Is it possible to machine a lathe more accurate than the one you machine it on? If so, how?

07 Mar.,2024

 

I endorse Michael G's post above – a very good question!

JA's post to look up the life and work of Henry Maudsley is a good starting point. The follow up to that would be to visit the Birmingham Centre Point which hopefully still has Joseph Whitworth's first lead screws, all three of them, (made from three screws hand chiselled and filed then each fitted to a lathe to remove error in the time old A-B, B-C, A-C. Don't bet on it though as some significant exhibits haven't seen the light of day for years!

A word here about what used to be the Birmingham Science Museum, now partially housed in the Centre Point building alongside City of Birmingham University (note: Not Birmingham University – that's in Edgbaston ). This facility is a shadow of the old Museum and some of that is down to its juxta-positioning to the C-o-B Media Studies and Performing Arts faculty next door. It has been dumbed down to now little more than a TV screen which alongside the exhibits does nothing to inform you of the object but rather berates the social injustices perpetrated on the 'victims' of capitalism forced to work in dingy work places!

As for more modern examples, when I was an apprentice at AH Ltd,. I worked on a Cincinnati vertical mill which had been fished out of the hold of the ship bringing it from the USA in 1941 (the ship had been sunk in Liverpool docks ) It had so much wear having been flogged to death by day and night shifts that the only way to accurately use it was by use of dial indicators and dead length bars (an early version of DRO, but actually ARO! ). This machine was used almost exclusively for 'fitters returns' where we 'fettled' parts which would not fit correctly due to some error. It often included easing a gearbox mating face by '0 thou, 3 thou, 8 thou, and 2 thou on the 4 corner mating edges. Another job was a lengthened leadscrew for a special machine which needed an extension shaft which had also to run in a housing at the point of the join – this meant the shaft had to be 'tongued and grooved' to an accuracy of 2 tenths of a thou runout between the two components.

I got a bar of chocolate off the foreman for that job.

The other machine I worked on was a No. 16 Universal which was part of an order in 1916 for Tsarist Russia, it had been rejected by the Russian on site Inspectors as being out of limits, so in Herbert tradition was put to work in making parts for there own machine tools! One component was the intricate drum cams for the cam auto machines Herbert's made. Backlash was eliminated by a wire rope and a sack of scrap iron hanging over a roller at the end of the table.

Martin

Edited By Oily Rag on 29/10/2021 07:51:48

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