Hi Mike, having recently built this engine I've just had a look in the workshop and found the cutter that I used. In the end I went for a pretty sturdy and solid parting blade rather than using an insert cutter. I shaped the edges to give the stress relieving corner radii and then created the central notch with a diamond hone.Guys
I am struggling!!!
I am trying to machine the Kiwi crank and so far I have failed to find the correct cutter. The picture shows the tools I have used all of which have an overhang of around 35mm. The tipped parting tools seem to "wobble" and I fear the carbide insert will spring out. The parting blade isn't really suited to the task and the tool in the rear tool post chatters badly at all speeds. I have cut a relief into the center of the cutting edge. I have tried the tipped parting off blade in the read tool post but it wasn't stable. I believe the tool height is correctly set.
I am sure it can't be that hard but so far I have failed to find a workable solution. I don't know the grade of the rolled mild steel but it came from a very reliable supplier some years ago and was used for general machining is a development model shop. I annealed it before use. It drills very easily.
Any insights would be appreciated.
View attachment 138966
By working the cutter from side to side with each cut only a small area of the blade is cutting at any point in time time. I first roughed out the material and then was able to get a very good fine finish cut with this method.