The Excelsior Project, 31: Head Tube & Engine Cases

These are all the pieces necessary to make the head tube casting. I made the initial pattern from steel and bondo (inside the top, middle box), and Pacific Pattern did the rest.  They contacted the foundry to find out how to mount it, and what sort of gates and riser(s) are required. Each foundry has their own way of doing things.  All this for ten castings for ten bikes. The two red and yellow halves are the core box. The "core"  is made in there, often from a chemically based sand that hardens when exposed to CO2. The core is broken out after the casting is poured, and I get a hollow head tube casting. The foundry only gets the red and red/yellow boards. After the castings are made, everything shown here will sit under a bench (collecting dust) for many years to come.

Fresh from Globe Foundry, cast in 356 Aluminum, and heat treated to T6 (sure hope I got all those dimensions right...). The two main cases were poured from the middle (more or less) and the circular protrusion (eg; middle of the bevel case) is the "gate" where the molten aluminum has been poured in. After cooling, the excess metal is cut off and re-melted for the next pour.

Close-up. Right now these two cases weigh 21 lbs, which is a lot. I wanted to go strong and machine them lighter, rather than discovering flex in cases that were too light-weight.


Flashback Fabrications Inc.tel 604-888-8785email
PO Box 401Lynden WA98264

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