27/02/2022

I've added another couple of locos to the collection recently and this is one of them. It's an LBSC designed Southern Maid which is a simple 0-6-0 tender loco with slip eccentric valve gear. My friend Dennis Ede built one many years ago and we spent many happy hours running the wheels off his!

This one appeared on Ebay looking very sorry for itself as it had obviously been sat in a wet shed for a number of years, The price was perhaps a bit more than I wanted to pay for such a loco but it was complete apart from half of the cab which was missing and the cab roof. It looked as though it had possibilites so I bought it. One thing that really interested me in this particular loco was that it had Averill cylinders with the one piece steam chest between the frames and this version doesn't seem to be as common as the version with conventional slide valve cylinders.

Unfortunately, I forgot to take some photos of the loco before I took it all to pieces for cleaning and painting, but the Ebay seller kindly agreed that I could use some of his photos from the listing.

I was pleasantly surprised when it arrived. It wasn't anything like as bad as it looks in the photos. The majority of the rust is on the wheels and the frames and it should all clean up fine. I think that the pressure gauge will have to go as it's a little large for this loco! The workmanship is reasonable but there are one or two things that I will tidy up e.g. the coupling rods, before reassembly. Judging by the soot in the smokebox it has done a fair bit of running which is a good sign and it hasn't been a mantlepiece model like some.

I have got another Southern Maid that is in much better condition than this but unfortunately it has obviously been dismantled at some point and has lost the wheels, cylinders and the valve gear. I have already bought all the replacement castings but I don't know when I will get around to that one. That will be interesting as it has been fitted with full Stephenson's valve gear rather than the plain slip eccentric.

I decided to have a break from Green Arrow, especially as I am waiting for some tin plated steel to arrive for the new boiler cladding, so I made a detour onto this locomotive. Hopefully, this one will be a quick fix (famous last words!). I don't intend to spend too much time on it. It will be a case of clean it up, give it a coat of paint and then run it.

The loco has now been completely stripped down and I'm in the process of painting the wheels and the frames. I'm also looking at the boiler and testing it.

The boiler looks quite well made and apart from a leak from the dome cover and a slight leak from the screwdown regulator, it held 160psi with no problem. However, I noticed that the firebox crown had bulged and I wasn't sure whether it was already like that or if it had happened during my test. That was worrying but I decided to tap it back into shape and test it again. This time there was no sign of any bulging and I think that maybe it happened on the initial test when the boiler was built or perhaps sometime during it's running life. Anyway, it seems to be fine now.

I decided to remove the dome cover to address the leak from the gasket and that was fun! The dome cover was held with 7BA steel nuts on brass studs and only one nut came off. The others sheared all the studs off instead! When I got the dome cover off it was obvious that the brass studs had been soft soldered into the dome bush. Brass is not really good enough for this application and I wanted to replace them with 316 stainless studs.

The only way to get the old studs out was to heat up the dome bush and hope that the studs would then unscrew. Two did but the others refused to come out and sheared off again. The only way was to drill them out and retap the holes.

Fortunately, I could bolt the dome cover, which is also the safety valve, back onto the bush with two screws and then use the cover as a guide to drill out the four broken studs. The boiler was very carefully held in the mill vice to hold it firmly with the top of the dome bush horizontal. It was then an easy matter to drill out the offending studs.

Drilling out the old studs

I decided to increase the size of the new studs to 6BA as the original threaded holes where the two studs had come out seemed a bit loose for 7BA so the dome bush was drilled and tapped to 6BA. The dome will be held on with brass nuts so they shouldn't seize again.

The new studs were made from 316 stainless and threaded with the tailstock die holder. I could have made life easier by just making some threaded rod and cutting it into bits but I decided to do it properly!

The new stainless studs

23/03/2022

I finished painting the frames and wheels and then fitted the wheels and the coupling rods after cleaning them up.

I wanted to put the loco on the N25GA stand at the Midlands Garden Rail Show as we were doing a Southern Railways theme so I hurredly fitted the cylinders, running boards, the boiler and the cab to make it presentable. The tender was left 'as found' as I didn't have time to do anything with that. It didn't look too bad!

I did have to quickly make up the missing half of the cab. That was a case of bending a suitable piece of brass sheet and then cutting out the profile after bending. I thought it was easier to shape the cab after bending as that meant the position of the bend wasn't too critical. Strips of brass were then bent up and soft soldered on to make the mounting angle at the base and the angle at the top that the roof will fasten to.

The most fiddly bit was shaping the profile to fit around the boiler but I think I got it closer than the profile on the existing half. If I do decide to fit boiler cladding then that will cover up any slight gaps.

I also stripped the paint off the boiler and cleaned it up a bit. It looks quite well made and shouldn't have any problems passing the official hydraulic test. I'll stamp it with a number before taking it for the test.

After the show, the loco was stripped down again to work on the valves and the valve gear. This hadn't been fitted for the show.

The ports in the cylinders were a little rough and had a few litle nicks in the edges so I took a skim off the port faces and cleaned up the edges of the steam ports with a 2mm endmill. I think the ports had been cut by drilling a row of holes and then opening up the holes to a slot using a small chisel. Whoever did them made a reasonable job of it and I only had to take a few thou of the edges to make them dead straight. I didn't bother with the exhaust ports as they don't take any part in the valve timing and are just a hole to let the exhaust steam escape.

The valves were very rough though so I decided to make new ones from blocks of gunmetal machined from slices of bar. They didn't really match the existing ports and certainly didn't now that I had remachined the ports.

Each set of ports was carefully measured up and the new valves machined to match each cylinder and then stamped to make sure they went on the right side.

The original valve rods were made from brass rod so I replaced those with stainless ones. The fork ends were held onto the rods by a 7BA screw so on the new rods I drilled a dimple in the rod and replaced the screws with socket head grub screws. They should hold the forks a bit more securely. I will also open up the holes in the fork ends to take larger pins where the eccentric rods connect. The original pins are only 0.0625" diameter and I can see those wearing very quickly. One of the original pins was just a bent bit of wire so the original pin must have fallen out at some time.

11/04/2022

Before I fitted the valve rods and the valves back into the cylinders I realised that I hadn't milled a slot in the valves to take the valve rod so that was quickly done. The valve rods were fitted into the valve chest and the valves and driving nuts fitted. It was then found that it was impossible to rotate the valve rods to adjust the valves as the corners of the square forks on the ends of the rods wouldn't clear the horns for the front axle. Heaven knows how the valves were adjusted before? I had to remove the rods again, put them in a collet in the lathe and turn down the outside of the forks to remove the square corners. This gave sufficient clearance from the horns for the forks to be rotated.

I had made two new larger diameter pivot pins to go through the forks and the ends of the eccentric rods which had a threaded end to take a nut to hold them in place. I now couldn't use them as there was not enough clearance between the fork and the horn for the nut. I am going to have to come up with another method of holding the pins in. They have to be easily removable so that the forks can be rotated for valve setting.

I decided to make the PTFE piston rings next so that I could put the cylinders back together. These were machined from 25mm plain PTFE rod exactly the same as those for Green Arrow etc. I made the outside diameter of the rings 0.020" larger than the cylinder bore and the inside diameter of the rings 0.030" larger than the diameter of the bottom of the groove in the piston. Rings were parted off and then sanded to reduce the thickness until two rings were an easy fit in the groove. A section was then cut out of the ring to give about a 0.020" gap when the ring was tried in the bore.

I'm still experimenting with PTFE rings but none of the dimensions seem to be critical. So long as the outside diameter is a bit larger than the bore to give the ring some spring against the bore, there's room for the ring to expand inwards when it's fitted and there's a gap to allow radial expansion then they seem to work fine.

The pistons were next fitted to the cylinders and the end covers bolted in place with thick brown paper gaskets. When I came to fit the rear covers I noticed that the bolts didn't sit down flat onto the cover as there was a turned ridge all the way around the boss that fouled the bolt heads. To get around that I put the cylinder in the mill and machined a slight counterbore to each bolt hole with a 3/16" endmill after lining it up with a drill in the mill chuck.

I then gave the cylinders a coat of the satin black smokebox paint.

To be continued

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