How big Are Your Chips

[Clive FosterParticipant @clivefoster55965]

Reminds me of the brochure for my Pratt & Whitney Model B 12 x 30 lathe which includes pictures of steel chips to illustrate its capabilities. My copy is a none too high resolution download so I cannot do pictures.

____

“Here are three chips, widely different, yet all cut on the same Model B Lathe.

At the left is a piece of "lace chip" 0.02” wide and almost 200 feet of unbroken length. The actual computed thickness of this chip is only 0.00011 but it did not break.

Below is one continuous ribbon chip 1” wide, about 0.001" thick and 196 feet long.

The third one, shown 3/4 actual size is a typical heavy steel chip picked up at random during a hogging demonstration.”

_____

By my estimates the hogging chip demo is something over 1" wide by more than 3/16 thick in a tight spiral about 2" diameter.

Being almost 80 years old, with considerable evidence of uncaring ownership, I think mine is no longer capable of producing the lace chip but its still able to accurately remove less than half a thou on diameter and take as heavy a cut as I care to deal with. Perhaps half the hogging demo size.

Clive

[Harry WilkesParticipant @harrywilkes58467]

Posted by Ian Johnson 1 on 25/01/2021 19:24:38:

Great photo! Not seen it before, any more info about it?

Looks quite modern to me, the guy on the left with his safety glasses, and the other guy with his winkle picker safety shoes!

IanJ

Sorry Ian i asked the member who submitted the photo but he doesn't have any info neither.

H

[OldironParticipant @oldiron]

Posted by Pete. on 25/01/2021 20:07:35:

Some of the people on this forum having sleepless nights over a man in his shed drilling a 3mm hole in a piece of metal would have an aneurysm if they saw what went on in that factory.

regards

[Oily RagParticipant @oilyrag]

Those chips probably came off one of these Mini lathes:-

or these lathes (love those exposed gears) :-

And then the inspector wanted an impression of the rifling at the forcing cone area!

"C'mon Ethel – time for yer tea break!"

Photographs from the COW (Coventry Ordnance Works) in the manufacture of 15" Dreadnought Gun Barrels. 1917.

Martin

[Nigel Graham 2Participant @nigelgraham2]

I like Ethel's suitably radiused and rifled Head-wear, Inspectors, Gun-Barrel.

Something the photos bring out is that gun-barrels like these were of laminated form, and I wonder how they coped with each tube sagging under its own weight between chuck and tailstock or steady.

Magnificent machining, despite the grim reality of the work-pieces' sole purpose. 'Tis said the elevation gears on the Bernard Lovell Telescope (Jodrell Bank) are spare warship gun-turret training gears.

Those lathes were probably purpose-built, but I wonder if anyone in this country now still has the machine-tools for work on similar scales.

I worked for a time in a small electronics company that employed two retired professional engineers a couple of days a week to perform some of the small but trickier metalworking tasks involved in our prototype and experimental contract work. These fully time-served gentlemen had previously risen to managerial levels elsewhere, but with us were now enjoying part-time, skilled craft-work back at the bench. One told me of his time with the UKAEA. He said some of the one-off machining on very large, very costly parts for things like experimental reactors, was so critical that it was not unknown for even very skilled, experienced machinists to become too frightened to take the finishing cuts. He quite often had to help some poor chap by verifying the measurements and settings, and standing by him to give moral support.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Nigel Graham 2 on 28/01/2021 22:18:15:

…

Those lathes were probably purpose-built, but I wonder if anyone in this country now still has the machine-tools for work on similar scales.

…

Sheffield Forgemaster's claimed in 2018 to have the UK's largest 5-axis Vertical Lathe (Big lathes are often vertical because long jobs bend if held horizontally.)

Weighing almost 250 tonnes, the BOST VTL is the largest and most capable 5 axis Vertical Turning Lathe in the UK and required the removal of 6,000 tonnes of earth and 3,400 tonnes of concrete to create a foundation. It has a maximum machining height of 4m, maximum swing diameter of 8.5m, table weight capacity of 100 tonnes…

Dave

[Ian Johnson 1Participant @ianjohnson1]

Posted by Oily Rag on 28/01/2021 21:39:53:

Those chips probably came off one of these Mini lathes:-

And then the inspector wanted an impression of the rifling at the forcing cone area!

Photographs from the COW (Coventry Ordnance Works) in the manufacture of 15" Dreadnought Gun Barrels. 1917.

Martin

I've operated big lathes with two tool posts, with hydraulic copiers, but that is just showing off with three toolposts!

IanJ

[duncan webster 1Participant @duncanwebster1]

I've seen a picture somewhere of a monster Crawford? Lathe with a headstock at each end and 2 tailstock in the middle so you could do 2 "short" jobs at the same time or lift off the tailstock and do one really long one

Edited By duncan webster on 29/01/2021 19:37:49

[Oily RagParticipant @oilyrag]

And here is Ethel at the Breech end:-

This clearly shows the staggered and stepped 'thread' for the breech block.

My father worked at this factory from 1913 as an office boy – he went on to be a turner/fitter and just missed being called up at the wars end as his foreman had the power to retain 'good men' – just working in the armaments industry was no guarantee of not being 'called up'.

He told me the chips that came off the three toolpost lathes used to fall with a resounding clang when they broke off, sometimes helped by a crowbar to break off.

Indeed the big naval gun barrels were laminated, the riffled inner sleeve was wound with steel hawser, then the outer sleeve was heated in a vertical 'oven pit' (with large gas rings on the walls every 5 feet apart). Then the inner was slid into the outer and allowed to cool. The inners were hardened in the same 'oven pits' but then quenched in whale oil tanks also let into the ground.

This works also produced the 9" howitzers, 6.5" canon and 5.5" howitzers used by the army on the western front.

The building is still there in Red Lane, last time I went into it the Oven Pits and Whale oil tanks were still there as well.

Martin

[Ex contributorParticipant @mgnbuk]

I've seen a picture somewhere of a monster Crawford? Lathe with a headstock at each end and 2 tailstock in the middle so you could do 2 "short" jobs at the same time or lift off the tailstock and do one really long one

The first customer service vist I did while at Broadbents was to VSEL at Barrow. In the bay next to the one our lathe was in there was a Craven Bros lathe of that configuration – headstock each end of the bed, two tailstocks & four saddles, probably around 4' centre height. I paced it out at around 110' between centres ! At the time it had a propeller shaft of around half the bed length in place. The prop shaft had been coated with GRP and was rotating slowly to stop the coating slumping as it cured.

I worked on site at a company working in the former DeVleig works at Red Lane – Merrill Engineering IIRC. They were rebuilding another Craven Bros machine, a large VTL for the old ROF Barnbow tank factory outside Leeds before it became Vickers – the company I worked for supplied the electrical panel & pendant for the machine. The company did a promotional video of the works Escort van being slowly rotated on the VTL table – I can't recall if the table was 14 or 18' diameter. The machine was used to turn the bearing seating face on the underside of tank turret castings – this was around 1984/5, so maybe Chieftains ? Turnings from that machine came off like car coil springs.

Nigel B.

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