Refurbishing an Old Model Steam Engine.

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Tony Bird

Senior Member
Feb 20, 2011
Reaction score
Cardiff, South Wales, UK

Thanks to a friend I am the proud possessor of the parts of an old fairly large model vertical steam engine.

The following photographs were taken of the engine being taken apart to assess its condition and what will have to be done to the existing parts before work is started on making the missing parts. As will be seen unfortunately isn't very well made.

As perhaps can be seen from the photographs the casting are very good but alas the machining of them not so. The valve fitting the steam chest is all that is left of the regulator that would have been operated by a governor, there is what might have been used as a drain cock in the top of the cylinders and the piston has a piston ring.

All the parts of the engine have been cleaned. First the parts were washed in paraffin, then washed in soapy water, and then boiled for 10 minutes or so in washing soda. Then brass parts were then scrubbed with wire wool and soap in warm water. The rusty steel parts were put in a caustic soda/water solution which loosens and removes the rust before resorting to the wire wool and soap. The larger screws and nuts having been cleaned were oil blackened, because of the rusting the very small screws will have to be replaced. The result of the cleaning.

Boiling in washing soda best done with your own pan when the domestic authorities are away.

Just out of the pan.

The cleaning helps in the removal of fixings.

After the wire wool and soap treatment.

The remainder of parts treated.

The small screws that will have to be replaced.

A plugged hole in the crank.

As can be seen from the photographs it isn't very well made. However given that it was possibly made by an amateur using probably a treadle lathe, a hand powered drill a hand shaping machine all using carbon tools. The most used tool probably being the file and all being done in indifferent lighting maybe it isn't so bad?

Because it is so out of square it has been mounted on a flat board to show where problems are.

Getting the axle over a centre line.

Centring the engine over the axle.

A bit of an issue with the cross head and the piston rod.

A little out of vertical.

Leaning a bit?

Not quite square?

A little bit out?

So far it has taken about a day and a half to get this far; I suspect it will take some time before I decide how to progress with the restoration. The new parts needed, will have to be researched. Correcting the lining up of components without too much re- engineering will be interesting. If anyone has photographs/drawings of a similar old engine which would be helpful. Though the engine came to me from Germany the screws are BSW and BSF the bore is 1.3/8" and the stroke 1.5" so it is likely made in the UK. If anyone has an unwanted 9" flywheel???

Regards Tony.

Yesterday SWBO went to London for a grandchild fix, so I had a longer than usual in the workshop. Having a little time left after doing what I wanted to do, I did a bit of work on the engine on the engine.

As it was straight forward as to what had to be done to the crankshaft so it was decided to work on this. The crank pin and the bearing slots were corroded. The crank pin was out of line with the shaft and the bearings eccentric to the shaft. There were two reasons the crank pin was out of line the shoulder that mated with the crank web wasn't flat and the crank web itself wasn't at right angles to the shaft. So the first job addressed was to square the shoulder removing as little metal as possible, with this done the corrosion on the crank pin was turned off again removing as little metal as possible. Later if the crank pin is deemed too thin it can always be sheathed.

To work on the crank shaft its ends had to have centres drilled in them. With this done the corrosion on the bearing was turned away reducing their size from ½” to 10 mm, as well as being corroded the bearings were quite eccentric to their shaft. With the same set up as for turning the bearings the face of the crank web was squared to the shaft, oddly the back of the crank web was square to the shaft.

With centres now on the shaft it will be possible to true the shaft itself to fit an eccentric and flywheel when they are made or found. With the bearings on the shaft reduced in size the main bearing that I have will have to be sheaved. This will be the next job along with making a copy of it. This will be done at the back end of other jobs as I am still thinking of possible ways to resolve poor lining up of the cylinder and its stand. A thick piece of sheet metal needs to be found to make a bed plate to mount the bearings and engine stand on.

Regards Tony.
Tony, I will be avidly watching this one! Glad you decided to post. You sure get a lot done in a day.

I have made a start roughing out a bearing. A couple of drawings have been made.

And I found a piece of 1/2" thick brass which used to be part of a clock case to make the bearing. One of the holes in the brass had to be plugged.

Regards Tony,

Before further work can be done on the new engine bearing the original bearing needs to be made usable. The bearing hole in the original bearing is now too large for the cleaned up slot in the crank shaft and the hole isn't round.

The hole was made round.

Plugs were soft soldered into each half bearing.

Half of the plug was machined from the bearings.

The bearing hole drilled.

Some further work was done on the new bearing.

Both bearings to date.

Regards Tony.

Well today has been a little more energetic than I had anticipated. My thoughts on what to do next on the engine was to find some material to make the engine's base plate from, to this end I went to my model engineering club in search of a 7"x 6" sheet of metal about a 1/4" or maybe 5/16" thick. The club holds a large quantity of steel for maintenance and members use. But try as I did I couldn't find anything suitable! Then a member who I had mentioned my problem to said well you could cut the end off this pointing to a 5 foot length of black mild steel 7" wide, just one minor problem it was 15 mm thick! Well as nothing else was likely to come to light so I thought why not? It certainly will be stable! So one of the club's band saws was used to cut 6" off the steel sheet; the piece cut off had a bit of box section steel tack welded to it which was removed with a Birmingham screw driver.

I am fortunate to live only about one and a half miles from the model club and I had been dropped off by SWMBO the intention being to walk home. Walk I did but towards the end of the walk the lump of metal was getting a bit heavy and it started to rain!

In the workshop the remains of the tack welds was removed first with a cold chisel and lump hammer and finished by filling.

My original intention using thinner material was to sink the engine's base plate into a wooden frame high enough to give flywheel clearance. The lump of steel I had only had square sides where it had been cut the other two sides had a shallow radius. There is often a certain amount of evolution in what I make often caused by the materials available. So the wooden base idea was scrapped the base plate would now be supported by columns yet to be sourced. To this end the flat sides of the steel base plate were radius using a file.

With the energetic bits over with some work was done on the new bearing. More filling; the edges of the bearing had a radius put on them and the column part split to make a bearing cap. Then two of the bearing parts were hard soldered together.

After cleaning up and a bit of cutting and filling the new bearing now looks like this.

At end of play today the parts so far made and worked on.

Regards Tony.

Tony, what is a Birmingham screwdriver?

Apologies I forgot the international aspect of HMEM. Birmingham screw driver is British engineering slang for a hammer; the theory being that the slot in a screw is just for removing it.

Regards Tony.
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Well, that certainly puts paid to what the guys here thought a BSD was!
Some one here got it wrong some time ago and for the 12 years I've been
hanging around the yard they've called a cutting torch a BSD. I'll just have
to straighten them out!

Ummm, what's your slang for a cutting torch??? :rolleyes:

Hi Pete,

Your question answered! I haven't heard that expression though; I do gas and electric weld after a fashion, I am largely self taught so not really have had any contact with people that can weld.

I had other jobs to do today so didn't get a lot done on the engine. The screws for the new bearing have been made. The bearing has been bored for the plugs to be soldered in and the plugs made and the top of the bearing has been profiled.

Regards Tony.

Before soldering the plugs into the new bearing like was done with the original bearing the top of the new bearing needed to be shaped. To this end some filling buttons were machined and hardened.

A piercing saw was used to cut around the buttons the result being tidied up with a file.

With bearings plugged and drilled the bearings were run in at low speed for a few minutes.

Some oil cups have been made and fitted which is about as much that can be done to the bearings and shaft for the moment. They could be fitted to the new base plate but given the state of the columns I doubt the shaft will end up in the centre of the plate. So these parts of the engine will be left like this for a bit.

I still haven't decided how to address the problems with the columns so the cylinder adjustments will be next. The steam chest is not parallel to the cylinder bore and is soldered to the cylinder. So it was removed and machined so the mating sides are parallel.

Regards Tony.
Getting more and more interesting - I am learning as I read. :)
Have put some of your ideas to good use already. Wish I were as handy as you in setting up the four jaw chuck, I would use it much more, especially with my larger lathe and chuck. DW
Hi David,

Wish I were as handy as you in setting up the four jaw chuck, I would use it much more, especially with my larger lathe and chuck.

I have a number of different size 4 jaw chucks and use them a lot. They are great when you needed to be accurate but most of the time they are used for holding odd shaped objects.

To continue:

With two of the sides of the steam chest parallel the next problem to be addressed was to make the valve face of the cylinder parallel to its bore. There was a 0.50 mm difference in wall thickness between one end of the cylinder and the other. A piece of brass shim was glued to the narrower end and filed until both ends of the cylinder were the same thickness.

The difference in height was checked on a surface table (sheet of glass). There was about 1.5 mm difference between one end and the other.

Machining away the high end of the valve face would probably break into two holes in the side of it; these holes probably had had something to do with the missing governor gear. So it was decided to plug these holes by soldering rods into them. First the threads in the holes were removed by drilling and over length plugs that were a bit loose in the holes were made. As it was important that their was a good penetration of solder and as they were blind holes small pieces of solder and flux were placed in the holes and the plugs placed on top of them. When the cylinder was heated and the soldered had melted the extended plugs were tapped down with a hammer not a BSD which would be too heavy!

After cleaning up the cylinder it was mounted in a 4 jaw chuck for machining.


With the valve face now parallel with the bore the ends of the cylinder were squared with the bore.

With both ends of the bore now square the bare of the cylinder was lapped.

The bore isn't brilliant so later after checking that the engine will work I might fit a sleeve.

As there is no register on either cylinder cover it was decided to make one. Before doing this to the top cylinder cover a threaded bush was soldered into the hole for the drain cock. First the body of the drain cock was annealed and straighten on one end threaded.

The top cylinder cover with soldered bush was then machined. It won't be as easy to machine the other cover!

The bits being played with yesterday assembled.

Regards Tony.

New studs and nuts have been made for the valve rod which has been straighten.

Slight bend.

Checking after the machining that the valve is still loose in its srap.

After a lot of thought the system used to turn a shoulder on the lower cylinder cover,

The metal of the engine stand has been found to be malleable so has been bent parallel with the piston rod.

A new screw to hold the cross head to the piston rod has been made and fitted.

Regards Tony.

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