Just an anecdote (1) – Shifters

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

When I first started in industry there were still many traditional style machine shops with long rows of lathes , millers and other machines being operated by skilled workers .

These skilled workers were actually of several different grades and with various special skills for different types of work .

The best ones to watch for pure entertainment were the fully skilled production turners .

I have often watched a Model Engineer cutting a simple screw and taking about 209 cuts to get to size (or so it seemed) . These production turners could cut a 1 inch Acme feed screw to very good accuracy in FOUR cuts – bulk removal – finish to depth , finish left flank , finish right flank – done .

The other thing was when a plain bar had to have a large amount of metal removed in some places before detail turning could begin . Each production turner had his own pet 'shifter' for rapid bulk removal – generally a large sized HSS tool bit with all the rakes and clearances taken to extremes – like 40 degrees top rake (!) – but still with a rounded or angled off cutting corner . Using this tool and with all feeds and speeds at maximum and flood coolant a wheelbarrow could be filled with swarf every few minutes . Swarf was often one continuous ribbon as it came off the bar and most turners arranged chip breakers and/or tinplate catchers for safety .

These production turners made effective use on a regular basis of techniques amost forgotten now – like turning to a witness – and often had made in advance multiple duplicates of most commonly used tools to avoid 'down time' for sharpening .

There's a lot more to tell – perhaps someone else with similar memories can take up the tale .

Michael Williams .

[mickParticipant @mick65121]

I'm trying not to criticise another's working memories, but production turners most likely did a 5 year apprenticeship and were working a heavy industrial ( and therefore more stable) machine. I don't think any turner that I've worked with and I've worked with some pretty tasty ones, could cut an 1'' Acme thread to a good standard of accuracy in four cuts. Acme threads are a precision thread used for such things as machine lead screws, where minimal play between the screw and nut is paramount, making it one of the most difficult threads to cut. A skilled turner, in my experience, would use two tools, a roughing tool and a finishing tool to produce the thread form. The roughing tool would cut a few thou below the root diameter, while the finishing tool would cut both flanks together, while not removing any material from the base of the thread, therefore avoiding any juddering which would effect the accuracy of the two flanks, and yes, I've cut my fair share of Acme and buttress threads. An Acme thread cut in four passes would, in my opinion, be only suitable for something like the screw for a sash cramp, where play between the screw and nut is desirable. To compare a hobby machinist to an industrial machinist is not a fair comparison, to a hobby machinist, time is not the over riding consideration, as he or she does it for the sheer pleasure and satisfaction of producing a machined component in his, or her spare time, a process that might be light years removed from his, or hers every day working life.

[Sub MandrelParticipant @submandrel]

There is a clear relationship between the horsepower of the lathe and the rate of metal removal. Big lathe=bigger cuts

Neil

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Production turners are a bit of an endangered species now but at the time I was talking about there were still many of them to be found in industry .These were fully skilled people who made large quantities of identical turned components using just their skills and ordinary lathes .

They were called production turners because that is literally what they did – make parts in volume production .

Because they basically did the same job over and over again for sometimes weeks the better ones became marvelously adept . This came about in part by simple familiarity but often over the first few off everything was optimised – blank size , work holding , speeds , feeds , tooling , different settings needed , measuring procedures and many other things , Some turners also fitted their lathes with home made devices to aid rapid production from dial gauge mounts , stop blocks and special size sllps down to chalk marks and mirrors .

One off's , small quantities and toolroom turning were usually done by other people .

There were also production millers with comparable skills .

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