The Screw-Back Button: Two Halves That Clamp the Cloth

"This invention relates to certain improvements in buttons, shirt-studs, and other like articles; and it has for its object to provide a means for readily securing a covering to the head of the button, and to provide for securing the button to the fabric to which it is to be attached without sewing." The bottom disk's "screw-threaded stem" is "passed through the aperture or eyelet from the opposite side of the fabric, engaged with the internal thread of the shank B and screwed up tightly, so that the fabric will be caught between the upper surface of disk E and the end of sleeve d". "Whenever the cloth covering becomes worn it may be easily replaced by detaching the parts of the button and assembling them as before; or the button may be readily transferred from one garment to another, and the covering changed to correspond with the fabric."

On a scrap of denim, fit one screw-back button as in the program, and sew an ordinary button on beside it. Loop strong thread under each button and hook the force meter to the loop. Hold the denim flat and pull each button straight out, slowly, reading the highest force before something gives. Note what gave: the thread, the cloth round the hole, or the button itself. Repeat on fresh cloth and compare.

**Carl E. S. Gederén** of Philadelphia filed US 206,103 on 29 April 1878; it is dated 16 July 1878. His claim is the detachable clamping disk that holds the cloth cover, together with the screwed top and bottom disks. **Honest limits.** The torque rule with K = 0.2 is an engineering rule of thumb, not a law; K changes with finish and lubrication. Thread sizes, friction and torques are examples. Your pull readings are the measurement.