I can't quite believe it but it was November 2012 when I bought a set of castings for Heinz Kornmuller's Mercedes aero engine (that’s his original engine above) from The Engineer's Emporium .
I decided to start with the crank case. Now, all of the castings for this engine are a devil to hold.
I dogged the top half to my Taiwanese mill and skimmed the ends to give myself a datum. I also ran a mill along the feet for another straight edge.
Then a bit of messing with the height gauge to find the centres.
Next drill and bore for the con rods. Now, the drawings for this engine could be a bit clearer and show more of the detail. Fortunately, I was switched-on enough to think of the block hold-down studs and took the opportunity to centre for them and the push rod bushes by coordinate drilling. In other words, by counting the numbers on the dials. One day, I am going to invest in a DRO!
Then I turned it over and skimmed it to thickness using a pile of slips and a clock gauge to measure it.
Spot face and hold-down holes.
First component well on the way!
The sump is also an awkward casting to hold. I gave in in the end and simply gripped it gently in the vice whilst I skimmed the joint face.
Then turned it over and skimmed the other faces.
The two castings match and line up very well so it was simply a case of centre popping the bolt holes by eye and spotting through before tapping. They are held together temporarily with bolts.
Once I had a crank case, I thought I would have a go at the cylinder blocks. Again, these are most awkward castings to hold!
There are very few good datum faces on the things so I held them by the base flange in the vice and took a skim across the top.
Then turned them upside down and dogged them to the table. This worked out OK but there is very little meat on the base flange so so I had little room to manoeuvre.
I skimmed them to height across the base and then ran around the periphery to clean to size. Using the wonderful edge finder, With the corner as datum I drilled the stud holes. Then it was simply a case of boring to depth, or so I thought....
Part two here
