Stephenson’s Rocket

[Bob Wild]

Just starting my new build. This time of Stephenson’s Rocket. The best plans I have found are from Julius delete Waal. In order to fit it in my lathe I am building it at half the scale of his drawings, which is a bit of a pain. Interestingly he says it is designed to be made in wood! That sounds a bit of a challenge. The main problem though is that he has completely ignored all the valve gear, which to me seems a really interesting part of the engine. One of the reasons for starting this thread is the fact that whenever I am stuck I can rely on some members to give me good advice and suggestions. So this will not be a detailed build log, but I will report my progress at any interesting stages. Here is the assembly drawing and my start on the chassis (not very interesting)

Bob

 

[Fidlstyks]

This was one of my plastic model kits I built some 50 years ago. I have aspired to build one every since.
I found this on Amazon as a wood kit, for $42 E with 20 dollars shipping, with one being built in a video on YouTube.
I think I will order one and keep it for a someday build, as I have other model's planned ahead of it.
Of course I would build it as a live steam model.

 

[Fidlstyks]

I Googled this and found another thread on another site and in it a reply mentioned a book "The Engineering and History of Rocket" by Michael Bailey. I found this on Amazon and ordered a used one for under $35. The reviews stated there is enough information to build one. So will be finding out! I can let you know.
The wooden one from Amazon out of UK does not look refined enough to use as patterns to sand cast parts from.

 

[Zeb]

Looks like a great project for sure.

 

[Bob Wild]

Well on with the firebox. Started with a wooden former to shape the sheet brass round. Julius’s design is simplified so I decided to add the rivets as per the original. Marked out the positions just for guidance but thanks to my DRO this proved to be fairly straightforward:

 

[Steamchick]

I trust the boiler will be copper, not brass, for longlevity? (Brass can suffer de-zincification and fail after a relatively short life - spoils a good model).
K2.

 

[Charles Lamont]

I trust the boiler will be copper, not brass, for longlevity? (Brass can suffer de-zincification and fail after a relatively short life - spoils a good model).
K2.

From the OP, I concluded it is not a working model (?)

 

[Steamchick]

Bob,
Here's something from an earlier thread...

https://www.modelenginemaker.com/index.php?topic=9712.0
Any use for the Valve gear? - Brian Rupnow seems to have a working solution...
K2

 

[Bob Wild]

Thanks K2 and Charles. Yes, I have seen that earlier thread. I hope to make this driven by air. I have even earmarked a place in my garden where I could even have a circular track, but that’s a long way in the future. I would love to run on steam but the thought of all that silver soldering on the fire tubes and water jacket in the firebox is way beyond my abilities as still a relative novice. There is a wealth of info at the Science Museum and the Search Engine at the NRM so I’m trying to make this as accurate as possible.

Bob

 

[Steamchick]

Hi Bob, Do not be put off by the thoughts of "silver soldering"...
The manufacture of a boiler is as much down to correct design and making of the parts to fit correctly - with appropriate joints and clearances for the capillary action of silver solder to penetrate the joints. A skilled plate worker - as you must be to make a decent job of the plate work on the model - should have no problem making the components of the boiler. There will be people in a local club or somewhere who can assist in the actual soldering, or do it for you? Videos on Utube are very helpful, and make it look quite easy - with correct materials and a big enough blow-torch it is. Clean and pickle properly, and pre-flux the joints. Use a 55% silver rod, correct flux, work quite quickly (so as not to "burn" the flux) and apply enough heat, and you should have no problems. A brick hearth considerably helps retain heat while working, and the biggest issue I think is wearing suitable safety equipment. (Leather fire-proof gauntlets, apron, eye protection, ventillation, etc.).
Your boiler will be a very simple design, just 2 dished end plates, a tube for the shell, and small tubes for the fire-tubes. (Stephenson's ingenious design! - Oft overlooked!). Just make it with firetubes longer than the finished size, then cut off after the boiler is assembled and soldered.
Simple?
Hope that hasn't put you off?
K2

 

[Bob Wild]

Thanks K2. A bit late for the Rocket. I will bight the bullet next time. I’m thinking of perhaps a traction engine for my next project. I enjoy a challenge really.

Bob

 

[Bob Wild]

Got these castings from my local supplier. He does a good job at a very reasonable price. Machined the boiler end plate and fixed 150 rivets. So now I have finished the firebox assembly. Had a minor catastrophe when I was cleaning up some utensils for ‘er indoors with some Kilroc K in the sink next to my work bench. After an overnight soak everything was attacked. The brass was really heavily tarnished and anything steel had rusted instantly. Took me ages to polish it all away. Had a look on the label and it said that the main constituent was formic acid. It did give off a very pungent smell but I don’t know what the chemical reaction was. So I thought I had better paint it all to prevent any further mishaps. But I am quite pleased with the results, next up will be the boiler.

 

[Bob Wild]

Started on the boiler. There was a minor problem insofar as my homemade roller would only fit 4in sheet, so I had to make some more rollers that were wide enough for this model. But it all turned out good in the end. I also made two discs so that I could skim the end faces to the correct length. Quite pleased with the result:

 

[Bob Wild]

And another thing - I have been thinking about the boiler lagging, which was in wood on the original. However I was wondering if it would look more realistic if I used metal, since the grain on wood at this scale would be almost invisible. Any thoughts from the experts would be most appreciated.

 

[lee webster]

I think I would go for real wood. I think the grain would be visible. Having said that, I am using a sheet of glossy printer paper with woodgrain printed on it to glue on the body of my one tenth scale model car which has a wooden body. I found several suppliers of wood veneer, but I am making four models and want them to look the same. I won't know if it looks right until the cars are finished. As a carpenter I have to say that properly finished wood is hard to beat, looks wise!

 

[Steamchick]

If you soak wood to draw-out the grain, especially on a wood with dark lines on a light wood, then it will look OK.
Lee can surely explain the method better than I, and recommend a wood to use?
I use balsa, and varnish, and mark plank lines with a black ball pen. But the varnish hides the near invisible grain anyway....
Just for anyone's benefit who wants to make a live steam model, jonted seamed copper tube is no longer approved for boilers to be certified, so don't make one, only to be dissapointed when the boiler inspector refuses to certify it. For a static model, of course this is OK.
Enjoy!
K2

 

[terryd]

And another thing - I have been thinking about the boiler lagging, which was in wood on the original. However I was wondering if it would look more realistic if I used metal, since the grain on wood at this scale would be almost invisible. Any thoughts from the experts would be most appreciated.

Hi Bob,
Sory that this will be long winded, but here goes - I would use real wood. I use wooden stirrers glued with PVA white glue on to a fine muslin or cheesecloth which can then be wrapped around the boiler. You don't have to buy lots of expensive coffee to get them, they are as cheap as chips off the normal web auction sites etc. They are available up to 7" long but they can be cut to length and joined while glueing to the muslin if longer is needed. I have done it as follows:

Long+short,
Short+ long,
Long+short ,
and so on, alternating.
​

The long/short lengths should be devised so that the boiler bands cover them in situ. I hope that makes sense.
The grain in these stirrers is nice and fine, almost in scale. If you are really miserly like me I use strong tea to soak and colour them. This will raise the grain as any woodworker will tell you, but they can be lightly sanded down which will remove the coarse raised grain as well as some of the colour but you can then soak them again in the tea to darken the colour without raising the grain.

The wood lagging on Rocket was of course painted yellow so the 'tea trick' above isn't really relevant in this case but other veteran boilers look good with stained wood, with a satin laquer/fine varnish finish. Rattle can laquer from Halfords gives good results if not applied too thickly , but I use an airbrush for a fine finish.

TerryD

 

[Bob Wild]

Thanks chaps. So the consensus is to stick with wood. So be it. I like the idea of sticking the planks to a piece of muslin, but is there not a risk of gaps in the joins appearing when you bend it round the boiler? I’m looking forward to seeing it in bright yellow but unfortunately that will be one of the last jobs to do.

Bob

 

[lee webster]

In my ignorance I thought that the boiler cladding was varnished wood. It appeared to be in the drawings above. My mistake.
If the engine is going to be steam powered I would use wood. I have never had to raise the grain on a piece of timber, but it's an easy thing to try. If it isn't going to be steam powered, I would still prefer real wood, perhaps with raised grain so it can be seen through the paint, or, if you have access to a 3D printer, print them with a grain pattern in the plastic. I am not sure how to do the grain on a 3D print, perhaps engrave it on afterwards?

 

[Bob Wild]

Got the chimney finished. The corona was an interesting challenge. Being such a thin wall I made a wooden plug to fit inside it. Then milled down with progressively smaller bits staring with 8mm then 7, 6, 5 and finally 4. After I was able to file it smooth by hand. As I mentioned earlier, it does look impressively huge!
By the way, there is a metal piece in the first pic buried in wood chips.