The Steam Chest and Cover

The steam chest was a simple piece of lathe work although a milling machine could also be used if one is available. I chose to do all the machining in the 4 jaw chuck and even though I doubted the set-up myself the following seemed to work very well.

After cleaning the casting up with a file it was mounted in the 4 jaw with one of the large sides facing out. This face was skimmed and then the casting was reversed and the opposite side was slimmed. I removed as much metal as a dare whilst trying not to cut into the raised union sections of the casting. My cautiousness left the casting about 1mm over size which would have to be remembered for subsequent parts.

 

Machining one of the large faces

Next I machined the other faces in a similar fashion. None of the dimensions were considered critical but all sizes were kept close to the port face dimensions of the cylinder for things to look right. I also left 0.5mm on the two longer sides to make the cylinder lagging fit flush. This was a relatively quick set of cuts to make, as it was not necessary to centre the casting each time, just make sure it is square.

The last face to be machined was the face which had extra material to support the valve rod. This face was centred about a measured centre point and the faced flat. In the same setting the hole was centre drilled, drilled and reamed to size. I finished the counter bore with my small boring tool. The steam inlet hole was done on the drill press as it was not considered critical.

Machining the valve rod face.

The steam chest cover required more work with the 4 jaw chuck. I skimmed the front and back faces using packing where necessary to machine a plate of the right thickness.

Machining the back of the cover

Machining the front of the cover

I chose to finish the side of the cover using the vertical slide.

Trimming the edge of the steam chest cover.

Finally the holes were marked out in an even spacing on the back of the cover and then drilled through. The cover was then used as a template to drill the steam chest which was then used as a template to drill the cylinder casting.

 

The finished parts.

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