Build a DIY Ultrasonic Cleaner for PCBs, Jewelry, and Small Parts

A benchtop ultrasonic cleaner is one of those tools that quietly earns its keep once you have one — stripping flux residue off a freshly soldered board, restoring tarnished jewelry, degreasing small CNC and laser parts, and cleaning clogged 3D printer nozzles all take minutes instead of scrubbing sessions. Commercial units are inexpensive for tiny jewelry-cleaner sizes but jump in price fast once you want a tank big enough for PCB panels or small mechanical parts. This project builds a right-sized ultrasonic cleaner from a transducer/driver kit and a stainless tray, sized and built exactly for the parts you actually clean.

How Ultrasonic Cleaning Works

A piezoelectric transducer bonded to the underside of a metal tank vibrates at ultrasonic frequency (typically 40kHz for small parts cleaning) when driven by an AC signal from the generator board. Those vibrations create and instantly collapse millions of microscopic vacuum bubbles in the cleaning fluid — a process called cavitation — and the implosion of those bubbles against a submerged part's surface scrubs away contamination in crevices and blind holes that a brush or cloth physically can't reach. This is why ultrasonic cleaning is so effective on PCBs (getting flux out from under low-profile SMD components) and jewelry (cleaning inside filigree and prong settings).

Choosing the Transducer and Driver

Ultrasonic transducer/driver kits are sold as matched pairs — buying the two separately and mismatching frequency or wattage rating is the most common way to end up with a unit that either doesn't cavitate properly or burns out the driver board. For a small parts tank (roughly the footprint of a stainless steel tray sized for PCBs and jewelry), two 40kHz 50W transducers driven by a matched generator board is a solid, easy-to-source configuration. 40kHz is the standard frequency for general parts and PCB cleaning; lower frequencies (28kHz) are more aggressive and better suited to heavily soiled industrial parts, while higher frequencies (80kHz+) are gentler and used for delicate optics — not needed here.

Building the Tank

Select the tray. A welded-seam (not folded-corner) stainless steel tray is important — folded corners can leak once submerged and vibrating for extended periods. Size it to your largest typical part with margin for the parts basket.
Clean and rough the mounting surface. On the underside of the tray, lightly abrade the area where each transducer will bond so the epoxy has a mechanical grip, then degrease with isopropyl alcohol.
Bond the transducers. Mix a generous amount of two-part epoxy and bond each transducer flat against the underside of the tank, applying firm even pressure while it cures (a clamp or heavy weight works well) — air gaps or an uneven bond line significantly reduce cavitation efficiency and can cause the transducer to overheat and fail early. Let the epoxy fully cure per the manufacturer's time before powering anything on.
Route the transducer leads. Drill a small pass-through hole above the tank's waterline for the transducer wires, and seal around the wire pass-through with silicone sealant to keep it fully watertight.

Wiring the Driver Electronics

Mount the generator driver board inside a project enclosure separate from the tank itself — this keeps the electronics away from splashes and lets you position the control box wherever is convenient on the bench. Wire the transducers to the driver board's output terminals (most boards clearly mark a two-wire output per transducer, or a shared output for a parallel pair), and wire the 24V DC supply into the driver's input terminals, matching polarity.

Add a panel-mount rocker switch in line with the power input for a master on/off, and wire in a digital timer relay module between the switch and the driver board so a cleaning cycle runs for a set duration (5–15 minutes is typical) and shuts off automatically rather than needing to be watched and switched off manually.

Safety

Electrical isolation: keep all mains-adjacent wiring (the AC-to-24V power supply) fully enclosed and away from any splash zone; the low-voltage DC side that actually reaches the tank area is the only wiring that should be anywhere near liquid.
Never run the tank dry. Transducers rely on the fluid to carry away the heat they generate; running the driver with an empty or nearly empty tank overheats and can permanently damage the transducers within seconds.
Solvent selection and ventilation: isopropyl alcohol is flammable and its vapor is heavier than air — use it in a well-ventilated area away from ignition sources, and never use a flammable solvent in a tank that isn't rated and sealed for it. For most PCB and general parts cleaning, a water-based ultrasonic cleaning solution or diluted dish soap works just as well as IPA and carries none of the flammability risk; reserve straight IPA for flux removal where water-based cleaners underperform.
Heat buildup during long cycles: cavitation itself generates some heat in the fluid over extended runs — don't run back-to-back long cycles without letting the tank cool, and never touch the transducers directly while the unit is running.

Cleaning Solution Guide

ApplicationRecommended SolutionNotes PCB flux removal99% isopropyl alcoholExcellent flux solvency; use in a ventilated area, away from open flame General small parts degreasing (CNC/laser hardware, bits, nozzles)Warm water + a few drops of dish soapCheap, effective, non-flammable, safe for most metals Jewelry (gold, silver, most gemstones)Warm water + a small amount of mild ammonia-free jewelry cleanerAvoid ultrasonic cleaning on porous stones (opal, turquoise, pearl) or already-loose settings — the vibration can worsen existing cracks or loosen stones further Rusty or heavily oxidized small partsDiluted citric acid or commercial rust-remover solutionRinse and dry thoroughly afterward to prevent flash rusting

Using the Cleaner

Fill the tank with enough solution to fully submerge the parts (never operate with the tank empty or under-filled), place parts in the mesh basket rather than directly on the tank floor to keep them clear of the transducers and avoid direct contact damping the vibration, and run a 5–10 minute cycle for lightly soiled parts, up to 15–20 minutes for heavier flux or grime. Rinse cleaned parts with clean water (or a final IPA rinse for PCBs, to displace any moisture before re-powering a board) and dry thoroughly before reassembly or storage to prevent oxidation.

Beyond the obvious PCB and jewelry use cases, this build earns its bench space fast on 3D printer nozzles pulled for cold-pull cleaning, laser lens housings, small CNC end mills gummed up with resin or aluminum residue, and any small hardware pulled from long-term storage that's picked up a layer of oxidation or old lubricant — a five-minute ultrasonic cycle replaces what would otherwise be a fiddly hand-scrubbing session for all of them.

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