From the Loftsmith Workshop
Hidden message lantern for LED tea lights, turn to reveal
A porthole lantern for a 38 mm LED tea light: two perforated discs look like random static until you turn the front dial and JOY appears. Each of the 200 pixels is a 2 x 2 block of 1.4 mm square holes (34 of them spell JOY at the default). Aligned, background pixels let light through 2 of their 4 holes and message pixels through none, and a thin white front layer also shows the message by day. Sliders set the message (JOY, YES, HI, XO, star, tree, heart, snowflake), dial diameter 88-120 mm, hole pitch 2.2-2.6 mm, dial running gap 0.15-0.35 mm and tea light diameter 36-42 mm. Three parts print
3 parts · 75 g · 96 × 49 × 104 mm
Ask for the sizes you want to tweak, e.g. “make the width adjustable”.
How to print it
Parts
- body · PLA, dark opaque (navy); first 0.4 mm wh · Face down on the bed (front disc first), drum and cradle rise straight up
About 51 g and 73 min (48 g dark plus 3 g white). Holds the fixed perforated disc, the snap groove, the flat land for the tea light and the index triangle.
- face-skin · PLA, white · Printed as the first two 0.2 mm layers of the body (filament 2)
Not a separate print: a colour change after 0.4 mm, done by AMS or by a manual pause. In daylight the message shows white through the dial. Turn the White front skin toggle off for a single-colour body.
- dial · PLA, dark opaque (navy) · Face down on the bed, fluted bezel rising up
About 12 g and 20 min. Second perforated disc with a fluted grip, an index notch and a 0.55 mm snap lip.
- back-cap · PLA, white · Outer face down, plug ring up
About 12 g and 20 min. Push-fit plate that glows behind the pattern; the 16 mm pull tab on top stands 7 mm above the drum so the cap comes off by hand.
Print settings
- Layer height
- 0.2 mm (the white skin is the first 2 layers)
- Walls
- 2
- Infill
- 15%
- Supports
- None. All three parts print flat, face down
- Notes
- At the default sliders all parts together take about 79 g and 1 h 59 min at 2 walls/15% (including about 1 g of purge for the two colour changes). With 3 walls they take about 94 g and 2 h 22 min. Print the body and dial in dark, opaque PLA and the back cap in white. For the body, change to dark fil
Hardware
- LED tea light, 36-42 mm diameter, about 16 mm tall · Not printed. Default slider fits a 38 mm one. LED only, never a flame candle.
Assembly
- Print the body face down: white for the first 0.4 mm, dark after that. Print the dial face down in the same dark PLA and the back cap outer face down in white.
- Push the dial straight onto the front of the drum until its lip clicks into the groove, then turn it once all the way round to check it runs freely.
- Switch the LED tea light on first, then slide it in from the back onto the flat land inside the drum.
- Press the white back cap into the back opening until its rim sits on the drum, with the pull tab at the top.
- Turn the dial until the notch on its rim lines up with the small triangle on top of the drum: the message appears. Turn it away to scramble it back into static.
- To switch the tea light off, pull the back cap off by its top tab, take the tea light out, switch it off and put it back.
Good to know
- LED tea lights only. PLA softens at about 55 C, so never use a flame candle.
- The tea light's switch is underneath it, so switch it on before the back cap goes in. Switching it off means pulling the back cap off by its top tab each time.
- It reads best from straight on. At the default 1.4 mm holes the two discs stay aligned within about 28 degrees of head-on, so seen from a steep angle it looks like static.
- Print the body and dial in a dark, opaque filament. Light or translucent filament lets light through the solid parts and weakens the contrast.
- The holes are 1.4 mm squares at the default pitch. Elephant's foot or over-extrusion can narrow them. If the glow is weak, raise Hole pitch; this makes the message smaller.
- On small windows (smaller dial, coarser pitch, larger tea light) the words and the snowflake switch to smaller pixel art. The size used for each preset is listed in the 'Every preset fits' checks.
- The dial is held by a 0.55 mm PLA snap lip; the snap check gives the ring stretch for the current and the smallest dial. It is meant to go on once, and repeated removal may wear the lip. If the dial binds or rattles, change Dial running gap.
- Messages are limited to the presets: JOY, YES, HI, XO, star, tree, heart and snowflake. A custom word needs a remix in the Studio.
- The fit, the snap and the light contrast were checked as geometry in the Loftsmith engine, not on a real print. Print the dial and body and test the snap and the reveal before giving one as a gift.
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