Custom Mechanical Keyboard Part II: Build Guide
This guide covers the second half of building a custom mechanical keyboard: assembling the case, plate, PCB, switches, and keycaps, plus programming the board and troubleshooting common issues. By the end, you’ll have a working keyboard and know how to fix the most frequent build problems.
Background: What “Part II� Means
If you’ve already chosen your parts (the “Part I� of keyboard building), Part II is the actual assembly and finishing. This includes mounting the PCB and plate into the case, installing stabilizers, soldering or hot-swapping switches, attaching keycaps, flashing firmware, and testing. It also covers the less obvious steps like lubing switches and tuning stabilizers that separate a decent build from a great one.
Many first-time builders find the assembly itself straightforward—the tricky parts are alignment, avoiding solder bridges, and getting the firmware to work. This guide walks through each stage in order, with specific tips for common mistakes.
What You Need Before Starting
Make sure you have all the parts and tools ready. Missing a screwdriver mid-build is annoying, but missing a stabilizer wire means you can’t finish at all.
- Parts: case, PCB, plate, switches, keycaps, stabilizers (if not pre-installed), screws, and any foam or gaskets that came with the case.
- Tools: screwdriver (usually Phillips #0 or #1), tweezers, switch puller, keycap puller, and optionally a soldering iron if your PCB isn’t hot-swap.
- Optional but recommended: switch lube, stabilizer grease, a small brush, and a soft mat to work on.
Check that your PCB and plate are compatible—most standard 60% and 65% boards use a universal layout, but some are proprietary. If you bought a kit, it should all match.
Step-by-Step Assembly
Follow these steps in order. The exact order can vary slightly by case design, but this works for the majority of tray-mount and gasket-mount keyboards.
- Install stabilizers (if not pre-installed). Snap the housing into the PCB, then insert the wire and clip the top housing. Test that the wire moves freely.
- Mount the PCB to the plate (for non-hot-swap). Place the plate over the PCB, aligning the switch holes with the solder pads. For hot-swap, you can often skip this and put switches in later.
- Insert switches (for hot-swap). Push each switch into the plate and PCB, making sure the pins go straight in. They should click into place without excessive force.
- Solder switches (if required). Heat the pad and apply solder, then remove the iron. Avoid bridging adjacent pads.
- Place the assembly into the case. Align the screw holes and secure with the provided screws. Do not over-tighten.
- Attach keycaps. Press each keycap onto the switch stem until it clicks. Use a keycap puller to adjust any that are crooked.
- Connect and test. Plug in the USB cable and test every key with a keyboard tester website or software.
If you have a gasket-mount case, the plate and PCB sit on silicone gaskets rather than screwing into standoffs. Follow the case’s manual for that specific mount.
Programming and Firmware
Most custom mechanical keyboards run open-source firmware like QMK or VIA. QMK requires compiling and flashing, while VIA allows real-time key remapping without flashing.
- QMK: Download the QMK MSYS environment (Windows) or use the QMK Toolbox to flash pre-compiled hex files. You’ll need to know your keyboard’s name (e.g., “dz60� or “kbd67�) and the bootloader key combination (often Esc or the reset button on the PCB).
- VIA: If your PCB supports VIA, download the VIA app and load the JSON file for your board. You can then remap keys, change lighting, and create macros in real time.
- Flashing: Put the PCB into bootloader mode (usually by holding the reset button while plugging in), then flash the firmware file. After that, the keyboard should work immediately.
Common issue: the keyboard isn’t recognized. Try a different USB port, a different cable (some cables are charge-only), and ensure you’ve installed the correct drivers (on Windows, the keyboard may show as “ATmega32U4� or similar).
Common Problems and Fixes
Even experienced builders hit snags. Here are the most frequent issues and how to resolve them.
- Key not registering: For hot-swap, reseat the switch—bent pins are the usual cause. For soldered, reflow the joint or check for a cold solder.
- Stabilizer rattle: Apply grease to the wire where it touches the housing, and make sure the wire is seated in the stem’s clip.
- Switch feels scratchy: This is normal for unlubed switches. You can lube them with a thin layer of Krytox 205g0 or similar on the stem and housing.
- PCB not fitting in case: Check that the USB port aligns with the case cutout. Some cases require removing a small piece of the PCB or using a different mounting position.
- Firmware won’t flash: Ensure you’re in bootloader mode and using the correct file. Try a different USB cable and a direct port (not a hub).
If a key types the wrong character, it’s likely a firmware layout issue—remap it in VIA or recompile QMK with the correct layout.
Costs and Time
Building a custom keyboard is generally more expensive than buying a prebuilt, but you get exactly what you want. A basic kit (case, PCB, plate) starts around $80–$150, switches range from $20–$60 for a set, and keycaps can be $30–$100. High-end parts can push the total well above $300.
Assembly time varies: a hot-swap build with pre-lubed switches takes about 1–2 hours; a soldered build with lubing and stabilizer tuning can take 4–6 hours. The first build always takes longer as you learn the process.
Safety and Precautions
Soldering involves high heat—always work in a ventilated area and never touch the iron tip. Use a soldering iron stand and unplug it when not in use. Avoid inhaling solder fumes; a small fan or fume extractor helps.
When inserting switches, be gentle. Forcing a switch into a hot-swap socket can damage the socket. If it doesn’t go in easily, check that the pins are straight and aligned.
Also, be careful with the PCB’s ESD (electrostatic discharge). Touch a metal object before handling the PCB to avoid static damage, especially in dry climates.
Alternatives to Building
If you’re not sure about building, consider a prebuilt custom (like a Keychron or Epomaker) that offers hot-swap sockets and VIA support. You can still customize switches and keycaps later without soldering.
Another option is a barebones kit—you only add switches and keycaps, which is simpler than a full build. Or, if you want the experience but not the risk, buy a cheap soldering practice kit first.
Frequently Asked Questions
Do I need to lube switches?
No, but it improves feel and reduces scratchiness. Factory-lubed switches (like Gateron Pro) are fine as-is. If you lube, do it sparingly—too much can make switches feel mushy.
What’s the difference between hot-swap and soldered?
Hot-swap lets you change switches without soldering, using sockets on the PCB. Soldered is permanent but often cheaper and offers more switch compatibility. For beginners, hot-swap is recommended.
Can I use any keycaps?
Most keycaps fit standard MX-style switches. Check the layout (e.g., ANSI vs ISO) and the bottom row (some have non-standard sizes). Cherry and OEM profiles are the most common.
Why is my spacebar rattling?
Rattle usually comes from the stabilizer wire hitting the housing. Apply grease to the wire ends and the plastic contact points. Also ensure the wire is fully seated in the stem clips.
How do I know if my PCB is in bootloader mode?
Many boards have a reset button on the back; hold it while plugging in. Others use a key combination (like holding Esc). Check your board’s documentation. The computer should show a new USB device.
What if I break a switch pin?
If you bend a pin, you can often straighten it with tweezers. If it breaks off, the switch won’t work—you’ll need to replace that switch. Hot-swap sockets are replaceable, but soldered ones require desoldering.
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