All posts by Tom

Hodgson Part 005, Bearing Retainer Plate

This entry is part 1 of 2 in the series Hodgson Front Crankcase Cover

After almost a 2-year hiatus, I was able to restart the Hodgson project. I have a small machine shop in the lab where I work at Harvard so I have a little opportunity to play on nights and weekends.

plate01I used a piece 2″ x 2″ square of 0.125″ of Aluminum 7075-T6 plate to make the front bearing retainer. A 3/8″ hole was drilled in the center of the piece to mount it to a scrap tooling plate in the mill vise, and the center of the part was zeroed.

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Quorn Part 104, Wheelhead Column

This entry is part 3 of 3 in the series Quorn Base

wheelhead_barI had a slight problem when making my wheelhead column. I couldn’t find any competent machine shop with a 4-axis CNC mill to run the spiral groove. So, I needed to come up with a way that I could do it myself with the manual machines I had at my disposal. My gearhead lathe couldn’t cut a 2TPI thread so I had to find a way to make this part on the mill.

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Quorn Parts 100/101, The Bases

This entry is part 1 of 3 in the series Quorn Base

basesWhen dealing with castings, you have to remember that shrinkage, pattern mismatch, mis-located cores, and uneven surfaces can all contribute to making these parts hard to deal with. I was forewarned and ready to deal with the cored holes not being in the exact center of where the final holes needed to be, but when measuring the left base casting for my CAD model, I discovered that it was about 0.1″ short.

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Quorn Split Cotters

06-cotter_plug_and_holeLike many others building Quorns, I decided to incorporate split cotters instead of splitting the castings as envisioned by Chaddock. One of the major problems with Chaddock’s design is the tendency for the painstakingly bored and lapped holes in the castings to close up when the casting is split and no longer allow the shafts to move freely.

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