I started with some 3/4" square steel bar for the crank, drilled and reamed for the reduced end of the crankshaft and the big end pin.
Using a couple of 1/4" stub drills in these holes it was easy to flycut the taper on either side.
Then with the vice mounted on the rotary table it was just a simple job of winding the handle to form the boss and reduce the arm to thickness.
The two ends were rounded over using filing buttons and the keyway cut with a broach.
Here it is completed along with the crankshaft and big end pin. I will fit a 1/16" sq key and Loctite the crank to the shaft on final assembly.
Some 1/4" x 1/2" flat stock was centre drilled and then the middle reduced down as the first step in forming the con rod.
Then over to the mill to add a pair of 1/4" reamed holes.
The big end uses a split bearing retained by a strap and adjusted with wedge and cotter. A strip of 1/16" sheet was cut off and machined to 1/4" wide then a simple jig made to bend it in, all you need to do is lay the strip on the jig and drive the round inner former down into the slot with a drift and big hammer.
As the wedge and cotter are only 1/16" thick my usual 1/8" parallels won’T do so a steel rule was packed up off the mill table and an 1/8" spot drill used at one end to give the required taper. Its then just a case of setting the work against the top of the rule and milling straight across.
An off-cut of bronze was milled down to the required size then reamed on the lathe followed by cutting the recess and finally parting off.
A quick bit of filing with some buttons to guide me and the bottom bearing was taken to its final D-shape. The little end bearing was turned and pressed into the top hole.
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