Working on the top crankcase. Here is my plan:
- Square the stock up on all sides in the lathe.
- Drill the camshaft hole through the work piece, working from both the front and back, .05″ undersized. Use the bottom and right side as the datum.
- Mount in the mill and using the bottom and the right side as datum, drill and ream the camshaft bearing holder holes from each end.
- Drill a 1/2″ hole approximately in the center of the cylinder as a clearance for the flat end mill to enter.
- Mount in the vise with the bottom up and the right side against the vise face
- Machine the bottom using a 1/4″ flat end mill. Touch up the crankshaft bearing holder surfaces with a 1/4″ ball end mill. Used a .200″ step down ( .050″ fine step down) with a .050″ side cut. 1 hour, 16 minutes total machining time.
- Machine three flats on the center bearing holder surface, one for a center oil hole and the other two for the middle camshaft bearing mounting screws.
- Mount in the vise with the top up and the right side against the vise face and machine the top with a 1/4″ flat end mill. 28 minutes machining time.
- Center drill, drill and tap the 6 block mounting holes.
Squaring up the stock in the lathe. I left it over sized, but did not need to “re-square” up the work piece after the camshaft hole was drill and reamed.
Finished bottom machining. You can see small steps .0745″ down. the wall sides are .010″ thicker so the 1/4″ end mill can mill deeper than its .750″ flute length. this keeps the mill shaft from rubbing.
Machining the crankcase top surface
I also worked on the block, I brought it to exact dimension on the lathe before machining out the inside.
The engine so far.