What do you use for media for "Sand" blasting the aluminum to make it look like a casting.
I have been using "Black Diamond" slag, and it is a bit coarser and more aggressive then the finish on your parts.
I typically "Rough" machine the part from bar stock, then sandblast to make it look like a casting, then add the finish machined surfaces, holes, counterbores etc.
You are my hero.
I have yet to complete a single cylinder aero engine for fear of failure.Only piston and con-rod to finish up.Drawings came a UK Aeromodel magazine.
Quite a few were build and did run well with some powering planes and flew well.
When completed ,please post a video with sound effects.
My failure is because of bad case of fishingitis and boat disease.I fish every Sat. and Sunday.
Boat now being upgraded with marine electronics i.e. GPS/Chart Plotter,Fishfinder and Auto-Pilot.This weekend will
finish up a mini steam engine.