The material is Aluminum.
Could one lap the joint between collar and the throat before curtting the cooling slots?
With a ball endmill doing 3d machining you can't get a sharp inside corner and you can't machine any surfaces more than 90 degrees from the horizontal. But by mounting the part on a 4th axis indexer, surfaces at any angle can be machined. These parts look like they should be turned on a cnc lathe first and then milled.
Fred
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