Isambarduk
Western Thunderer
I have been reworking a 'Tower Brass' GWR 1361 class 0-6-0ST that I bought as a non-runner from Randolph Chang when he closed down his factory.
Actually, like so many of the models from this stable, particularly the earlier ones, the upper works are well engineered and are quite well detailed compared to the lower works, which rather let the models down, but they do all run very well. On this model, I have undertaken my usual reworkings of the motion, draw gear, vacuum and steam heat pipes and so on but the frames required quite drastic surgery to set them at more nearly the correct distance apart and to spring the driven centre axle, which was rigid in the frames. All this is a bit 'run of the mill' but I thought there might be some interested in how I made a new smokebox door.
Unfortunately, the smokebox door on the 1361 class model is quite wrong but, being part of the ‘face’ of the locomotive, it needs to be better so I decided to make a new one.
I dare say that I could have found a casting, and I did make a few tentative enquiries at the G0G show at Kettering (and 'thank you' to Warren Shephard for a most helpful discussion), but I decided to make a pressing. I have done this before, but not for a door with a dished reverse curve such as this one, so it seemed like an interesting challenge. The principle is to make a punch and die with a means of restraining within it a disc of brass which is to be formed into the required shape.
I machined a hole in a piece of hardwood to form the die and I turned an aluminium ring as the restrainer, which is held to the wooden die with six roundhead screws.
I turned the head of the punch from a piece of dowel and mounted it on a steel shaft. The roughly sawn out brass disc (the blank) is firmly trapped between the restrainer and the die and the punch is pressed through the restrainer to form the blank into a dished door. Properly, the punch and die should be mounted in a press but I used my larger pillar drill.
For my first attempt (above), I used a blank of 15 thou (0.38mm) thickness and it was a reasonable success, but for the coggles in two places around the edge. My second attempt with a blank of 10 thou (0.25mm) thickness was as near perfect as things get in this less-than-perfect world, so I was well pleased.
The second task was to make the thin surrounding ring. The challenge in many machining operations is getting a good hold of the job; in this case, the simplest way that I know of is to use a ‘solder chuck’: simply put, you solder the job to something that you can get a good hold of, machine the job and then unsolder it again. I soldered a ring, which I had roughly sawn out of 15 thou thick brass, to a piece of waste etch of the same thickness and screwed this to a piece of hardwood (the back of the piece that I had used earlier as the die) that I could easily hold in a four-jaw chuck. In the image (above), the inside diameter of the ring has been bored and the outside diameter is now being turned to size.
There is a sizable hole in the front of the smokebox into which the dished part of the finished door (above) nicely fits so that the ring sits down flush on the front, centred on the surrounding rivets.
To complete the job, I reattached the hinges and made up a new set of dart handles. I modified the hinges slightly to look more like the prototype but, in the end, I decided against trying to move the lower hinge pin, which should be below the lower hinge, as there was really insufficient room for it in the correct place. This is one of the limitations of working with RTR models and kits, even very good ones; there are some design errors that require so much work to correct that it’s just not worth the effort, otherwise I would be better placed working from scratch.
So, to recap, here is the replacement door in comparison to the original:
And here is what the finished front end now looks like in comparison to how it looked before:
Now, you may agree with one of my friends who commented that I was nuts when I told him what I'd been up to, but it all depends what you find fun. I have enjoyed this part of the journey and I am a little closer to my final destination on this one, although there is a long way to go.
If there is interest in this kind of fun, I will be more than happy to write illustrated posts about other modifications (on this loco or on others that I have reworked, eg 8F, Black Five, Hall ...) just let me know.
David
Actually, like so many of the models from this stable, particularly the earlier ones, the upper works are well engineered and are quite well detailed compared to the lower works, which rather let the models down, but they do all run very well. On this model, I have undertaken my usual reworkings of the motion, draw gear, vacuum and steam heat pipes and so on but the frames required quite drastic surgery to set them at more nearly the correct distance apart and to spring the driven centre axle, which was rigid in the frames. All this is a bit 'run of the mill' but I thought there might be some interested in how I made a new smokebox door.
Unfortunately, the smokebox door on the 1361 class model is quite wrong but, being part of the ‘face’ of the locomotive, it needs to be better so I decided to make a new one.
I dare say that I could have found a casting, and I did make a few tentative enquiries at the G0G show at Kettering (and 'thank you' to Warren Shephard for a most helpful discussion), but I decided to make a pressing. I have done this before, but not for a door with a dished reverse curve such as this one, so it seemed like an interesting challenge. The principle is to make a punch and die with a means of restraining within it a disc of brass which is to be formed into the required shape.
I machined a hole in a piece of hardwood to form the die and I turned an aluminium ring as the restrainer, which is held to the wooden die with six roundhead screws.
I turned the head of the punch from a piece of dowel and mounted it on a steel shaft. The roughly sawn out brass disc (the blank) is firmly trapped between the restrainer and the die and the punch is pressed through the restrainer to form the blank into a dished door. Properly, the punch and die should be mounted in a press but I used my larger pillar drill.
For my first attempt (above), I used a blank of 15 thou (0.38mm) thickness and it was a reasonable success, but for the coggles in two places around the edge. My second attempt with a blank of 10 thou (0.25mm) thickness was as near perfect as things get in this less-than-perfect world, so I was well pleased.
The second task was to make the thin surrounding ring. The challenge in many machining operations is getting a good hold of the job; in this case, the simplest way that I know of is to use a ‘solder chuck’: simply put, you solder the job to something that you can get a good hold of, machine the job and then unsolder it again. I soldered a ring, which I had roughly sawn out of 15 thou thick brass, to a piece of waste etch of the same thickness and screwed this to a piece of hardwood (the back of the piece that I had used earlier as the die) that I could easily hold in a four-jaw chuck. In the image (above), the inside diameter of the ring has been bored and the outside diameter is now being turned to size.
There is a sizable hole in the front of the smokebox into which the dished part of the finished door (above) nicely fits so that the ring sits down flush on the front, centred on the surrounding rivets.
To complete the job, I reattached the hinges and made up a new set of dart handles. I modified the hinges slightly to look more like the prototype but, in the end, I decided against trying to move the lower hinge pin, which should be below the lower hinge, as there was really insufficient room for it in the correct place. This is one of the limitations of working with RTR models and kits, even very good ones; there are some design errors that require so much work to correct that it’s just not worth the effort, otherwise I would be better placed working from scratch.
So, to recap, here is the replacement door in comparison to the original:
And here is what the finished front end now looks like in comparison to how it looked before:
Now, you may agree with one of my friends who commented that I was nuts when I told him what I'd been up to, but it all depends what you find fun. I have enjoyed this part of the journey and I am a little closer to my final destination on this one, although there is a long way to go.
If there is interest in this kind of fun, I will be more than happy to write illustrated posts about other modifications (on this loco or on others that I have reworked, eg 8F, Black Five, Hall ...) just let me know.
David