A RETURN TO THE WORKSHOP 
PART 8
BY JOURNEYMAN

JULY

Since the end of June, things have moved on for us here in the Styx.  The middle of July brought our son’s wedding to the wonderful Emma in the village church where he has his dairy farm, A wonderful village wedding at the heart of the farming community. His farm is thriving and expanding, in contrast to the general perception of dairy farming being a loss making occupation.

The fine weather finally arrived at the end of July, and with the completion of all our commitments I finally got down to some regular model engineering.  I am currently working on Boxhill’s lubricator and it’s drive train, adopting the arrangement designed by my mentor in which the unit is located out of sight immediately in front of the cylinders, instead of dumped on the footplate with a non-authentic drive off the rear wheel crankpin as prescribed by Martin Evans. It’s very neat. 

I was able to use a technique for making it’s tank that I learned from my late father many years ago. His hobby was silversmithing and box making was one of the skills he learned. These were made from sheet metal, and to make clean and sharp corners he would score out v-shaped right angled grooves almost through the metal, using a special scraper made from an old file suitably hardened and ground, and then folded and soldered.

With careful marking out near perfect boxes can be made in this way. I used a sharp needle file for the job by doing the four sides in this way and then butt-soldering on the bottom. ( see photos ).


EARLY OCTOBER

With the lubricator in place, I entered “Boxhill’s” chassis in my Club Exhibition, no prizes, but not surprising in the light of the competition, including some superb aero engines.  I have now embarked on the boiler.  As we all know, the price of copper is stratospheric and seamless tube cosmic, so I decided to make the barrel and firebox outer wrapper from sheet which I had in stock, forming the seam from a butted and strapped joint.  This went well, and has been followed by the throat plate and I am now working on the firebox, for which I have just formed the flanged plates.  This has been greatly assisted by the loan of a set of the steel forming plates by my mentor. 

In the meantime, Mrs Journeyman and I went for a short break to Cornwall where I succeeded in breaking my ankle by treading on the edge of a concealed rut whilst strolling over the grassy sand at Porthtowan.  However, we did manage to have a good look at some of the mining remains in the area including the substantial harbour and tramway incline works at Portreath which was a major port in the mid 19th century for the import of coal, and export of metal ores, from and to South Wales, where the ore was smelted to save having to ship even more coal across to Cornwall. 

The history of the county’s metal mining is fascinating and there must be thousands of miles of unmapped shafts and galleries beneath the major centres such as St Just and Carnbrae.  The landscape tells its own tale with all manner of industrial ruins, engine houses, calcining chimneys, and what little is left of the works buildings of  great companies such as Harveys of Hayle, The Cornish Copper Company, and Holman Brothers in Camborne, who produced the machines and equipment for the industry both at home and abroad. If you ever find yourself down that way try and visit the Mining Museum at Geevor, and the restored winding engine at Levant, both spectacularly situated on the north Cornwall coast.

The seasons do not seem to be favouring our veg. garden for the last three years.  Ice, snow and  prolonged freezing conditions have blitzed our winter brassicas,  and this Spring’s dry and extended cold spell meant a poor start for everything, including the tomatoes in the greenhouse.  Global warming, probably, natural seasonal variation, also probably.  Maybe we should be giving attention to reducing emissions from our steam models; now there’s a thought for the future before we are regulated!

November looms and with it the short days and decline of work on ‘the estate’ giving more time for the workshop.  Boxhill’s fire box is coming on as the pain in the ankle recedes and I am able to do longer spells at the bench.  One of the things that has been occupying my attention  is the transition to cadmium free silver solder. 

I have spoken to one or two suppliers of the stuff and they all say that there is not much difference between it and the cadmium bearing alloys, the principle difference being that the melting ranges are greater and that great care must be taken to get the metal hot enough before applying the solder.  The man at Johnson Matthey was most helpful and arranged to send me some sample fluxes and alloys, one of which, Silverflo 20 has an upper melting point of  815°C. 

I decided to try it using the recommended Tenacity No.5 flux on the bar stay on the smokebox tube plate, as this is inside and would be at risk of falling off on subsequent heats to solder the plate and fire tubes in position in the barrel.  The solder ran beautifully at a bright red heat confirming it’s  flowing properties, so I now feel more confident to use cad-free on other joint.

I’m learning fast just how important it is to do everything accurately in this boilermaking lark, especially the soldered joints; too wide a gap, which isn’t much, and the solder just runs through and won’t fill, and too tight a gap and the solder won’t penetrate leaving a faulty joint with the possibility of future failure! 

I was once given a tip to help fix just the right gap.  If you put a centre pop into metal it raises a rim like a tiny volcano which can be used like a spacer, suitably filed down to the right height to give that 0.003”-0.005” gap.  However, this doesn’t happen to annealed copper, so instead I use a diamond-shaped graver to raise a small barb to do the same job, neat and simple.                      I have adopted the practice of holding the various bits together prior to soldering using 8BA phosphor bronze screws, another recommendation for my Mentor.  In this way I can see if the joints are close fitting without applying too much pressure, which is a risk with copper rivets when it comes to soldering, preventing the solder from penetrating properly.  I make them myself from 1/8” rod and cut the slot using a piercing saw, a bit time consuming and tedious but well worth the effort.


NOVEMBER

So that’s it so far. The rhubarb and currant bushes need mucking and I must catch up on the grass cutting that hasn’t been done due to the broken ankle, now much better.

Trimming the firebox tube plate.

Soldering the boiler barrel.

Notches.

The mechanical lubricator.

Mechanical lubricator installed-2.

Mechanical lubricator installed.

Mechanical lubricator and drive train.

Cutting the notches.

Model engineering in the Styx -

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