How can I make this feature?

[Asm109]

Start with oversized stock, drill a hole with a 7/8 Silver and Deming drill. Cut part to size.

 

[3Dogs]

Rotary table and end mill?

 

[DavidR8]

Rotary table and end mill?

Alas no rotary table

 

[3Dogs]

Alas no rotary table

So I suppose suggesting using a CNC mill is even more ridiculous?

 

[DavidR8]

So I suppose suggesting using a CNC mill is even more ridiculous?

Not really as I do have a CNC router but the spindle speed is way too fast for steel

 

[buffdan]

Hole saw, slow speed and down feed. Clamp part down to piece of scrap, wood, aluminum, etc.

 

[AGCB97]

I've done those partial arc cuts with annular cutters without any problem, but I have a good size Bridgeport.
Aaron

 

[DavidR8]

I've done those partial arc cuts with annular cutters without any problem, but I have a good size Bridgeport.
Aaron

I have a small PM-30 class machine.

 

[mcostello]

Do You have a boring bar for Your lathe? If the tool bit can be slid out a bit, there is your adjustment needed.

 

[DavidR8]

Do You have a boring bar for Your lathe? If the tool bit can be slid out a bit, there is your adjustment needed.

I do but I'm having a hard time picturing this setup.