Physical construction

Panels

The top plate, main PCB, and back plate are all panelized as one piece.

1. Snap each of these panels into their own pieces by hand
2. Using pliers, break off the mousebite tabs.
3. You can use a file or sandpaper to file down the notches left by the tabs on the three panels until smooth. I find using a nail file works great.

Acrylic layers

There are three acrylic pieces:

• Acrylic shield - 1.5 mm - This is a piece of acrylic that is mounted above the components for aesthetics and minor component protection
• Middle acrylic - 2.5 mm - This piece sits between the keyswitch plate and main PCB
• Bottom acrylic - 2.0 mm - This piece sits between the main PCB and the bottom plate

Important!: Please check the datasheet or ask about the thickness variation/tolerance of the material that you are using. There can be a large (10%) variance in the material thickness. This is important because a total layer thickness of 3.5 mm must be maintained between the keyswitch plate and main PCB for proper switch mounting. Material thickness is also important because it determines the fastener lengths used.

Any variation from 2.5 mm in the middle acrylic layer can be made up with the silicone layer, which is often found sold in 0.1 mm increments in thickness. i.e. if your middle acrylic layer is found to be 2.8 mm thick, you can substitute the 1.0 mm silicone layer with a 0.7 mm silicone layer, etc.

Silicone layer

There is a 1.0 mm silicone layer that sits between the keyswitch plate and middle acrylic layer. This silicone is largely optional in my opinion, but I feel like there are some nice qualities to be had with the dampened feel and sound.

If you choose to omit this piece, the middle acrylic layer will now need to be 3.5 mm thick to make up for the missing silicone. Additionally, the layer thicknesses are not strict, but there should be 3.5 mm between keyswitch plate and main PCB for switches to mount properly.

Layers

• Acrylic shield - 1.5 mm framework-acrylic-shield.dxf (for component section)
• Threaded spacers - 10 mm (for component section)
• Top plate - 1.6 mm
• Silicone - 1.0 mm - framework-acrylic-upper.dxf
• Middle acrylic - 2.5 mm - framework-acrylic-upper.dxf
• Main PCB - 1.6 mm
• Bottom acrylic - 2.0 mm - framework-acrylic-lower.dxf
• Bottom plate - 1.6 mm

The total nominal thickness of all of these layers is 10.3 mm (excluding acrylic shield), but can vary slightly in the real world. Using 1.6 mm thick PCBs, the only critical dimension to maintain is the 3.5 mm total distance (1.0mm silicone + 2.5 mm acrylic) between the top plate and main PCB for switch mounting reasons.

Fasteners

It is important that fasteners use a button head. This is important in the keyswitch area so that keycaps don't interfere.

• 5x M2 x 4 mm button head (acrylic component shield)
• 14x M2 x 12 mm button head (9x keyswitch plate, 5x component section)
• 9x M2 nut (underneath key area)
• 5x M2 x 10 mm aluminum threaded spacer (acrylic component shield)

The nine M2 x 12 mm screws in the keyswitch area should be inserted from the top, with M2 nuts on the bottom of the keyboard.

Five M2 x 12 mm screws are inserted from the bottom of the component area into the five M2 x 10 mm aluminum threaded spacers.

Five M2 x 4 mm screws secure the acrylic component shield onto the M2 x 10 mm aluminum threaded spacers.

Rubber feet

This is largely user preference. I prefer to have a 6-7 degree tilt and have found the following to work very well for me:

• 2x McMaster-Carr, 95495K931
• 2x McMaster-Carr, 95495K701

Rotary encoder knob

The rotary encoder knob should be for a 6 mm d-shaft. The biggest knob diameter should be around 25 mm before it interferes with the adjacent keycaps. This choice is user preference. The knob that I recommend is:

• Digi-Key, OEJNI-90-4-7 Black
• Digi-Key, OEJNI-90-3-7 Silver

Bill of materials (electrical)

Obviously, the exact part does not matter, as long as it is functionally the same and has the same footprint. This is just an example BOM. Please reference the KiCAD project for component details.

Mfgr.	Mfgr. part #	Digi-Key part #	Designator	Qty	Common Name
On Shore Technology Inc.	ED281DT	ED3050-5-ND	U1	1	DIP Socket, 28-Pin 0.3"
Vishay Beyschlag/Draloric/BC Components	A104K15X7RF5TAA	1109PHCT-ND	C2, C3	2	Ceramic capacitor, 0.1 uF 50 V
AVX Corporation	SA102A220JAA	478-2426-1-ND	C4, C5	2	Ceramic capacitor, 22 pF 200 V
ON Semiconductor	BZX79C3V6	BZX79C3V6-ND	D1, D2	2	Zener diode, 500 mW 3.6V
ON Semiconductor	1N4148	1N4148FS-ND	D3 - D62	60	Diode, 1N4148 100 V 200 mA
GCT	USB4085-GF-A	2073-USB4085-GF-ACT-ND	J2	1	USB 2.0 Type C Receptacle
Stackpole Electronics Inc	RNMF14FTC10K0	S10KCACT-ND	R1	1	Resistor, 10 kOhm
Stackpole Electronics Inc	RNMF14FTC75R0	S75CACT-ND	R2, R3	2	Resistor, 75 Ohm
Stackpole Electronics Inc	RNF14FTD1K50	RNF14FTD1K50CT-ND	R4	1	Resistor, 1.5 kOhm
Stackpole Electronics Inc	RNMF14FAD5K10	RNMF14FAD5K10CT-ND	R5, R6	2	Resistor, 5.1 kOhm
TE Connectivity ALCOSWITCH Switches	1825910-6	450-1650-ND	SW1, SW2	2	Tactile switch, SPST-NO
Fox Electronics	FC4STCBMF16.0-BAG200	631-1108-ND	Y1	1	Crystal, 16 MHz
Panasonic Electronic Components	ECE-A1HKA4R7	P827-ND	C1	1	Electrolytic capacitor, 4.7 uF 50V
Microchip Technology	ATMEGA328P-PU	ATMEGA328P-PU-ND	U1	1	ATMega328P-PU
Harwin Inc.	M20-9980345	952-2120-ND	J1	1	Header, 6-pin 2x3
Bourns Inc.	PEC11R-4220F-S0024	PEC11R-4220F-S0024-ND	[*1]	1	Rotary encoder
Kaihua Electronics Co., Ltd.	CPG151101S11	[*2]	[*1]	62	Hotswap socket

[*1] There is no reference designator for this component the board, but it should be obvious which footprint it belongs to.

[*2] Digi-Key does not stock this, but it seems easy enough to find through many vendors online if you search for the part number or "kailh hotswap sockets".