David C":wpow77a0 said:
I thought he designed the lathe which turned a good quality woodscrew?
David
It's certainly true that Whitworth did a lot to improve machine tools, and was among the first to offer them for sale. However, most of the fundamental developments were by others, notably his mentor Henry Maudslay, and his fellow Maudslay apprentices Naysmith, Roberts and Clement. Also true that before Whitworth started selling machine tools, you had to build your own or commission one from a small band of competent mechanics. I don't know whether Whitworth offered woodscrew-making machinery, he certainly did make a very considerable range of products. However, he wasn't the man who mechanised woodscrew-making.
I've been having a bit of a rummage in the CC Towers library, and couple of references have surfaced. Firstly, LTC Rolt's 'Tools for the Job', in which he tells us that the laborious process of filing the thread onto a blank became an early candidate for mechanisation. In 1760, the brothers Job and William Wyatt of Tatenhill and Burton on Trent in Staffordshire developed two types of special-purpose lathes, one in which the smithed blank of wrought iron was held for the head to be filed, and then the slot cut by a revolving cutter. The blank then passedto a second lathe, on which the screw was cut by two opposing cutters fixed in a frame guided by a 'master screw'.
It seems that in 1776 the Wyatt brothers acquired a water-driven corn mill at Tatenhall to convert into a screw factory. For reasons unknown, this venture was a financial failure, and was sold as a going concern to Shorthouse, Wood and Co who improved the process and expended production to the extent that a second factory was opened in Hartshorn nearby. In 1792, they were producing 1,200 gross a week "by means of 36 engines, or lathes......They are made of various sizes from half-an-ounce to 30lb per gross".
Rolt goes on to say that this must be one of the earliest examples of mass production by means of special purpose machines. The methods patented by the brothers Wyatt were refined but not basically altered until 1854, when John Sutton Nettlefold, working under licence, re-equipped his Birmingham screw factory with American machinery for the production of the modern pointed taper woodscrew. Rolt doesn't state this, but it seems that credit for the pointed woodsrew lies in America, though I don't unfortunately know who, where or when.
The second reference to come to hand was 'One Good Turn; A Natural History of the Screwdriver and the Screw' by Witold Rybczynski. I think it's out of print, but Abebooks or similar should be able to dig up a copy. A small, and rather rambling book, but there's good research buried in it. It seems the origins of the woodscrew are obscure, but could go back to the 14th century. They became more common in the early 17th century as locks and hinges were fitted to furniture, and the butt hinge started to be used for entrance doors. The strap hinge could be attached by clenched nails; the butt hinge could not, as the nail could not be clenched in the doorframe. There was a thriving trade in screw-making in the West Midlands, the wrought iron blanks being made by smiths, and then passed to 'girders' (often home-based) who filed them up and cut the thread either by filing, or by cutting them in a small, primitive lathe, guiding the cutting tool by hand and eye only. The results were inconsistent, and often had shallow threads, and the time taken to make them rendered them expensive.
It seems that there were many attempts to improve the drivability of screws during the 19th century, but none were commercially successsful. It wasn't until the advent of automobile manufacture, and the need to power-drive lots of screws reliably, that the cross-point and Robertson types (square drive, socket in the screwhead) took hold - the 1930s.
