TIC-TAC Escapement Desk Clock - real Graham escapement, weight driven, seconds dial (4 colours)

The GIF shows the real motion, computed by a contact simulation of the escapement and rendered frame by frame (slowed down about 4×): a desk-size skeleton clock movement that really goes TIC-TAC. A bag of coins (or M8 nuts) in a little bucket pulls a thread off a drum; three gears carry that torque to a 30-tooth Graham escape wheel; a gold anchor fixed to the pendulum lets it advance exactly one tooth per swing. Each tic and each tac moves the red seconds hand 2°, one full turn every 60 s.

What you get

• Skeleton frame in midnight blue with a gold pin-line inlaid in the front face, cream seconds ring with navy numbers, gold wheels, red hand. 133 × 100 × 173 mm, fits on a desk shelf.

• Graham dead-beat escapement: escape wheel Ø60 mm with 30 undercut teeth, anchor spanning 7.5 teeth, locking faces drawn as arcs centred on the anchor pivot (no recoil).

• Pendulum: flat rod + Ø32 mm bob with a red ring and cream sunburst, period 2/3 s (3 ticks per second). Fine regulation marks every 2 mm on the rod: moving the bob 2 mm changes the rate by about 0.9 %.

• Gear train (involute, 0.2 mm backlash): drum wheel 60 → pinion 10 on the seconds arbor, seconds wheel 36 → pinion 12 on the escape arbor. 30 teeth × 2/3 s × 36/12 = 60 s per turn of the hand; the drum turns once every 6 minutes.

• Winding: a printed ratchet (16 teeth) and a flexible click on the drum wheel. Turn the knurled drum backwards with a finger to wind; the train does not move.

• Weight: a little gold bucket with navy bands holds a stack of coins up to Ø27.5 mm (2 €, 500 ¥, 1 €, 25 ¢) or M8 nuts. Nominal load 145 g (bucket + 135 g of coins). It hangs behind the pendulum and falls through a hole in the base down to the table: 8.7 minutes of ticking per winding.

• Small HANMA inlaid in the base and on the back frame.

You also need

• 4 pieces of Ø3 mm steel rod (silver steel or 3 mm pins): 42, 33, 43 and 68 mm. Wheels press onto the rods (Ø2.85 holes); the rods turn in Ø3.5 holes in the frames. A tiny drop of light oil on the 8 pivots and the pallets helps.

• About 50 cm of thin strong thread (fishing line or braided thread) and ~135 g of coins or M8 nuts.

Printing

• Bambu Studio, A1 mini + AMS lite, 0.2 mm layers, no supports. Four plates, 6 h 11 min and 144 g in total:

• Plate 1, front frame + dial + hand: 1 h 40 min, 29 g (cream 9 g, navy 15 g, red 2 g, gold 2 g).

• Plate 2, back frame with the 4 pillars printed standing + pendulum rod: 0 h 56 min, 19 g (cream 1 g, navy 18 g).

• Plate 3, all wheels, anchor, bob, drum, ratchet and bucket: 2 h 32 min, 47 g (cream 1 g, gold 44 g, red 0 g, navy 3 g).

• Plate 4, base: 1 h 02 min, 50 g (cream 49 g, navy 1 g).

• AMS colours: gold, midnight navy, cream, red. Colour changes are only in the first or last 0.6 mm (inlays) and in two bands of the bucket, so swaps are few.

• The escape-wheel teeth are 0.42 mm at the tip: print plate 3 slowly (or with a 0.4 mm nozzle at 0.12-0.16 mm layers) and clean any stringing between teeth.

How it was checked

• Escapement: a contact simulation with the real 2D shapes (no scripted motion: the wheel advances only as far as the pallets let it). With the pendulum at ±4° the wheel advances 6.00, 6.00, 6.00° per swing: exactly half a tooth (6°), one tooth released on every tic and every tac. Recoil 0.0000° (true dead beat).

• Escapement angles: impulse (lift) 3.1° of pendulum, wheel turns 4.4° while pushing; rest/lock 1.3° (0.67 mm of safety); drop 1.6° (0.85 mm at the tooth tip). It works for any amplitude from ±2.2° to ±6.1°.

• Controls that must fail, and do: pallets 1.0 mm (or 0.6 mm) longer jam the wheel; ±1.8° swing does not release teeth; gears shifted half a tooth collide (7.6 and 3.1 mm²).

• Period: the pendulum is a real physical pendulum (rod + bob), its moment of inertia taken from the meshes: L = I/(m·d) = 110.44 mm, T = 2π√(L/g) = 0.6667 s. Train: 30 × 0.6667 s × 36/12 = 60.00 s per turn, and in 90 swings the assembled model turns the hand exactly −360°.

• Torque vs friction (cautious, dry PLA): 145 g on a Ø14.5 drum gives 10.3 mN·m, 0.285 mN·m at the escape wheel after 0.80 per gear mesh and 0.92 per arbor. Per swing the pendulum gets 15.2 µJ and loses 6.2 (pivot) + 0.9 (air) + 8.1 (pallet friction) µJ, so it settles at ±4.3°. It would keep going with only 52 g: ×2.8 margin. With 25 g it stops (control).

• Kinematics with the real 3D meshes at 40 positions over one full swing (and the weight going from top to bottom): no part enters another (0.000 mm³), at least 0.50 mm between parts that move relative to each other, the steel arbors stay ≥ 0.24 mm from everything not mounted on them; escapement and gears touch without penetrating. Also clear at ±6.1° (0.50 mm). Controls: pendulum 3 mm forward hits the back frame, weight 6 mm forward hits the bob, wheel 3° ahead cuts the pallet.

• Printing: every plate fits 175 × 175, colours do not overlap (0.000 mm³), every part sits on the bed, 0 mm² of overhang above 45° (only the short bridge of the bob slot). Centre of gravity 41 mm inside the base edge with the weight loaded.

Español

Juguete de escape de reloj que hace TIC-TAC de verdad: una pesa (vasito con monedas o tuercas M8) mueve tres engranajes y una rueda de escape Graham de 30 dientes; el áncora del péndulo (2/3 s) suelta un diente en cada tic y la aguja de segundos da la vuelta en 60 s. Estilo esqueleto en azul noche, latón y crema, 173 mm de alto, 4 placas sin soportes en el A1 mini con AMS (144 g). Escape, periodo, par y choques comprobados en código.

العربية

لعبة آلية ساعة تصدر تك-تاك حقيقية: ثقل صغير (كوب فيه عملات معدنية أو صواميل M8) يدير ثلاثة تروس وعجلة ميزان من نوع غراهام بثلاثين سنا، ومرساة البندول (دورته ثلثا ثانية) تطلق سنا واحدة مع كل دقة، فيدور عقرب الثواني دورة كاملة كل 60 ثانية. هيكل مفرغ بالأزرق الداكن والذهبي والكريمي، ارتفاعه 173 مم، أربع لوحات طباعة بدون دعامات على A1 mini مع AMS.