Practice before you touch the kit

Your first twenty solder joints will be bad. This is not pessimism, it is scheduling. Every solderer's first joints are lumpy, cold, or bridged, the same way everyone's first pancake is a write-off. The only question is where those bad joints happen: on a ten-dollar practice board that goes in a drawer afterward, or on the one Lily58 PCB you own.

That PCB deserves a moment of respect before we go on. Of everything in your kit bag, it is the single part that is genuinely annoying to replace. Switches come in bags of spares, diodes cost pennies apiece, but the PCB is a specific board from a specific shop, often overseas, and a replacement means CAD 25 to 40 plus shipping plus one to three weeks of waiting while your half-built keyboard stares at you (Chapter 4 has the sourcing details). And a lifted pad on it (the injury from Chapter 6, where the copper ring tears off the board) is the kind of damage that turns into an hour of rework, or a dead key, or that replacement order.

So the deal this chapter offers is: spend roughly the cost of a pizza and one relaxed evening, and arrive at the real build with hands that already know the ritual. Flight school before the airliner, exactly as promised in the introduction.

What to buy for practice

You need something with pads and holes that does not matter. Three good options, all findable on amazon.ca (search the quoted phrases; as always, prices are approximate as of mid-2026 and the specific listings rotate):

My recommendation for this book's path: the raw parts (for Lab 1), one practice or gadget kit (for Lab 2), and the SMD trainer (for Lab 3). Total damage around CAD 40, and you can trim that by skipping the gadget kit and doing Lab 2 on more perfboard.

Don't be confused. Perfboard and a practice kit PCB look similar but behave differently. Perfboard (perforated board) is a grid of independent holes, each with its own little copper ring and no connections between them; you supply the parts and there is no circuit, just joints. A kit PCB has printed copper traces connecting the pads into a working circuit, plus printed labels telling you what goes where. Perfboard is for repetitions; kits are for rehearsing the sequence of a real build. You want both experiences, which is why there are three labs.

A note on the iron: practice with the exact iron, tip, and solder you will use on the Lily58. The point of practice is calibrating your hands to your tools, so do not borrow a friend's station for the labs and then build with your own.

Lab 1: twenty joints on perfboard

Pure repetitions. No circuit, no polarity, no stakes. Just the ritual from Chapter 6, twenty times, with inspection.

1. Set up the bench exactly as in the Chapter 6 bench lab: mat, stand, cable routed, window open, fan across, lamp on, glasses within reach. Every lab starts this way until it is automatic.
2. Prepare ten resistors. Bend both legs of each resistor down at right angles so it looks like a staple (fingers are fine; the plastic body should sit flat between the bends). Which resistor values? Irrelevant. We are using them as leg-delivery devices.
3. Populate the board. Push each resistor through the perfboard so its legs come out the copper side, spreading the ten parts out so you have working room. Splay each pair of legs outward maybe 30 degrees so the parts do not fall out when you flip the board.
4. Flip the board copper side up and prop it so it does not rock. (A strip of masking tape over the parts before flipping keeps them seated; the PCB holder or helping hands from Chapter 5 earns its money here.)
5. Solder all twenty joints, chanting the ritual. Heat pad and lead together, one second. Feed solder to the joint, one to two seconds. Solder off, iron off, hold still. Wipe and re-tin the tip every three or four joints. Do not rush, and do not stop to mourn a bad joint; note it and move on.
6. Clip the legs with flush cutters, glasses ON, just above each solder cone. Cup your free hand over the cutter, or aim the board so the leg flies at the mat, not across the room.
7. Inspect all twenty against the checklist (below), under your lamp, tilting the board so light rakes across the joints. Grade each joint out loud: good, cold, ball, too much.

Expect the first five to be ugly. Genuinely. Lumps, dull spots, one pad you had to poke at three times. Around joint eight or ten, something clicks: the solder starts flowing for you instead of despite you, and the joints start coming out identical. That click is the entire purpose of this lab.

You are done when... all twenty joints are soldered, clipped, and graded, and your last five in a row pass the checklist without excuses.

The good-joint checklist

For every joint, ask:

• Shape: a concave cone (volcano sides curving inward), not a ball, not a flat splat.
• Shine: bright and smooth for leaded solder (lead-free is allowed to be satin; judge it on shape).
• Wetting: solder visibly feathers onto the pad AND climbs the lead, no dark crack ringing either.
• Coverage: the whole pad ring is wetted, and the lead's silhouette still shows through the cone (buried lead means too much solder).
• Neighbours: no strand or blob reaching toward the pad next door.

Lab 2: build a full practice kit

Lab 1 taught the joint. This lab teaches the build: reading a board's printed labels, placing parts in order, and above all, respecting polarity.

Some components work either way around; some absolutely do not. A resistor has no polarity. An LED (light-emitting diode) does: it passes current in one direction only, and installed backward it simply does nothing. The convention: the long leg is positive (the anode), and the LED's plastic body usually has a flattened edge on the negative side, matching a marking on the board.

Why belabour this on a ten-dollar toy? Because the Lily58 is full of diodes (one per key; Chapter 3 explains why they exist), and a diode installed backward means a key that types nothing. An LED is just a diode that lights up, so every polarity check you perform in this lab is a direct rehearsal of the discipline that makes Chapter 10 go smoothly. Backward diodes are the number one first-build defect, and this is where you vaccinate yourself.

1. Unpack the kit and inventory it against its parts list before heating anything. (Also a rehearsal: Chapter 9 does exactly this for the Lily58.)
2. Solder lowest parts first: resistors and diodes flat against the board, then upright parts, then bulky parts. Short parts first means the board still lies flat on the mat for as long as possible.
3. Check polarity before every diode, LED, buzzer, and electrolytic capacitor. Long leg to the positive marking, flat edge to the flat marking. Say it out loud: "long leg, plus." Check, insert, check again, then solder. Ten seconds of checking beats ten minutes of desoldering.
4. Solder, clip, inspect in batches of a few parts, running the Lab 1 checklist each time.
5. Power it up per the kit's instructions (usually a coin cell or battery pack). Blinking lights or an obnoxious noise is your diploma.

If it does not work: do not despair, diagnose. Check every polarized part's orientation first, then reinspect every joint for the villains from Chapter 6 (a cold joint or a ball that never wetted is an open circuit). This debugging loop is, again, a rehearsal: it is a miniature of Chapter 13.

You are done when... the kit does its thing when powered, and every joint on the back passes the checklist.

Lab 3: surface-mount practice (the keyboard-specific one)

Here is where keyboard building departs from generic practice kits. Through-hole parts poke through the board; surface-mount parts (SMD, surface-mount device) sit flat on the board, soldered to bare pads on the surface, with no holes and no legs to grip. Two of the Lily58's part types are surface-mount or close to it:

• The diodes in most modern Lily58 kits are 1N4148W diodes in a package called SOD-123: a black grain of rice, about 3 by 1.5 millimetres, with a flat metal tab at each end and a painted line marking the cathode (the direction matters, as always).
• The hotswap sockets (the sockets that let you push switches in without soldering them, from Chapter 2) are surface-mount too: each one has two metal wings that solder to two big pads on the back of the board.

Neither can be soldered with the through-hole ritual, because there is no lead to heat and nothing holding the part in place. The SMD technique instead goes: anchor one end, then do the other.

1. Tin one pad. Touch the iron to one of the part's two pads and feed a small blob of solder onto it. Just that pad. Remove the iron; the blob freezes into a little mound.
2. Slide the part in while reheating. Pick up the part with tweezers (fingers are hopeless at this scale). Reheat the mound so it goes molten, and slide the part's end into the molten solder, holding it flat and aligned. Remove the iron, hold the part still with the tweezers for a second while the solder freezes. The part is now anchored.
3. Inspect the anchor. Flat against the board? Aligned with both pads? Polarity line pointing the right way (for the diode)? If not, reheat and nudge; the anchor is cheap to redo now.
4. Solder the free end normally. Heat that pad and the part's metal tab together, feed a little solder, done. This joint is easy because the part cannot move anymore.
5. Optionally, touch up the anchor end with a dab of fresh solder if the first mound looks lumpy (it often does, since it was soldered without flux flowing at the perfect moment).

Practice this on the SMD trainer board (search "SMD soldering practice board", around CAD 10-15; get one whose parts go down to about the "0805" size, roughly the size of the Lily58's diodes, and do not worry about the dust-speck sizes). Some Lily58 kits also ship a couple of spare diodes and the PCB sometimes has unused pads; spares are fair game after the trainer, never as your first attempt.

Do at least ten SMD parts. The skill being trained is the three-way coordination of tweezers, iron, and eyes, and it arrives around part six.

You are done when... you can place an SMD part flat, aligned, and wetted at both ends in under a minute, without the tweezers slipping.

How to grade yourself

Three tests, cheapest first:

• The visual checklist from Lab 1, on every joint, under raking light. This catches most problems.
• The tug test. Grip the component (or its clipped lead stub) with tweezers and pull, firmly, like you mean it. A wetted joint does not care. A cold joint or an unwetted ball pops off or visibly shifts. Better it fails in your hand tonight than in your keyboard next month.
• The continuity beep. Set your multimeter (Chapter 5) to continuity mode (the icon that looks like a sound wave or a diode; it beeps when the probes are connected by metal). Put one probe on the component's lead above the joint and the other on the copper pad or its trace. A beep means electrical continuity through the joint. On the practice kit you can also beep across a trace from one part to the next. No beep across a joint that looks fine is the signature of a cold joint or hidden crack.

Troubleshooting your technique

When practice misbehaves, the symptom names the cause:

The bar: ten consecutive good joints

Here is the gate between practice and the real build, and it is deliberately strict: ten consecutive joints that pass the visual checklist and the tug test, with no do-overs in the streak. One dud resets the count. Then the same standard for SMD: five consecutive parts, flat and wetted at both ends.

This usually takes one to two evenings from a standing start. If it takes three, that is fine; perfboard is patient and the Lily58 is not going anywhere. What you must not do is talk yourself into "close enough" at seven joints, because the Lily58 will ask you for over a hundred joints in a row, and the build is only as reliable as your worst one.

Takeaways

• Practice on worthless boards because the Lily58 PCB is the one part that is slow and annoying to replace.
• CAD 25 to 40 of practice gear from amazon.ca covers all three labs: resistors and perfboard for repetitions, a practice kit for polarity and sequence, an SMD trainer for the keyboard-specific skill.
• Polarity discipline ("long leg, plus"; check, insert, check again) is the habit that prevents the number one first-build defect: backward diodes.
• SMD technique is tin one pad, slide the part in molten solder with tweezers, then solder the free end.
• Grade with three tools: eyes (the checklist), hands (the tug test), meter (the continuity beep).
• The gate: ten consecutive good joints, plus five consecutive clean SMD parts. Strict on purpose.

There is one more skill to bank before the build, and it is the one that turns mistakes from disasters into detours: taking solder off. Every builder desolders something eventually, and learning it on the practice board you just built (yes, we are going to partially un-build it) costs nothing.

👉 Next: Fixing mistakes: desoldering and rework.