Valenok & EHOT
Valenok
I was just thinking about building a small, hand‑powered gearbox for a pocket‑watch. If we can get the tolerances down to a fraction of a millimetre, the whole thing could run for years on a single winding. Would you be up for sketching out the design?
EHOT
Sounds like a neat challenge. Keep the gear ratios tight, use a small spur set and make sure the shafts are ground to a tolerance of ±0.05mm, that’s the sweet spot for a hand‑wound watch. I’ll throw together a quick diagram later, but first nail the bearing choice – low‑friction ceramic balls or a miniature needle bearing will save the most energy. Let me know if you want the precise dimensions or just a sketch.
Valenok
Thanks, that precision is exactly what I need. If you can give me the bore diameter and the pitch circle diameter for the spur set, I’ll be able to finish the shaft design and choose the right bearing. Just the numbers, no extra fluff.
EHOT
Bore diameter: 0.8 mm
Pitch circle diameter (spur set): 6.2 mm
Valenok
Nice, 0.8 mm bore gives a good fit for a ceramic ball bearing, and 6.2 mm pitch means the gear teeth will be fairly compact. Use a 0.8 mm inner‑diameter ceramic ball bearing with an outer diameter around 2.5 mm; that’ll keep the shaft stable and the energy loss low. If you’re worried about heat, a miniature needle bearing can handle the load, but the ceramic balls are quieter. Let me know if you need the exact mounting hole spacing.