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CNC Machinist: If Machining a 2 Stroke Crank?

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Armilite

Well-Known Member
Joined
Sep 5, 2011
Messages
3,738
Location
AMES, IA USA
If you wanted to Machine a 2 Stroke Crank which is Pressed together in a Hyd Press, let's just use a Rotax 277UL Crank to make it Simple. You can Buy Rod kits with Crank Pins and Bearings fairly cheap. You can Buy the Crank Bearings. You can even still Buy some Replacement PTO Ends for, the 377/447, 503, 521/582, and 670. I haven't ever found anyone who makes the Mag Ends.

Most Crank Wheels Avg around 4.0 to 5.0" OD Max and the PTO/MAG Ends each Avg around Max 6.0" Long, so a piece of raw stock 5.0" x 6.0" with a little extra length for Clamping in a Lathe.

My question is, with a piece of raw Stock that has already been Faced off on both ends and Center Drilled, and OD turned for the Max Crank Wheel OD Spec, could a CNC lathe with a Tool Changer, finish the Crank in one setup?

1. Finish PTO OD Contour
2. Finish PTO Center Drill Hole to Size & Tap the End
3. On doing the Mag End Contour and Thread the End OD for Flywheel Nut.
4. The Bore & Ream Crank Pin Hole for whatever Stroke you're using?

A CNC Lathe something like this one, a 1994 Okuma-Howa ACT-20 with FANUC 18-T control Includes 8" chuck.
 

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