FITTINGS

I haven't been able to copy the fullsize for the edges of the cab. The edges are finished with T section along the bunker and round the cab doorways. The top part merges into the joining part of the escutcheons. I've tried to copy the style but it doesn't look as good. I don't have a taper turning attachment on my lathe to turn the columns and had to manage with the top slide at an angle of about a half a degree and keep on shifting along. It's not too bad.

I stripped all the valve gear down on both sides and re-set the timing, partly because reducing the width meant a new reach rod for the reverser and partly to paint those hard to get at pieces which always go rusty. I also had to alter the motion plates and had some difficulty re-fitting the steps. At the same time I painted the footplates, again to prevent rusting when underneath the side tanks.

SAFETY VALVES

I've made the safety valves while I'm waiting for the boiler (he's gone to Australia for Christmas!!) Nothing special about them; I've tried to make them as close to scale as possible. They are a little oversize. One is a basic type and the other is a Ross Pop type. Just one of those things I like to do although this time, I've not made them so that the valve seat can be got at.

Being the holiday period, I've not done quite so much. I have spent some time with my grandson on his new loco which is Don Young's 'TUG' an 0-4-0 railmotor which he's taken over from somebody who's fallen by the wayside so to speak. Certainly much more interesting for him than a Gauge one. At least he'll be able to drive it on a proper track. No doubt I'll have to find the money for the boiler!

1 January 2008

LUBRICATOR

I'm continuing with all the fittings until I hear about the boiler. So I've been playing with my CNC mill to mill the slots and holes for the hydrostatic lubricator. The glass sits in a trough top and bottom which is quite tricky to mill especially when it's a double, even with a rotary table. It's a simple job with the CNC and the whole thing from drawing to cutting out took about an hour. The beauty of this is that the holes for the corner uprights are exactly placed.




There are quite a few bits to make as can be seen in the photo but they are all straight forward without any problems.I prefer this type of lubricator as it gives perfect control over the quantities of oil delivered. The disadvantage is that you need to keep an eye on it as a drop in pressure will reduce the quantity of oil sent. The mechanical type can of course, be left to get on with it and doesn't deliver oil when stationary, which is fine providing the setting is correct. I've seen a lot of drivers and passengers with spots of oil all over their faces and clothes!!



DRIVER'S STEAM BRAKE VALVE


This is the first time I've made a steam brake. I've looked at various brake valve designs and most are complicated with double cams. Then I came across this design by Don Young which is very simple in comparison. Placing the various holes accurately probably needed a rotary table. I also didn't have a lump of brass bar big enough, so once again I did everything with my little CNC set up. I did have a piece of flat brass thick enough which was suitable. The end result being very neat and of course spot on.


This next picture shows the simple valve on the inside without the sealing covering cap on. The valve is in the off position. The last picture is the finished job but without any bracket fitted as I'm not sure where it will be in the cab. I want it to be ergonomically right, i.e. with the brake handle pulled towards the driver to put the brakes on. So that I wouldn't make a mistake when piping up, I've cut a different thread for the steam inlet nipple. One mistake I made in that I didn't leave enough space on the outer edge for the nuts and washers, so that they overhang. It looked terrible so I ended up making a complete new outer!

I went to see the boiler man. His main problem is putting in the tight bends at the top of the firebox wrapper as it's a 90 degree bend. He had a very ancient bending machine worked by hand and even with two pulling on the gear, it still wouldn't bend. Finally it cracked. The machine weighed 4 tons and was enormous and of World War one vintage. He's finally replaced it with a 50 ton hydraulic press which he assures me will do the job with ease.



24 January 2008

WATER GAUGE

I've always made my gauges with three taps but I'm told that if a glass does break, then there is very little chance of getting near enough to turn the taps off! However,since I drive with a leather glove on, then I might. I've also made the taps of the tapered variety and had endless problems getting them to seal, so this time I'm using a different method. The blowdown is an ordinary screw down valve and the other two are straight with an 'O' ring on either side. These are clamped down hard but can still be turned. In an emergency, when they are turned, the steam might leak passed slightly but that wouldn't matter.

I managed to buy a short length of bronze bar which I machined into square section after I'd bored and tapped where necessary. Everything else is stainless, even the nuts with just the endcaps in brass. I am going to fit two gauges as per full size, so there was a lot of work in making so many pieces,as can be seen in the first picture. I'm not sure whether to paint the bodies as last time the red paints which I tried, both failed to stand the heat and ended with a burnt look. I think maybe I'll use the same paint as I use on the smokebox which of course will be black not red. I could have made the piece which fits into the boiler as part of the bronze body but, having sheared one off on the last engine, as I tried to stop a leak by tightening, I've made the threaded extensions in stainless steel too with a brass lock nut. I still have to make a suitable handle.

VACUUM BRAKE & EJECTOR

I find ejectors quite easy to make once I'd made the two sizes of 'D' bits which are at 12 and 24 degrees. The only tricky bit is drilling the smallest hole which is 0.6mm diameter. Careful machining to length of the two jets is necessary so that the gap between is correct (0.8mm). When I tested it on air with my small bench compressor it pulled 17" at 60psi and 12" at 38psi. This latter being the limiting valve setting on our carriages. 60 psi is the maximum I could get on the compressor. There's not a lot of difference when using steam. Any lower pressure and the brakes start to come on.

The actual brake valve is also quite simple, although a rotary table or CNC is needed to cut a semi-circular slot on one of the faces. Everything else is just holes to line up. I cut mine from brass flat with the CNC. When finished, the whole thing makes quite a neat job which is easily mounted by bolting a bracket to the back as there's plenty of room to tap a couple of threads.

WHISTLE & VALVE

I've tried to copy the full size version as far as possible, but scaling the whistle itself would make it too small. I've made quite a few different types at one time but this is an organ type as per full size. I discovered some time ago that if you can blow the whistle using your mouth, then the chances are that on steam it will blow loads of harmonics and you have to let only a small amount of steam through to get the right note. This one blows a good note on air but blowing hard with the mouth barely produces a note. It's all down to the space around the plug.

I've had a lot of trouble getting the valve right. In the end I made it as a globe valve would be. It will be operated by a cord and be positioned on top of the steam dome next to the safety valves.

There's not much more I can do until I have the boiler, but there is quite a lot to do on the Romulant as the full boiler test is on 16th March. A few steam leaks where packing needs replacing, the water gauge needs attention and I must clean all clacks, injectors etc. Just a general service really.

21 February 2008

MANIFOLD

There's a lot of work in making the manifold. I could have had a casting made but decided that there was too much time wasted in making a pattern and then waiting for the casting. As I had a few odd nub ends of bronze, I made the whole thing out of these. It was quite tricky to hold parts together and at the same time not melt the solder in earlier joints. I made up a rose cutter to spot cut to fit the taps into the main part.The steam is collected from the boiler via a banjo coupling, with a stainless steel bolt with a hollow centre. The stainless is 5/8" diameter which is too small for the boiler specification which I made as 3/8 BSP. 3/8 BSP has a diameter of 0.64 something which is not a convenient size of steel bar. The boiler maker didn't have any other taps so he's leaving the bush blank for me to cut my own thread.

Another good reason for not using BSP is that I can't cut 19 tpi on my lathe gearbox. I've been told by those who are more expert than I, that the BSF thread is as near perfect as possible, so I've gone down that road. A 5/8 BSF is 14 tpi which I can cut. The top of the bolt I threaded 26 tpi and made a dome nut to fit. This I fitted with a brass ring and silver soldered the lot together. The brass doesn't come into contact with the steam, as the hollow centre stops short at the top. This ring clamps on to an 'O' ring. The complete unit has a spacer underneath to give clearance for piping up and each joint has an 'O' ring to seal.



7 April 2008

HOME . NEXT . BACK