You're planning a part--a hardened cam on a steel camshaft. Should you machine the unit out of a solid bar of tool steel? That's a lot of lathe chips. Perhaps forge the piece, and then finish-machine it?
Still a lot work. After hardening, the cam has to be drawn and the shaft ends annealed. How about making the cam and shaft separately and then join them mechanically as an assembly?
You're on the right track. By substituting cold rolled for tool steel in the shaft, you're saving on material cost. But machining is still somewhat involved, and locking device, such as a set screw, is subject to loosening under vibration. Now try the "assembly" approach again, but this time use a brazed joint instead of a mechanical one.
Simplest of all. No keyway, no key, no set screw. Minimum material, minimum labor and a strong, permanent, vibration-proof bond,
Extensions or projections on metal parts require excessive material (expensive!), and then a lot of work to machine away the unwanted metal (twice as expensive!). Consider what happens when you make an elbow shaped part from solid stock...
You're paying for metal you don't want, and the labor of getting rid of it. There's an easier way. Make the "part" as a brazed assembly, joining together standard tubing and bar stock components:
The assembly will be just as strong as the machined part. And you'll save materials, labor and weight. (The more awkward and complex the extension, the more you'll save.)
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