people don't enjoy typing on them that much do in part, to their linear nature.
If you're a person who tends to hit a wrong key every so often while gaming, these will be beneficial in that the high actuation force will help prevent many of those accidental presses.

Cherry MX Brown Switches

Type: Tactile Switch
Link: Datasheet
Tactile: Yes
Clicky: No
Actuation Force: 45g (55g Peak Force) (Force Diagram)
Key Travel: 2mm to actuation, 4mm to bottom

Cherry MX Brown switches are considered a middle ground between typing and "gaming" switches. They have a light, tactile feel half way through the key press that lets you know the switch has activated. This gives you an indication of what you can release the switch. The switch is considered a middle ground because the reset point & actuation point are close enough together than you can "float" at that point, enabling you to double tap faster.

As a note: this switch actually has a peak force of 55G, it is 45G at the point of actuation. This is due to the design of the Cherry switch itself.

Cherry MX Blue Switches

Type: Tactile & Clicky Switch
Link: Datasheet
Tactile: Yes, precise
Clicky: Yes
Actuation Force: 50g (60g Peak Force) (Force Diagram)
Key Travel: 2mm to actuation, 4mm to bottom

Cherry MX Blue switches are the best cherry switch for typing. The tactile bump can easily be felt, and the resistance is similar to your average keyboard.

Although many people find them just fine for gaming, some don't like the fact that the release point is above the actuation point. This can cause some trouble with double-tapping. This is usually the case with someone who has experienced other mechanical switches before hand.

As a note: this switch actually has a peak force of 60g, it is 50g at the point of actuation. This is due to the design of the Cherry switch itself.

Cherry MX Clear Switches

Type: Tactile Switch
Link: Datasheet
Tactile: Yes
Clicky: No
Actuation Force: 55g (65G peak force) (Force Diagram)
Key Travel: 2mm to actuation, 4mm to bottom

Cherry MX Clear switches have often been called "stiffer browns" though some users note that they have more of a tactile feel than browns do. This really can be a subjective topic, though this is another switch that could be considered "ballanced." The force required is comparable to most rubber dome keyboards, with a nice tactile feedback to tell you the key has actuated. These switches are harder to find on keyboards.

As a note: this switch actually has a peak force of 65g, it is 55g at the point of actuation. This is due to the design of the Cherry switch itself.

Cherry MX Red Switches

Type: Linear Switch
Link: Datasheet
Tactile: No
Clicky: No
Actuation Force: 45g (Force Diagram)
Key Travel: 2mm to actuation, 4mm to bottom

Cherry MX-Red's are another switch that can be considered a "gaming" switch. It's essentially a lighter version of the MX Black, requiring less force to actuate. Some people do not find this switch that good for typing or gaming because it is so light, but others rave for this fact. Light or Stiff is always a matter of preference. This switch was hard to find; and was reported as EOL, but it is still in limited production with a higher than average MOQ leading to higher cost to board makers. Marketed with high demand, boards with this switch are becoming more common, but are generally more expensive as well.

Buckling Spring Keyswitches:

Type: Tactile & Clicky Mechanical Switch
Link: Patent
Tactile: Yes, very precise
Clicky: Yes, loud
Actuation Force: 65g-70g (Force Diagram)
Key Travel: 2.3mm to actuation, 3.7mm to bottom

Buckling springs are pretty straightforward once you see them in action. After pushing the key down a certain distance the spring buckles under pressure, causing the hammer at the bottom to hit a membrane sheet and create an electrical contact. The buckling of the spring also provides tactile feedback and a satisfying click as it hits the shaft wall. And you might also notice through the force diagrams that this is the only mechanical switch where the tactile and audible feedback correspond to the exact moment the switch actuates.

Black Alps

Type: Tactile Mechanical Switch
Tactile: Yes
Clicky: No
Actuation Force: Simplified 60g, Complicated 70g (Force Diagram)
Key Travel: 3.5mm

Black Alps are one of the two most common Alps switch types. Many people do not like these switches due to the fact that they are stiff, bottom out hard, and tend to develop friction in the travel as they wear. Nonetheless, they are an improvement over most rubber dome keyboards.

There are two different types of Black Alps switch - an older type known as the "Complicated" due to the large number of parts in the switch, and a newer type known as the "Simplified", which was manufactured by Alps and some other companies. Complicated switches are common in many older keyboards, particularly the Dell AT101W, which is a very common mechanical keyboard from the 1990s.

The most well known Simplified Black switch is made by a company called Fukka, and was used in the ABS M1. The Fukka switch has less resistance, but many claim that it provides less solid tactility than the complicated switch.

White Alps

Type: Clicky & Tactile Mechanical Switche
Tactile: Yes
Clicky: Yes
Actuation Force: 60g-70g (Force Diagram)
Key Travel: 3.5mm

White Alps are one of the most common Alps switch types. These are far more popular than the Black switches due to more pronounced tactility, and the lower force requirements of some versions. Like the Black Alps, White Alps are much easier to bottom out on compared with other mechanical keyswitch designs.

As with the Black switch. there are Complicated and Simplified White switches. The two most popular Simplified White switches are the Fukka and the XM. The XM is almost universally considered to be a terrible switch, it was used on some older Filco Zero models, and some vintage keyboards. The Fukka switch is quite popular, and some people prefer them over the Complicated switch. It is used on some current production Alps keyboards such as current production Filco Zeros, Matias keyboards and some others. Complicated White switches were used on some well made keyboards from the 90s such as the Northgate and Focus keyboards.

There are also a variety of White Alps-like switches of varying quality. Some, like the SMK Monterey, are considered very pleasant to type on..

Topre Key Switches:
(larger image)
Type: Tactile Capacitive Switch
Link: Patent
Tactile: Yes
Clicky: No
Actuation Force: 30g, 35g, 45g, 55g depending on model (Force Diagram)
Key Travel: 4mm

Topre switches are somewhat of a hybrid switch, and are capacitive by nature. The Topre mechanism uses a spring underneath a rubber dome, and the depression of the spring causes a change in capacitance between the underlying capacitor pads. With this change in capacitance; the switch activates.

Topre Switches are considered some of the finest switches available, as they offer a very enjoyable typing experience with a quieter experience compared to a Cherry MX, Alps, or Buckling Spring switch. The reason is Topre switches have the smoothest force gradient even compared to Linear switches like MX-Reds and MX-Blacks.

Edited by Manyak - 12/18/10 at 9:37am

Keycap Plastics & Design

Keycap Plastics:

The two most common keycap plastics are ABS and PBT plastics. Each has their own price to performance ratio; though in a general sense, PBT Key Caps are generally a better buy. We'll go over why:

PBT Plastic (Polybutylene Terephthalate)

• Can Survive up to 150*C (or more in some cases)
• Resistant to solvents
• Mechanically Strong
• Does not "shine" as fast
• Expensive

ABS Plastic (Acrylonitrile Butadiene Styrene)

• Solvents will "melt" the keys
• Keys develope "shine" faster
• Low Cost
• Light Weight

Keytop Shapes:

Cylindrical - Almost all keyboards today use this shape. This is often referred to as sculpted design. The shape is meant to cradle the finger tip.



Flat - Frequently found on laptops and "laptop style" keyboards. These are also found on PointOfSale (POS) keyboards because of the replaceable legends.



Spherical - This shape is normally found on vintage keyboards and type writers

Keycap Printing Methods

Pad Printing
This is the type of printing you'll find on 99% of keyboards. It is the cheapest method possible, short of leaving the keys blank. Pad Printed letters are kind of like stickers, or decals, and you can feel the letter raised above the key surface.

Example: (Microsoft Ergo Keyboard)



Pros:

• Low Cost
• Can print multiple colors on a single key
• Can be used on any face of the key

Cons:

• You can feel the lettering
• Wears out quickly

Laser Etching
Laser etched keys are...well...the name says it all. They feel a bit scratchy. The process works best on light colored keys because the letter always comes out black, since that's the color of burnt plastic. So when it's used on black keys, a paint filler is poured into it, as is done with the keyboards like the Das Model S

Example: (Dell AT101W)



Pros:

• Doesn't wear out easily

Cons:

• You can feel the lettering
• Blurry

Dye Sublimation
Dye Sublimation produces much nicer keys than either of the other two printing methods. A dye is set into the plastic, and seeps a tiny bit into it. So even as the plastic starts to wear off from use, the letter remains as good as new. Unfortunately, because of its cost, the only companies left that use it are Topre, Cherry Corp, and Unicomp.

Example:



Pros:

• Doesn't wear out
• Can't feel the lettering
• Can print multiple colors on a single key
• Can be used on any face of the key
• High Visibility

Cons:

• High Cost
• Can only print letters that are darker than the plastic (no white lettering on black plastic, for example)

Double-Shot Injection Molding
With this method, the keycap actually consists of two pieces. The first piece is the outside of the keycap with the letter basically cut out of it, and the second piece is placed inside it with the lettering embossed to fit into the top piece. You can see it in this diagram:

This method of printing results in the highest quality keycaps possible. The edges of the letters are perfectly sharp, and it achieves the highest contrast, clearest lettering possible. Unfortunately, because of the very high price, only TG3 Electronics (Deck Keyboards) still uses this method on their keyboards, and Fentek and Signature Plastics can create custom caps with it.

Example: OCN Keycap


The easiest way to verify if a key is double shot molded is to check from underneath. You will be able to see the two different colored plastics.


Pros:

• Doesn't wear out, ever
• Perfect edges
• Highest contrast and visibility

Cons:

• Highest Cost
• Limited to two colors per key
• On worn keys you can sometimes feel the edge where the plastics meet

OCN Recommended Mechanical Keyboards
 

For a ever expanding list of OCN's recommended mechanical keyboard; please see this thread.

Keyboards By Switch Type

----Common Switch Types----

• Buckling Spring
  • IBM Model M - All Pre-1994, Some Post-1994
  • Most Unicomp Keyboards
• Topre
  • Happy Hacking Pro 2
  • Realforce
  • Epson InterKX IKXFKB
• Cherry MX Blue
  • iOne Scorpius M10
  • iOne Scorpius M10 BL
  • Leopold FC200R
  • Ducky DK-9008
  • Ducky DK-9000
  • Ducky DK-1008
  • Ducky DK-1087
  • Ducky DK-9008-G2
  • Cherry G80-3000 LSCRC-2
  • iOne Scorpius 35
  • Das Model S
• Cherry MX Brown
  • Filco FKBN104M/EB
  • Filco FKBN87M/EB
  • Leopold FC200R
  • Ducky DK-9008
  • Ducky DK-9000
  • Ducky DK-1008
  • Ducky DK-1087
  • Ducky DK-9008-G2
  • Filco FKB104M/EB
  • FKB22MB
  • Compaq MX 11800
  • Compaq 11802
  • Cherry G80-3000
• Cherry MX Red
  • Cherry G80-3600LYCEU-0
• Cherry MX Black
  • Deck Keyboards
  • Leopold FC200R
  • Ducky DK-9008-G2
  • Ducky DK-9008
  • Ducky DK-9000
  • Ducky DK-1008
  • Ducky DK-1087
  • Steelseries 7G
  • Cherry MX 11900
  • Cherry G80-3000LPCEU-0
• Simplified ALPS Black
  • ABS M1
• Simplified ALPS White
  • Matias Tactile Pro 2.0
  • Solidtek ASK-6600U
  • Solidtek KB-6600ABU
  • SIIG Minitouch
  • Kinesis Evolution
• Original ALPS Black
  • Dell AT101W
• Original ALPS White
  • Focus 2000
  • Focus 2001
  • Focus FK-5001
  • Unitek K-258
  • Nan Tan KB-6551
  
  

----Uncommon Switch Types----

• SMK "Monterey" Switches
  • Chicony KB-5181
• Cherry ML Black
  • Optimus Maximus
  • Cherry ML4100
  
  

Replacement Keycaps & Maintenance

Keycap Pullers:

• Ring Style Keycap Puller
• Wire Style Keycap Puller
• DIY method - Paper Clip
• DIY Method - Flat Head Screw Driver
• DIY Method - Flat Blade Knife

Extra Keycaps:

Cherry MX Keycaps

• Linux Keycaps
• Lime-Green Blank WSAD Keycaps (Blank Version)
• Lavender WSAD Keycaps
• OCN Flame Keycap
• Red Escape Key
• Click Clack Skull Keycap (available in Blue, Red, & Yellow)
• Blank Windows Bubble Keycap
• Windows flat keycap
• AliXpress has multiple colors in 37key sets

Alps Keycaps

• OCN Flame Keycap
• Red Escape Key

Topre Keycaps

• Lavender Labled WSAD Keycaps
• Lavender Blank WSAD Keycaps
• Blank Red Escape Key
• Red Escape Key
• Click Clack Skull Keycap (Blue or Red available)
• Happy Hacking Keyboard Key Sets
  • White Lettered | White Blank | Black Lettered | Black Blank

Cleaning
Every once in a while you may want to clean your keyboard. There are many ways of doing this, and can take anywhere from a few minutes to several hours depending on how much dirt you're trying to get out of it and exactly what needs to be cleaned. If you've just spilled a can of Pepsi on your board and don't know what to do, you've come to the right place.

A good PC tool to have right now is the DataVac as it can replace canned air and compressors.

Quick Cleaning
Keyboards can get dirty pretty quickly. I mean, let's be honest here; it's not like most of us actually wash our hands every single time we're about to sit down at the PC. And on top of that there's always dust and hair that can fall in-between the keys. So it's always good to give your board a quick cleaning every week or two.

1. Use canned air (or an air compressor if you don't care for convenience) to blow out any loose dust or dirt from underneath the keys.
2. Wipe the keytops and casing down with a clean cloth, dampened with isopropyl (rubbing) alcohol. Pay extra attention to any keys that you might be using the most frequently, such as WASD.
   • Note: On Filcos, use water instead of Alcohol. Filcos have a special coating on them that gets ruined if you use it.
3. If you're a heavy smoker and the casing seems to be yellowing, wipe it down with Windex.

Doing these things on a regular basis will keep your board looking great.

Deep Cleaning
If you've just gotten a used keyboard off of ebay that looks like it was used at a mechanic shop, or just spilled your drink right into it, your board needs a deep cleaning. If you do ever spill anything into it, make sure you clean it immediately. The longer you wait, the worse the cleanup is going to be - and may end up being next to impossible.

1. Take the keycaps off of the switches (see the next section for details on how to do this)
2. Open up the casing and take the PCB/membranes out. Each keyboard is different, but normally there's a combination of both screws underneath the board and tabs on the sides holding the top and bottom pieces together.
3. If you don't have a dishwasher or prefer not to use it, put both the keycaps and casing in a bath of warm water and dish soap, and let them soak for at least a good 30 minutes.
4. The process for cleaning off the circuitry varies depending on what sort of switches you have:
   • Cherry, Alps, and other similar switches: Place the entire PCB+switch assembly into a container of distilled water. Shake the board around vigorously so that the water can clean out the inside of the switches as well. To dry it out, shake it until you no longer hear any water stuck inside the switches. Then set it either on it's side or upside down to dry. Using a blow dryer to dry it is safe as long as you don't stick to one spot for too long, and canned air can help get the water out of the switches very quickly.
   • Membrane boards, including Rubber Domes and Buckling Springs: Separate the layers of membranes, and wipe them down with a damp cloth (distilled water only), and then again with a dry cloth. If the layers are fastened together, dip them into distilled water and flex and shake them around until they are as clean as they can get, then flap them around to get the water out. You may also be able to slip a cloth or paper towel in between them to dry them, but remember to check for any lint that gets stuck. Rubber domes should only be rinsed using distilled water at or close to room temperature (give or take a few degrees) - anything too hot or too cold can permanently alter their feel. The springs, hammers, steel plate, and plastic cover of Buckling Springs shouldn't need more than a quick rinse or wipe-down, but you can always use soap or isopropyl alcohol on them if they need it.
   • Rubber Dome on PCB, such as Topre: Rinse the domes in distilled water at or close to room temperature, rubbing with your fingers if anything is stuck badly to them. If it's a Topre capacitive board, the springs can be cleaned the same way or with a light concentration of dish soap or isopropyl alcohol. Wipe the PCB down with a cloth dampened with distilled water.
5. Whatever sort of internals your keyboard has, put them aside to dry at least overnight. If there were any ICs or other surface-mount electrical components that you had to get wet, a good way to speed up the process significantly is to use canned air to blow the water out from under them.
6. By the time you're done with the internals, the casing and keycaps should be ready. When taking them out of the dishwasher or soap bath, take them out and dry them with a towel one by one. If there is still any amount of dirt on them, rub them down with isopropyl alcohol and/or Windex. Isopropyl normally works better, but Windex gets certain things out without any effort that the dish soap may not have caught in a still bath, such as cigarette smoke residue.
7. Once you're absolutely positive that everything's dry, put it all back together.

Miscellaneous Resources

Keyboard Customization Guides
Dye Your Old White/Grey Keyboard


General Keyboard Information
Sandy's Keyboard Page\\
Deskthority
GeekHack Wiki
Official "Removing Stabilized Filco Keys" Directions

Switch Technologies
Qwerter's Clinic Cherry MX Info
NKRO on Microsoft Sidewinder x4 - Resistance method
All About Scissor Switches

Programming
SharpKeys - Basic Keyboard Programming
Autohotkey - Advanced Keyboard Programming

Interfaces and Protocols
Interfacing the AT and PS/2 Keyboards
PS/2 Keyboard Interface
PS/2 Keyboard Protocol
XT Scancodes
AT, PS/2, and USB Scancodes
USB in a Nutshell


Switch Matrix and Actuation Design

Credits:
Original Guide Created by Manyak
Frequent Updates done by Tator Tot
Alps Section & Input on Buckling Springs thanks to ch_123
Animated Pictures of Cherry MX Switches in action are thanks to Lethal Squirrel on Geekhack
Animated Picture of the Buckling Spring Switch thanks to Qwerter's Clinic
Pictures of Keycaps thanks to Ripster on OCN & Geekhack