Post by mbrown on May 3, 2020 18:00:37 GMT
After completing my fabricated cylinders (see the separate thread) I said I would start a new thread for the loco build itself. Although I have already introduced the project, this new thread is likely to run for some time, so maybe a more detailed description is in order at this stage.
All my models are built for 2.5" gauge and represent 2' gauge prototypes. The reason for this is largely accidental - I started model engineering at the age of 13 when someone gave me drawings for LBSC's Southern Maid in 2.5"g, and eventually a model emerged, rather unlike Southern Maid, which managed to stagger up and down a short end to end track. Then came university, various jobs and further training until, at the end of the 1970s, I at last had a house and enough money to resume model engineering. I only had a very small lathe (a Centrix Micro - about the size of an Adept - later upgraded to a 2.5" EW) but I did have a spare set of 2.5" g cylinders and a strong enthusiasm for the narrow gauge, so a loco duly took shape and went very well indeed. Two others followed over the years, culminating in my Burma Mines loco in the avatar picture, completed in 2018.
My new project is a 600mm gauge 0-8-0 built in 1934 by Orenstein and Koppel for the Mecklenburg Pommersche Schmalspurbahn. It was one of three, but two were sent to the USSR after the War as reparations and promptly disappeared. The survivor became 99 3462 of the Deutsche Reichsbahn (E Germany) and remained in service until the line closed in 1969. She was then bought for possible use on the Vale of Rheidol and was stored for some years at Boston Lodge on the Ffestiniog. But eventually, she returned to Germany as part of the collection of Herr Walter Seidensticker who financed a major rebuild for service, initially, on the Kleinbahn Muhlenstroth at Gutersloh. Indeed, she is back there now, having had about 10 years on the German-Polish border at the Waldeisenbahn Muskau where she could get a decent run on a very fine railway. Apparently the boiler is now near the end of its ticket and so her future is uncertain. I visited the WEM last June to see her and take measurements and photos from which I am attempting to build the model.
Anyway, here she is in DR times.
99 3462 (3) by malcolm brown, on Flickr
The rebuild simplified a lot of the pipework and valves fitted by the DR, and a later overhaul certainly changed some of the boiler fittings, so I have an interesting task ahead to decide which era to model.... Here she is outside the shed at Weiswasser on the WEM, decked out for a special occasion.
ok_12518_60 by malcolm brown, on Flickr
That is probably enough introduction.
Now that the rather complicated cylinders have been completed, the next stages of construction are pretty conventional. I got to grips with 2D CAD over Christmas and have already received the frames and many other components from Malcolm High at Model Engineer's Laser, with another batch of drawings about to be sent off to him. This is the first time I have used CAD and laser cutting on a model and, having decried it as "cheating" in the days when I couldn't hack it myself, I am definitely coming round to the idea!
The first serious work, however, has been on the wheels. Last weekend, I did the tender wheels from some old disc wheel castings I had lying around for years. Unfortunately, one of the flanges has been fettled very aggressively, meaning that the overall diameter had to be a bit under size. But the wheels on the prototype are turned regularly, as the photo below proves, and will by now be somewhat down on the designed diameter, so I am content with "turned" wheels!
1509215_480148415423528_1924396876_n by malcolm brown, on Flickr
The small hole in the disc wheel is interesting. It may be there to stop the wheel "ringing", which is sometimes done on disc wheels, but I suspect it may have been done to enable a sling to be used to hoist the wheel set onto the lathe (etc.) when necessary. Anyway, I put holes in mine. Here they are, with one set mounted on a temporary axle.
IMG_20200503_180343 by malcolm brown, on Flickr
Underneath is the only drawing I have been able to find of 99 3462. I blew it up on a copier to A3 size from a small version in a book. It is not reliable as the dimensions include one of 600mm (gauge) and one of 1800mm (width over cab and tender) but the latter is definitely not three times the former when one puts a rule to the page. So useless for measuring off it - which is bad practice anyway - but it does give a general idea of shapes and proportions.
The wheel castings only had a very shallow recess on back and front faces. Real disc wheels are quite "thin" between the rim and the boss, so I have turned a much deeper recess either side. They are still over scale thickness but look much better.
For the driving wheels, I found some slabs cut from steel bar which, again, have been under the workbench for many years, I like steel for driving wheels, so these are being turned up to suit. By close of play this weekend, I had faced both sides and turned up the front face on three wheels, with five more to go followed by the treads and rear faces. As with the tender wheels, I am recessing both sides quite deeply. It is making a very large pile of steel swarf....
On the prototype, all the wheels are hidden from view. But the driving wheels have balance weights and appear to have holes through the web of the disc. When I visited, the loco was only moved over a pit at the very end of the day when the staff were keen to get home, so my time down there was limited and I didn't get any decent photos or dimensions. The shot below, from the internet, is the best view of the wheels I have. It also shows how the frames are plated over at footplate level so the wheels are invisible from on top, Nevertheless, I intend to add balance weights and some sort of holes in the web. Then at least I will know it is more or less right....
934742_651518544953180_2769740261498220148_n (1) by malcolm brown, on Flickr
Here is where the driving wheels are up to - three done on the front face, one in the lathe, and four blanks lined up behind.
IMG_20200503_165712 by malcolm brown, on Flickr
As I said, nothing very exciting at this stage of construction, but there are some interesting features yet to come. More another day....