John Day memoirs incomprehensible machinery

 

I have reached what should be the last couple of episodes of John Day’s memoirs which I’ve been following on and off for the past year. John Day was a premium apprentice in The Royal Arsenal in the 1930s; A premium apprentice was a school  academic highflyer 

 recruited to the Arsenal to be trained for a future in top management of some sort or another. I’ve been using extracts from autobiographical material which he gave to Greenwich Industrial History Society Newsletter in the early 2000s. In them he describes how he was continually moved from Department to Department with the perhaps a few months at each place at one time. His job was to learn how things were done and how the place functioned

The first place he mentions in the chunk of his text I’ve taken out this week to use is the ‘Light Gun Shop’. I have been unable to discover exactly where this was on the Arsenal site, or indeed to find out very much about what it did at all. I appreciate that ‘light guns’ must have been made in vast numbers which implies it might have been a big building - but I can’t see it on the plan or find out anything about it. Or, more likely, I can’t see it on the plan for looking.

In connection with this Department, John commented that ‘Guns, particularly in the breech, use a lot of odd, large size countersunk screws’. These were not popular with the regular workers ‘as they did not rate well in the piecework stakes’ and were left for the apprentices to deal with. However, John says, ‘but the saving grace was that an apprentice had the right to refuse to make more than twenty three of any one thing’ and concludes ‘It was realised that they were there to learn and not to take part in production’.

One problem with some bits of John’s memoirs is that he talks about various machine tools apparently thinking that we all know what he is talking about.  Most men these days work in other fields – whereas in the 1930s most boys would go into productive industry- and so now have no idea what he means’.  So, he describes work in the ‘Light Gun Shop’ using with a ‘number of Morse taper sleeves of the larger sizes’  - can someone explain what this is or was ??   ‘It cannot be something he has learnt to make himself on site since ’Morse’ is a trade name. He says it meant ‘that the internal taper hole was longer than the travel of the lathe top slide .... apprentice’s lathes did not have the luxury of taper turning attachments.’  So apprentices in the Arsenal only got to use old and outdated equipment, then?

John says he complained to the foreman about this and “he knocked me out of the way, did one, and then said you will do the ****** rest ..... another lesson”.

Next, John spent six months in the Mechanical Engineering Department’s drawing office. He then went out ‘on my own’ doing drawings of machine tools and details of their installation.

One such was a large vertical slotting machine to be installed in the Light Gun shop - there were already three such machines in place there.  A vertical slotting machine (also called a ‘vertical shaper’ or ‘slotter’) is used for cutting internal features like keyways, spines, grooves, and complex metal profiles. Unlike a horizontal shaper, its single-point cutting tool moves vertically up and down to shave material away incrementally from the piece being worked on.

It seemed to John that it would be a good idea if the new machine should be installed in line with the existing three - so he did the drawing accordingly. Several weeks later he saw the new slotter in place but ’it was two or three feet in-front of the older ones - not where I had wanted it put’ .  Then ’the ganger’ explained that when they put it where John had suggested ‘the counterweight at the back had fouled a piece of shafting’ so they had moved it forward. ‘He said that he had seen my name on the drawing and, as my father was the manager of the department and the gang had had double time for moving it, it seemed silly to mention it’.

Another ‘interesting bit of plant layout that came my way was the installation of an autofrettage plant’. He explained that ‘this is a process which increases the strength of a gun barrel by subjecting it, internally, to a hydraulic pressure which exceeds the elastic limit of the metal’. It consisted of two bed plates, one with the pressure generator while the other was just a support and a stopper for the other end.

Another description of an autofrettage plant is ‘an industrial facility or specialised testing rig used to pre-stress thick-walled cylinders. By applying extreme internal hydraulic pressure (sometimes up to 15,000 bar), it forces the inner metal to yield. When pressure is released, the outer elastic metal compresses the inner wall, creating residual compressive stress that drastically increases the component's fatigue life‘.

As the new machine had two lengths of barrel to be processed, John did a drawing showing two sets of studs cemented into the floor – done so that the other bed plate could be picked up by the crane and set down over the appropriate studs. The chief draughtsman looked at his drawing and said “fine, sooner or later somebody will trip over the spare studs, put in a suggestion, get £5 and they will be sawn off”.

John next describes a session in the North Mill un-mothballing the gun lathes. He says it was a ‘mucky job since they were coated in a thick oily varnish that had to scraped off’and had been untouched twenty years and had had time to harden out. He commented ‘at least we were beginning to get ready for World War II in 1938!’

Next he was at ‘The Tinman’s Shop’ – another department near the Plumstead Gate. He said ‘it made a change. One job there was setting presses for stamping out ammunition containers.  He explained: ‘The top and bottom tools had to be very accurately set, both for position and material thickness, because when the presses ran there was quite a large force involved.‘

The presses worked with a single revolution clutch which had a latch coupling the big flywheel to the crankshaft - and it was controlled with a pedal.  When this was depressed the clutch engaged but releasing the  pedal, even momentarily, meant that the flywheel did at least two revolutions for one of the crank.

Unfortunately some of the operatives working this machine thought they were fast feeders – but if they were actually slow it resulted in a jam-up because the second piece of metal arrived before the first piece had cleared. John was given the job of sorting this out. He says ‘there was a way to rectify the tools by gently peening (hammering) the edges and then using an oil stone to restore the proper clearance.’

Throughout this narrative John’s involvement in various workplaces is mainly with a relatively small number of skilled staff - of which of he would have been counted as one. The vast numbers who worked in the Arseal presumably, as part of their daily lives, also only relate to those immediately around them. We should look at a plan with all the various workshops and factory areas labelled  - and there is such map on the Royal Arsenal History web site. It will show just how many such workplaces there were and how close together they all were to each otherb - hundreds of different buildings and facilities are shown.

On site there were a number of facilities available to all workers - however badly managed they may been. John talks about the canteen facilities and also the rather primitive medical services available.

John said that as far as he could remember there were four canteens for the use of the workforce on the Arsenal site. They all reeked of a strange mixture of boiling fat, cabbage and cheap soap - and he kept out of them - but they were well supported during the day for tea as well as during the official lunch hour.

The surgery was presided over by “Septic Sam”. As now, all injuries had to be reported and sent to the surgery but such was the treatment meted out that small injuries were kept quiet. John went once and had a memory of a mid - Victorian standard of equipment and hygiene. The surgery backed onto the boundary wall and a couple of hundred yards from the main gate nearby was the apprentices club. It’s main attribute was a table tennis table which was heavily used lunch times and evenings.