Part 5 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. A double sized version can be found here. Drawings can be downloaded for personal use only.

This one is built to Julius’ metric drawings.

Time, now, for the cranks. First the Crank rod Bearing End (item 46) and the Crank rod Yoke (item 48) in aluminium.  Prepared four pieces from 12mm thick and 25mm wide flat bar.

Drilled two 3mm holes in the pieces that will be the bearing ends.

Removed some waste material although I suspect I could have avoided doing it.
Set up the 4-jaw chuck and machined the shaft.  Next drilled and tapped the shaft 6mm.
The four shafts finished.
The two short ones will be the bearing end.  Hacksawed and milled the material.  Then bolted it up together and put in the milling vice for drilling.  I want a 13mm hole but do not have that reamer.  So I step drilled until 12.5mm and then finished it with a 13mm end mill.
Cleaned them up a little and marked them with number punches before unbolting them. 
The yokes.  First cross drilled and reamed a 6mm hole.
Next did the cutout for the yoke.  The plans call for it to be 12mm wide.  I have an end mill that size but decided to start with an 11mm slot drill and then opening it up to about 12mm.  Then used the 12mm end mill to clean it up.
Rounded off the ends with the rotary table.
For the last operation on the yokes, I needed to set it up in the vice at 45 degrees.  So I used a plastic triangle that the kids use at school.
Yokes finished.
Next made the shaft that connects the bearing end to the yoke.  Used 6mm 316 stainless.  Threading the ends with a die.
Crank rods finished.

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