Hello Jos,
I tried years ago because a friend of my was very interested to build this engine but with no succes, for me this engine is out of my league...... Modelbouwforum is a NoGo for me.
A little late......
Back in 2011 saw at a show in the Netherlands a beautiful home build 6-cil Mercedes D.III done in 1/5th scale. I spoke to the builder who made it and the engine was in running condition. Forgot to ask his details and can't find or contact him anymore......
Enjoy,
1/5th...
EDM is a solution, thanks for the heads up.
A few years ago I have seen hexagon ER collets but forgot where..... (If I remember correct :rolleyes: ) So I have still hope to find some.