This revision separates the documented Stillson jaw action from the one exact quantity available from declared force geometry: applied torque about the pipe axis.
Stillson Applied-Torque Explorer
Choose a declared force, radius from the pipe axis to the hand, angle between the radius vector and force, and a display-only pipe diameter. The worksheet calculates the applied moment; it does not predict grip or safe capacity.
Equation Used
- Force F is a declared point force applied at radius r from the pipe axis.
- Theta is the included angle between the radius vector and force vector.
- The pipe diameter changes the drawing only and does not enter the torque identity.
- The jaw/frame rocking animation is qualitative and follows the patented closing topology.
- Jaw contact, tooth penetration, friction, material hardness, pipe deformation, wrench strength, thread condition, joint preload and safe capacity are excluded.
Removes unsupported clamp-force, efficiency, friction and grip-margin outputs; retains exact declared applied-torque geometry and the documented Stillson topology.
A pivoted frame lets handle pressure close the jaws
Stillson's 1869 patent identifies a lower fixed toothed jaw, an adjustable oppositely toothed jaw on a threaded shank, an adjusting nut, a spring and a frame pivoted on the handle shank. With the pipe placed between the jaws, handle pressure turns the frame about its pivot and closes the jaws; releasing pressure releases the pipe.
The animation preserves that topology but does not solve contact force or tooth penetration.
Designed for round pipe and threaded fittings
RIDGID's current Pipe Wrench Use Guide describes pipe wrenches as hand tools for turning pipe and tightening or loosening threaded pipe connections with round threaded fittings. It warns that the teeth penetrate and mark the stock and that high forces can crush or oval thinner-wall pipe.
Use the correct current manufacturer instructions and rated size for the selected wrench. This page is not an operating procedure.
The supported calculation is the applied force moment
OpenStax defines torque magnitude as r F sin(theta), where theta is the included angle between the position vector and the force. The perpendicular force component is F sin(theta), and the perpendicular moment arm is r sin(theta).
No universal conversion from that applied moment to Stillson jaw clamp force is supported by the patent or manufacturer guide.
A declared force-geometry example
A 220 N force applied 0.32 m from the pipe axis at 90 degrees gives 70.4 N·m, or 51.9 lb·ft, of applied moment. That arithmetic does not establish whether the wrench, pipe or joint can safely accept it.
Applied torque is not grip capacity
The former worksheet assumed fixed 0.65 mechanism efficiency and 0.70 friction coefficient, then reported jaw clamp force and grip margin. Those quantities depend on actual jaw, pivot, contact, tooth, material and pipe geometry and are removed.
Unsupported gap, tooth pitch, hardness, torque-limit, joint-tightness, failure threshold, brand and field-case claims are also removed. Follow the exact tool and fitting instructions.
Stillson worksheet questions
Does the torque result rate the wrench?
No. It is only the moment of the declared force vector.
Does pipe diameter change the calculated moment?
No. It changes only the illustrative pipe circle.
Does the animation predict clamp force?
No. Jaw closure is qualitative.
What does the manufacturer guide require?
Inspect the tool, use it only on suitable round stock, choose the proper size, keep teeth clean and sharp, and remove damaged or modified wrenches from service.
Stillson pipe-wrench references
- Daniel C. Stillson, US patent 95,744: fixed and adjustable oppositely toothed jaws, nut, spring, pivoted frame and pressure-operated closing action.
- RIDGID Pipe Wrench Use Guide: documented parts, inspection, correct round-stock use, size limits and crushing/marking hazards.
- OpenStax University Physics, Torque: torque magnitude r F sin(theta), perpendicular force and moment-arm relationships.
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