The connecting rods come as castings and in real life would have been forged so we need to get rid of the evidence.
I picked up a tip on YouTube to put chalk on a file when draw filing as this helps to get rid of swarf from the teeth of the file. I am using a Barcho fine tooth flat file to start then working back further with 180, 240 and 500 grit emery cloth. I had a demo of the technique and the alternative use of a flap wheel from Matt at Polly and given the risk of wrecking the profile with a machine I am hand finishing them.
I have managed to complete one of the six rods and I quite like the look that I have achieved. The edges are still nice and crisp.