28/12/2015

I had a break from other stuff over the Xmas period and did a bit more CAD work. The drawings that Andrew sent me included the later single slidebar, the multi ledge crosshead slipper, and the later slidebar brackets.

The slidebars are in two halves with the crosshead slipper sandwiched in between. I'm not sure if I'll copy the multi ledge design or simplify it by making the slipper square with a simple slot in the slidebars.

The slidebar brackets were a bit fiddly to model and the right hand one includes a platform for a Wakefield lubricator to be mounted. The drawings show that this platform was extended on later versions so I presume this is the version Red Devil was fitted with as I believe 3450 was the last 25NC built.

The drawings for the original brackets show them fitted to the frames as well as the beam that goes across the top of the frames. These later brackets are only fastened to the cross beam. I didn't seem to have a drawing for this cross beam so for now I've 'guesstimated' the shape. There is a rough outline on one of the GA drawings to give a bit of an idea what it looks like.

The beam is bolted to a couple of brackets which are part of the original cast bed but on the model these will be separate items mounted on the top plate of the frames.

I also did a bit more work on the cylinders and modelled the end covers and the cover plates that fit over these.

There's still a lot of work to do on the cylinder blocks to make them look like the originals. I've had to make the blocks longer than scale to get a decent length piston to fit but it won't be that noticeable. The original cylinders had the rear covers cast in one piece but I'll be making them as separate pieces to simplify the machining. It won't show when the cover is in place to hide the fixing bolts.

The rear cylinder cover still has the bottom mounting lug for the old style slidebars even though it's not used anymore. Also, looking at photos of Red Devil, it didn't have the cylinder relief valves fitted to the front and rear covers, in fact I'm not sure any of the 25NCs had them fitted. Some photos of Red Devil show the front cover casings without the square cut out for the valve and some show it with. There were quite a few alterations made throughout the life of Red Devil so I suppose I'll have to decide which version to follow. At some point the feedwater heater was removed but I'll probably keep that. It also had a spell of being painted black and also blue but Red Devil's got to be red!

Work so far:

A long way to go yet!

12/01/2016

Another year gone!

I've been trying to draw a few bits when I can inbetween other things to keep this project progressing.

I've drawn all the support brackets on the top of the frames that hold the cross beams for the motion girders and the platform supports.

I wish I could find a way to produce decent quality jpegs from the drawings! Using a virtual printer gives very poor images.

At this point I decided it would be a good idea to split the chassis into two assemblies, one basic with all the crossbeam support brackets fitted, and one with all the crossbeams, motion girders, slidebar brackets and the platform brackets etc. fitted. This would be better than having it all as one huge assembly with a lot of constraints holding it all together.

Next I drew up the crossbeams that support the motion girders and the platform (running board) supports. I also realised that some of the drawings for the class 25 locos are used for the 25NC and I found the drawing for the support beam for the slidebar brackets. I also did the boiler mounting brackets. The supports on the rear cradle are welded to the foundation ring and can slide to allow for the expansion of the boiler when it heats up. The centre one fastened to the bottom of the barrel can also slide.

Next were the motion girders that support the expansion links and the weighshaft. These are quite complicated and took a bit of time to do.

I decided to have a go at the cowcatcher as it's such a distinctive feature but have only modelled the frame so far. The individual tubes with their flattened ends that bolt to the frame are going to be quite complex things to model so I've put those off for a bit! I also did the front steps.

Inbetween the two rear crossbeams are four channels that the plaforms or running boards bolt to.

Onto the cab platform supports next and this end is very complex with umpteen brackets and bits of angle! The drawings take some sorting out as they are pretty complicated.

Progress so far:

As a bit of relief I did the front two platform brackets just behind the front buffer beam.

There are lots of other brackets all the way along the chassis to support the platforms that run along the sides of the loco. I also modelled one that fits inbetween the frames just behind the two in the photo above but I may not need that. Red Devil has a much longer smokebox than the standard 25NC and the section of platform at the front and under the front of the smokebox is much shorter so this bracket may not be needed. The side platforms are also extended on Red Devil so the front brackets for those may be entirely different. Something to be looked at later.

So, the chassis so far:

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