These are two piston rods for an antique motorcycle engine. What makes these unique is that the engine did not have offset heads, requiring one piston rod to nest within the other.
The customer requested that I reverse engineer the originals in order to improve the performance of his engine by altering the design. Such alterations include: changing the center-to-center length, adding sacrificial bushings, and removing mass without sacrificing strength.
One of the most memorable challenges of this design was documenting the oil weep channels in the crank bearing rings. Because the originals were made in the early 1900's, they still relied heavily on hand machining and finishing. Consequently, the weep channels were added by simply hand grinding the channel into the bearing surfaces.
The customer was provided with the original 3D models, drawings for each iteration he wanted, as 3D printed pieces for test fitting.
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