johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment.

Category: Bolton 7 Stationary Steam Engine

BOILER PAINT

I am waiting for some new 2mm milling cutters to arrive before I tackle the steam passages in the triple, so I decided to apply some finishing touches to the Bolton 7 boiler.

The aluminium castings on the ends were removed, and painted with a high temperature engine paint.  While the boiler was in pieces I connected the steam exhaust pipe from the engine to the boiler chimney.

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The before shot. The engine and its boiler are sitting on a mantelpiece in our living room.

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It looks better with the ends painted matt black, yes? I suppose that I should have also painted the brass sides and copper boiler, but I really like those metal colours. 

Boiler for steam engine

Just a bit more finishing on this boiler.
At the chimney end there is now a removable cover to provide access to the smoke box (the round aluminium cover with the brass lever nut), and a sliding door to provide access to the firebox.
You can just see the Bolton 7 engine behind the boiler. They are both sitting on a marble shelf above the fireplace in our living room. I was amazed when SWMBO said that it could live there.
My 18 month old grandson loves to be lifted up to the “teamengine” so he can turn the flywheel.

Making a copper boiler

The boiler which powers the Bolton 7 steam engine is 250x100mm. The case is 1.6mm thick and the ends are 3mm thick. It has 7 x 6mm copper stays. The safety valve, pressure gauge, sight glass and valves were bought items. It operates at 60 psi but has been tested to 120 psi. Propane gas fuel.

Bolton 7 Gunmetal castings

Castings used to make the Bolton 7 engine. These are a hard wearing brass alloy called gunmetal. The next post is a picture of the cast iron castings.
Part of the expertise in making these engines is the technical challenge of accurately machining these lumps of metal.

Bolton 7 Iron castings

A lot of people who see my engines do not know what castings are, so here is a photo

Bolton 7 Boiler changes

The steam exhaust from the Bolton 7 now exhausts into the fire box, and ultimately up the chimney. I am not sure if this will work well. Concerns that the exhausted steam might interfere with the gas flame. Wait and see when I next fire it up! But that will not happen until I make and install a displacement oiler. Another week or two.

BOLTON 7 STATIONARY STEAM ENGINE CHANGES

In the earlier video showing this engine running with steam, there could be heard a knocking noise. Last weekend I did a tear down to identify and rectify the problem. I found 3 separate issues. First the con rod big end was a bit loose, and required some tightening. Then I found that the threaded join between the piston rod and cross head was a bit sloppy, so that was also tightened, then pinned so it will not move again. (see photo). Finally, and of most concern, the 3 bolts holding the cylinder to the bed were loose, allowing the whole cylinder to move slightly. I think that this movement was what was allowing the piston to hit the cylinder cap in use, causing the knocking. I replaced the BA screws with metric 5 cap screws. Much stronger. Much more permanent. And no more knocking.

Bolton 7 working with live steam

This is the first run of this engine using steam. I have previously had it going on compressed air, but there is nothing like real, live, hot steam!!

It did show up a few problems which I will have to fix. A few minor leaks, need for a displacement oiler, and need to adjust the length of the piston rod. You will hear a knocking sound in the video. I think that is due to the piston just touching the cylinder cap at the end of each stroke. Not difficult to fix, but will require a complete teardown of the cylinder=piston.

to see it click on the link below.

Boiler and engine incomplete

Gas fired 4″ boiler Bolton No 7, double action, single cylinder stationary steam engine. I will download  a video of the engine operating on steam, soon.  Keep watching.