Part 9 by Vince Cutajar

The USS Monitor was an ‘ironclad’ steam ship which famously saw service in the Civil War in the early 1860s. The ship's engine was designed by John Ericsson as a "vibrating side-lever engine." He had created similar engines before and decided to use the design again because of its advantage for a small, low-riding warship.

Most steam engines of the time had vertical pistons, which occupied a lot of space and made them vulnerable to enemy fire because they were partially above the waterline. In contrast, the Monitor's 30-ton, 400 horsepower engine had pistons that moved horizontally, which reduced the height of the engine and allowed it to be mounted below the waterline.

Although a successful fighting ship the Monitor was not stable in rough seas due to its formidable rotating turret and sank in the early hours of January 1, 1863.

The engine was recovered from the Monitor's wreck site in 2001. It is now resting upside-down in an alkaline solution to inhibit corrosion. Over the coming years, conservators will continue to clean and separate the many different pieces of the engine to preserve them properly.

The first model Monitor was shown at Harrogate in 2014 by Brian Stephenson to the design of Bob Middleton. It was built without castings, like Bob’s other designs. Julius de Waal has produced these CAD drawings for both metric and imperial (see here) versions. Drawings can be downloaded for personal use only.

This one is built to Julius’ metric drawings.

To do the pistons and piston rods I had to go shopping for the material.  I need some 5mm stainless rod and cast iron for the pistons.  Never bought cast iron locally so was not sure if I would find any.  Went to my usual supplier and was pleased to hear that he had cast iron.  Only problem that for a 26mm diameter piston I had to buy 40mm diameter!  The other problem was that he could not give me a piece of 5mm 316 stainless but a full 3m rod.  I thought this was going to be expensive but still got them. And believe it or not it cost me 6 Euro including the cutting.

Finished stainless steel piston rods (item 43) and the cast iron pistons (item 42A).
I made the piston end of the piston rod different than the plans.  The plans called for the piston rod to be screwed into the piston and locked with a nut.  I wanted to create a shoulder in the piston rod to locate on the piston so I turned down that side of the rod to 3mm and the piston is held to the rod with a 3mm nut and a locknut.

Took some time polishing the pistons to fit nicely in their respective cylinders.  Now I can move the piston by blowing in the inlet port.

The Piston Rod End.

I was not happy with the first piston rod end that I made.  This was the second attempt. Started off with a length of 12mm square brass stock.  Centre drilled one end for the live centre.

Fitted to the lathe and for the first time thought I would use a collet instead of the 4 jaw chuck to hold the square stock.
Started turning the middle part of the material and then finished off with a left hand and a right hand tool.
Then drilled and reamed the two 6mm holes.
More work on the piston rod ends.  Rounded the ends on the rotary table and then they were separated (hacksawed) from each other.  They were put individually in the collet and trimmed to length and tapped for the piston rod.
Then the slots to create the fork were cut with a 5mm end mill and opened up to 6mm.
Finished and cleaned up.

Part one here  Part two Part three  Part four Part five Part six Part seven Part eight Part nine Part 10 Part 11 Part 12 Part 13 Part 14 Part 15 Part 16 Part 17 -

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