For the full floating wrist pins, I started with some 12L14 unhardened precision ground shafting from McMaster-Carr. This shafting, p/n 1327k52, has a diametrical tolerance of +0.0000″ to -0.0002″ with a 10rms surface finish. The aluminum rivets used for the buttons were also purchased from McMaster (p/n 94439A330).
If you make this a press fit on the rivet, you risk expanding the pin so it will no longer fit your wrist pin holes in the piston.
The couple of thousandths of clearance you left when drilling the hole will provide for the proper film thickness to allow the retaining compound to work properly.
Here I’m using the mill vise to hold the rivet in place while the retaining compound cures. Don’t use the vise to force the rivet into the hole – press slowly by hand to allow the excess retaining compound to escape.
If you force the rivet in place from either too tight of a fit or without letting the excess compound escape, you’ll expand the wrist pin rendering it unusable (don’t ask me how I know).
Now add the 1.000″ spherical radius to the head of the rivet turning it a wrist pin button. The tool I’m using for this is my boring head ball turner.
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All material, including the CAD drawings, relating to the construction of the Hodgson Radial presented on this site is free to use any way you see fit. However, no guarantees are made regarding the accuracy or correctness of the material presented here.