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The Flexible Shaft: Turning a Tool Round a Corner
Martin

ایجاد شده توسط

Martin

27. سپتامبر 2026NO
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The Flexible Shaft: Turning a Tool Round a Corner

A dentist's drill must reach any tooth at any angle while it spins. A rigid shaft cannot follow the hand; universal joints give a few fixed bends. James B. Morrison of St. Louis tried two answers. His dental engine of 1871 carried the drive by a belt over pivoted, sprung arms. A year earlier his US 106,498, *Improvement in Flexible Shafts*, dated 16 August 1870, carried it through "a wire spiral or helix … enveloped in a short piece of india-rubber pipe, which allows the free flexure of the helix", in sleeves that act as bearings, with an adjustable head holding the bur and a parallel bracket for the instrument tray. The flexible shaft outlived the dental use: it drives rotary tools, speedometers and hedge trimmers today. This rung works out why only thin wires can bend and keep turning, and makes a flexible shaft from wound spring wire.
مبتدی
About 3 hours

دستورالعمل‌ها

1

Bending stress, fatigue and torque

در حال بارگذاری دفترچهٔ Jupyter…
2

The sibling: belt over sprung arms

Morrison's other answer to the same problem carries the drive by a belt over pivoted arms. The embedded blueprint builds it; compare the two ways of reaching round a corner.
3

Read the 1870 flexible power-conveyer

Fig. 1 of US 106,498 shows the apparatus on a stand: a pulley shaft B, joined by a wire helix C in a rubber pipe c to a shaft section D, turning in a swivel-eye E; a double hinged parallel bracket H, I carrying the instrument tray L, which stays level however the bracket swings; and further helix sections R and t′ leading through a sleeve to the socket-head holding the burr U. The patent's three claims, in order: the flexible shaft with its enveloping sleeve, which gives journal-bearing to the enclosed shaft and the tool; an adjustable head joined to the sleeve by a hinge, so the tool can be set at any angle; and the combination with a parallel bracket that swings, rises and extends.
4

Wind a flexible shaft and drive it

Clamp a 3 mm steel rod in a cordless drill as a mandrel. Clamp one end of a length of 0.8 mm spring steel wire to the rod and, turning the drill slowly, wind a close helix about 400 mm long, every turn touching the last. Slide it off: that is the core. Push a short length of steel rod into each end and secure it with a dab of solder or a crimped sleeve. Chuck one end in the drill; put a small drill bit in a pin chuck on the other end, held in a length of aluminium tube as the sleeve-bearing. Bend the core round a 100 mm radius and run the drill in the direction that tightens the coil: the bit turns and will drill soft wood. Reverse the drill: the coil opens, winds up and barely turns the bit. Compare with a commercial rotary-tool flex shaft.

مواد مورد نیاز این مرحله:

سیم فولاد فنرسیم فولاد فنر1 قطعه
شمش میلگرد فولادیشمش میلگرد فولادی1 قطعه
لوله آلومینیومیلوله آلومینیومی1 قطعه
لحیم قلع-سربلحیم قلع-سرب1 قطعه
شفت انعطاف‌پذیر ابزار گردانشفت انعطاف‌پذیر ابزار گردان1 قطعه

ابزارهای مورد نیاز:

دریل شارژیدریل شارژی
مجموعه متهمجموعه مته
گیرهٔ رومیزیگیرهٔ رومیزی
هویههویه
دستکش کار چرمیدستکش کار چرمی
عینک ایمنی شفافعینک ایمنی شفاف
5

A flexible shaft that fails

Flexible shaft faults.

Flow

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6

History and honest limits

**James B. Morrison** of St. Louis was granted **US 106,498**, dated 16 August 1870, for his flexible power-conveyer "for dental and other purposes"; his treadle dental engine with sprung arms followed in 1871 (US 111,667). Flexible shafts with multi-layer wire cores now drive rotary tools, instrument cables and garden tools. **Honest limits.** The bending-stress figures are the simple beam formula for one wire; a real core's stresses depend on its winding. A hand-wound single helix is a demonstration, not a tool shaft — it will not last.

مواد

5

ابزارهای لازم

6

CC0 مالکیت عمومی

این نقشه تحت مجوز CC0 منتشر شده است. شما آزاد هستید آن را کپی، ویرایش، توزیع و برای هر هدفی بدون نیاز به اجازه استفاده کنید.

با خرید محصولات از طریق نقشه از سازنده حمایت کنید و او کمیسیون سازنده تعیین شده توسط فروشندگان، دریافت می‌کند یا یک نسخه جدید از این نقشه ایجاد کنید و آن را به عنوان اتصال در نقشه خود قرار دهید تا درآمد به اشتراک گذاشته شود.

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