I had a first go at Fly cutting with the mill last night.
The pieces of bar in the last post are what’s known as hot rolled steel. Hit rolled steel is the cheapest way to buy steel but you do get an outer coating of oxidisation and the edges are far from flat/square
For the two larger pieces I needed to square up the edges and then flatten one face. I had two options use an end mill or fly cut them. I used an end mill on the edges bt for the larger area it would have taken a fair amount of time to flatten it with my largest end mill with is 10mm. With a fly cutter I could do the whole area in one or two passes at each cutting depth.
The other thing that appeals to me about fly cutting is that it uses a piece of tool steel similar to a lathe tool and is something that I can confidently re-sharpen in the workshop on the grinder. I have no means of re-sharpening end mills so they become quite expensive consumables.
This is the fly cutter in action, it was spinning at 740 rpm and I was taking off 0.04mm per pass