Now to turn my attention to machining the top of the cylinder block. But before I do I want to machine the tappet cavity in the side. this is indicated below.
Since I am still working with a large chunk of aluminum, I need to machine down a bit to get to the pocket.
Below you can see that there looks like there is a pocket inside a pocket. I do this because my 1/4″ end mill only has a 3/4″ length cutting flute and the tappet pocket is deeper than this. I don’t want to rub the edge of the end mill on the upper pocket. Also you can see that the upper pocket has only a roughing mill pass, while the deeper, actual tappet pocket also has a finishing milling operation.
I make a 3D model of cylinder block with only the water jacket area around the cylinders features present. Note the extra material at the top that needs to be machined off because I originally squared off an over sized block for the work piece. In the picture below this extra material is semi transparent and indicated by an arrow. Also you can see a ledge that has been incorporated to the model. This machining operation requires a reach deeper than my .75″ flute length end mill, so at .7″ I step out a tad to prevent the side of the end mill from rubbing as i mill further down. I know, you are thinking why don’t I just buy a longer fluted end mill. I could, but I am altering the design to accommodate what is in my tool drawer.
Then I likewise create a model for the holes on the top of the cylinder block.
My little CNC router does not have much Zed clearance, so I can’t drill, so I essentially use a small end mill to spot drill, then go to the Mill to drill, ream and tap the holes as applicable.
And below is the final result of the cylinder block top and bottom machining.