Whats on your 2mm Work bench

[Ian Smith]

Here's the result.  Phone camera hasn't focused very well on the finial, I'm afraid!  Certainly takes the 'solid' look off it.

20ft signal finial.jpg

 

This photo also shows up the rather too opaque red spectacle, but the green one looks OK.

Jim

Jim,

On the only signal that I've so far made I filled the spectacles with a small amount of "Canopy Glue" (which dries clear).  Once dry I coloured the "glasses" with Staedler permanent fine marker pens - the green blue being just that coloured blue and once dry over coloured with a green (unfortunately I can't remember with shades of red, blue or green I used they are all in a comprehensive set of my daughters!)

 

Below are a couple of images which hopefully show the "see-throughness" of the glasses :

 

Ian

 

PS

Unlike Mr Carlson, my signal lamp is just a simple turning and does not present a pretty light like the ones on St Ruth do (or do when wired up to do so, we are still working on general illumination of the St Ruth environs)

[Caley Jim]

 

.....On the only signal that I've so far made I filled the spectacles with a small amount of "Canopy Glue" (which dries clear).  .......

 

Unlike Mr Carlson, my signal lamp is just a simple turning and does not present a pretty light like the ones on St Ruth do (or do when wired up to do so, we are still working on general illumination of the St Ruth environs)

As I said in an earlier post, I experimented with the red glass by mixing a spot of red paint into some Clearfix, with the result shown (probably too much paint). For the green glass I used the Clearfix as intended and washed it with then green paint - Humbrol Multi unit stock green (don't ask!!).  This was both easier and gave a much better result, as per your 'canopy glue'.

 

Likewise my lamps are simple turning in the minidrill.

 

Jim

[CF MRC]

A cast backhead.

As intimated in previous posts, I intended to make a cast backhead for 2003. So the pattern was made from styrene - a little thickened in some areas to allow for metal flow. The details were broadly derived from an A4 backhead.

 

This pattern was sprued with wax into the bottom corner and mounted onto a casting cone. The spherical swelling on the sprue acts as a metal reservoir close to the pattern. The casting ring is lined with a thick card-like material to allow swelling of the investment (not sure why these images are horizontal). The vacuum-mixed gypsum investment was poured onto the pattern in the casting ring, making sure that there were no air bubbles. Once set, the investment is taken up to a high temperature (700 dec C) that burns out the plastic and wax, leaving a space for the incoming molten metal. At the same time, the investment expands to compensate for the shrinkage of the molten metal as it freezes.

 

The casting was made using an induction-heated vacuum casting machine with 1030 deg C melting point alloy: "Phantom Metall NF". Once cool, the student's alloy casting (brass) was divested and then bead blasted to remove the remnants of investment. The casting was then fettled and bolted into the cab. It needs the fire screens fitting to protect the driver and fireman's legs. At least they won't have to worry about a dangerous drive shaft on this engine!

 

Tim

 

(P.S. I expect this has stimulated a few of Jim's memories from his dental undergraduate education)

Edited January 30, 2016 by CF MRC

[Southernboy]

Absolutely wonderful stuff. I marvel at this sort of work.

[Caley Jim]

(P.S. I expect this has stimulated a few of Jim's memories from his dental undergraduate education)

I did take the precaution of keeping a tin of investment when I retired, but haven't had the occasion to use it yet.  I do not, however, have access to an induction casting machine.  Might have to resort to the ancient technique of centrifugal casting with a bit of string!!

 

Meanwhile the 40ft signal with co-acting arms is making slow but steady progress.  The fret was on the under-etched side, so the root canal files have been busy opening out the small holes!

 

Jim

[CF MRC]

You could always use a half potato for driving the molten alloy into the investment cavity, Jim. Bits of string could be risky!

 

Tim

Edited January 31, 2016 by CF MRC

[CF MRC]

Two crossheads & pistons

These little devils were quite fiddly. I made the first one on the left hand side by dead reckoning and serendipity. The second one was, of course, much easier as I knew what was needed; so I photographed it's construction

 

The slipper and socket for the piston rear end was cut out of sheet steel with a bit of excess material for filing back later. This was then bent up with the piston socket going backwards and the slipper folding forwards. The metal was scored with a slitting file to ensure that it bent predictably. The piston was made from a broken twist drill (I have plenty from this project!) and the socket was augmented by a small length of syringe needle towards the front.

 

The whole lot was then silver soldered up. Following the article on silver soldering in the latest MRJ I got some 'Silver Solder Paste Easy 15gm Syringe' from Palmers metals. This is really much easier than separate flux and solder for these very small jobs. The long tag hanging down was subsequently scored to allow it to bend right back on itself to form the basis of the arm which will be surrounded by the forked union link. This was then silver soldered again, to make the whole assembly very strong. Finally, the two holes for the little end and the union link were drilled.

 

At the moment, the crossheads can slip back towards the wheels, but the connecting rod will hold them out, as will the union link and combination lever. The connecting rod will have the little end pin silver soldered to it, pass through the crosshead, and then the big round boss and castle nut will be represented by a piece of syringe needle and the pin slightly poking through. Not quite prototypical, but I don't think I'll loose any sleep over it.

 

Tim

 

(P.S. Do you like my new avatar? LNER publicity sticker from the era)

[Caley Jim]

You could always use a half potato for driving the molten alloy into the investment cavity, Jim. Bits of string could be risky!

 

The casting machine in the students lab in Glasgow in the late '60's was a fearsome beast operated by compressed air.  A single knob controlled a rising platform and when the casting ring made contact with the top you had to quickly turn the knob hard round to redirect the compressed air to a nozzle in the top which forced the molten metal into the mould.  If you got the timing of that last twist wrong, half the lab got showered in molten metal!

 

Jim

[CF MRC]

At Guy's, as students, we had centrifugal casting machines that were wound up: effectively clockwork powered. They required a choreographed action of placing the hot casting ring in the arm, heating the gold in the crucible with a gas torch and letting go the centrifugal arm at the correct moment. We did our phantom head course with real gold and it was quite easy to harvest splattered gold from around the casting machine, if you followed the less savvy students who put the ring in back to front. In this way I collected enough material for my first gold safety valve. Students nowadays don't have half as much fun!

 

Tim

Edited January 31, 2016 by CF MRC

[Kylestrome]

This is turning into a dentists blog – not that I'm complaining, but I thought we 2millers are supposed to be watchmakers!

 

BTW, can you explain what half a potato has to do with hot metal casting? 

[CF MRC]

Sorry for the dental stuff, I do use a lot of watchmaking stuff as well.

 

The technique for casting with a potato is that the alloy is heated in the cone of the investment ring until molten. A wet half potato is then firmly placed on top. The flash steam from the potato drives the metal into the mould space. Other techniques that used to be used are a stirrup and chain (a better engineered version of Jim's string), swinging the casting ring in the stirrup around by hand, once the metal is molten.

 

Tim

[Caley Jim]

As a diversion from the student reminiscences of Tim and i, I present for your delectation Sauchenford down home, a 40ft Stevens and Son lattice post signal with CR style arms.  The height is necessitated by the presence of a road over-bridge.  The gallery to allow servicing of the lamp of the repeater arm is based on a photo in Jim Summer's book or CR signalling showing a similar post with a lower calling-on arm.

 

 

Jim

[queensquare]

This is turning into a dentists blog – not that I'm complaining, but I thought we 2millers are supposed to be watchmakers!

 

BTW, can you explain what half a potato has to do with hot metal casting?

This 2mm modeller is more of a blacksmith than a watchmaker but still thoroughly enjoying the thread - both big engines from the east and signals from the far north - and I'm terrified of dentists usually! I do know a bit about spuds mind, but it's a bit early in the year for that :-))

 

Jerry

Edited February 2, 2016 by queensquare

[CF MRC]

The connecting rods for Lord President are, of course, tapered and fluted. I had thought about milling them out, but the taper makes life tricky. In the end I simply made a skinny rod and then silver soldered two sides to it to make the webbed casting. These additions were then filed back until they almost disappeared.

 

The little end pin was initially a drill shank silver soldered in place. I subsequently learnt that this would not accept soft solder for the securing collar, so it was replaced with a bit of watchmakers pivot steel. Clearances are tight, but seem to be working out OK. Looking at the unkind photo, I will take the top web off, thin the rod down and soft solder a new web in place.

 

Tim

Edited February 2, 2016 by CF MRC

[garethashenden]

How thick are your rods Tim? I'm thinking I made mine too thin...

[CF MRC]

About 0.5 mm at the thick end. I always start off thick and thin down where required. It gives a good appearance of mass in the bearings.

 

Tim

Edited February 2, 2016 by CF MRC

[JohnBS]

About 0.5 mm at the thick end. I always start off thick and thin down where required. It gives a good appearance of mass in the bearings.

Tim

Tim,

Great to see that you now have plenty of time for modelling AND for posting. The posts are really inspiring and helpful. I must admit to using your technique for connecting rods, except that I cheat and use nickel silver and soft solder - much easier to clean up and usually quite strong enough. Luckily, GWR coupling rods have no fluting, only bosses and a dummy hinge to worry about, and of course, no external Walschaertes.

Like your new atavar but Il Presidente does look a bit like something that comes out of the front end of a 0.50" Browning.

Very best wishes,

John

[2mmMark]

Tonight's mystery object from my workbench

 

 

Tim will know what this is but it might puzzle others. Details will be revealed in due course.

 

Mark

[CF MRC]

As promised, I modified the slightly obese connecting rod. Happier now. The next one will be better.

 

Tim

[Caley Jim]

Tonight's mystery object from my workbench

 

 

If this had been posted by Tim I would have said it was a jig for drilling the holes in Lord President for the boiler handrail knobs.  Otherwise.....

 

Puzzled of Biggar

[2mmMark]

And the answer is, a turnout for use in the Copenhagen Fields fiddle yard. As people will know, we use solid nickel & brass strip track behind the scenes. Fabricating a turnout from this would be quite labourious.  Tim sent me a couple of turnout plans, so I decided to lay plain code 40 strip rail straight onto a single sheet of PCB. This should give us a robust turnout for the fiddle yard. It still needs gapping but that's a simple job.

 

 

 

Assembly proved much quicker than a conventionally sleepered turnout. I used the 2mm Assocation templates intended for the turnout soldering jig and simply screwed them down to the PCB on a length of wood.  The tiebar is very chunky, again for robustness.  I've also gone for extended check & wing rails in a quest for reliable running.

 

Mark

 

 

[Caley Jim]

........ and signals from the far north - 

I wouldn't say they were from the FAR north - some modellers of the Highland Railway would challenge you on that!  But then you folk in the far south consider Manchester to be 'the north' and equivalent to 'pith helmet' country!!

 

Jim (note where Biggar is in my location)

[queensquare]

I wouldn't say they were from the FAR north - some modellers of the Highland Railway would challenge you on that!  But then you folk in the far south consider Manchester to be 'the north' and equivalent to 'pith helmet' country!!

 

Jim (note where Biggar is in my location)

The North starts the other side of the M4, Swindon is a frontier town!! :-))

 

The Cornish only recognise two parts to the country, Cornwall and 'up country' . I worked with an old boy when I lived in Cornwall who had only been 'up country' once, when he went to Egypt via Plymouth during the war. They brought him back to Plymouth at the end of hostilities and he went back to Lanner. That was as Far East as he went in his life.

 

Jerry

[2mmMark]

I was once assigned to do some work at Ronaldsway in the Isle of Man with some colleagues from Manx Airways. We went for lunch to The Viking pub in Castletown. There was some discussion about the wisdom of heading north to Ramsey for some shopping. I got the impression that in my colleagues mental map of the island, "Here Be Dragons" was written north of Douglas.

[mike morley]

I was once in a lovely little tea room in Sulby on the Isle of Man, absently eavesdropping on the conversation going on in the kitchen, and one of the girls announced that a friend of hers was moving " . . . to Douglas!!!!" in the awed tones one might use to announce a move to Outer Mongolia.

Edited February 4, 2016 by mike morley