The rear seal plate is one of the last parts to be made from my 125mm diameter by 300mm piece of Aluminum 7075-T6. I bought a stick of this long enough to make the front cover, crankcase, rear seal plate, air guide, impeller, and a few fixtures. The diameter was needed to accommodate the crankcase so I did end up wasting a little material on the other parts.
While I had the parting tool set up, I used it to rough out the boss on the other side of the seal plate before parting it off the stock. This would minimize any heavy cutting while the part was clamped only by the shallow recess.
I moved the seal to the other side of the plate from the plans. The places the proper side of the lip on the “pressurized” side of the area. I also enlarged the center bore to 0.65″ to allow easy removal of the seal and allow oil to drain back into the crankcase.
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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.
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(CAD drawings are in AutoCAD 2010 Format)