§M4c mentioned that every part in this project gets washed in two tubs of IPA and cured under "a custom UV curing station." This is that station. It's a nail-polish lamp with its safety timer shorted out and four heatsinks taped to its back, and it has post-cured every resin part in this project for the price of a sandwich.
The real appliance costs real money
The proper tool here is a wash-and-cure machine. Anycubic's current one lists at $129, on sale for $89 as I write this [22]. That's a reasonable product, but it's also most of the cost of a second printer, and all it fundamentally does is spin parts in solvent and shine UV on them for a set time.
The washing half I already had, two plastic tubs of 99% isopropyl alcohol, dirty bath then clean bath (the workflow is in §M4c). The curing half needs a UV source that can run for minutes at a time, and the beauty industry mass-produces exactly that. Gel-nail curing lamps run in the same near-UV band hobby resins cure in (~405 nm class, general knowledge, since the listing doesn't state a wavelength). Mine is an XCHENIMO portable LED nail lamp from Coupang. I paid 5,990 KRW for it, about $4.10, and the same listing showed 3,990 KRW (about $2.75) when I screenshotted it for this chapter. Coupang prices drift around [20, 23].
So it was a $4 lamp instead of a $90 machine, with one catch.
The 30-second timer
A nail lamp is built to cure a thin, flat coat of polish on fingernails, so mine switches itself off about 30 seconds after you press the button. That's the right behavior for its real job, and it is presumably also what keeps the UV LED modules from overheating on long runs.
Resin parts are the opposite case. They're big, they have several sides, and per the §M4c workflow each side needs 5–10 minutes of direct UV. Pressing a button every 30 seconds for an hour is not a workflow. The timer had to go.
Shorting the timer
On the lamp's control board, I bridged the part of the circuit responsible for the auto-off timing, using hand-cut, silicone-coated jumper wires soldered across it. That leaves the timing and on/off logic disabled entirely. Power the lamp and the LEDs are on, unplug it and they're off. The switch is now the cable. Which pads exactly? I never noted it, so I won't guess now. What I can vouch for is the joint itself, made with the same syringe flux and rosin-core solder as every board in §M3b [builder, 2026-08-07].
Removing a protection feature means inheriting the problem it was protecting against, and that showed up immediately. In continuous operation the LED modules climb to temperatures I wasn't comfortable with, the exact overheating the factory timer exists to prevent.
Becoming the cooling system
The fix was to give the board the heat path the factory never intended it to need. The LED board's metal back is the natural surface for it, so I mounted four aluminum heatsinks onto it with a thin layer of ARCTIC MX-4 thermal paste (the 4 g tube) [21], held in place with electrical tape.
That was enough. With the heatsinks on, the lamp runs for more than three hours continuously without significant heat buildup, which covers even a full multi-part, both-sides curing session with margin. The check was touch, not instrumentation. Fingers on the heatsinks and on the PCB, again and again over a run, feeling for buildup. No numbers, and I'm not inventing any. Staying comfortable to the touch for hours was the acceptance test [builder, 2026-08-07].
Cost box
| Item | Paid | Notes |
|---|---|---|
| XCHENIMO LED nail lamp (Coupang) | 5,990 KRW ≈ $4.10 | listing at 3,990 KRW ≈ $2.75 when screenshotted [20]. USD at 1 USD ≈ 1,453 KRW [23] |
| ARCTIC MX-4 thermal paste, 4 g | [21] | |
| Aluminum heatsinks ×4 | mounted with MX-4 + electrical tape | |
| Two plastic tubs + 99% IPA | the washing half (§M4c) | |
| · vs. commercial wash & cure | $89–129 | Anycubic Wash & Cure 3, store price [22] |
Even against the sale price, the lamp is roughly one twenty-second of the cost (Derived: $89 ÷ $4.10 ≈ 22×). What the whole station cost has to wait on the prices still missing from the table above.
Two caveats
Two things anyone copying this should hear. First, the timer I removed was a safety feature, and after the mod the lamp will happily cook itself if the cooling isn't there. The heatsinks are not optional. They are the replacement safety system, and I still don't leave it running unattended. Second, this thing is now a continuous near-UV source. It gets pointed down at parts, never toward eyes, and the IPA tubs stay well away from it, because warm alcohol vapor and a hot lamp are a bad combination.
What the printing chapters add up to
This chapter closes the printing arc. The full pipeline, built over four chapters: exposure calibrated per resin (2.6 s, §M4a), orientation and supports systematized (§M4b), clearances measured at 0.15/0.30 mm and a two-bath wash routine (§M4c), and now unlimited post-curing for about four dollars. Total investment beyond the printer itself: tubs, alcohol, a nail lamp, thermal paste, and a few evenings of mistakes.
Every functional part in the actuator chapters (the dome foot in §M2, the friction coupons in §M8, the flexure legs in the Phase 2 plans) comes out of exactly this pipeline. The fabrication capability the stick-slip actuator literature treats as exotic (§M1's "no 3D-printed SSPAs" gap) is, in practice, a bedroom setup held together by jumper wires and electrical tape. It just has to be calibrated like you mean it.