Hi Martin

If you are used to using 2f slot drills and 4f milling cutters stick with what you know, as said some will plunge cut and sometimes 3f is better than 2. Nowadays there are also many makes and types of carbide tools available, some may be usefulf for steel but I believe you will obtain satisfactory results with HSS on brass and bronze.

Emgee

If you actually want a slot the same size as the cutter you need 2 flutes. The reason is that the cutter is deflected sideways by the cutting force, not by much. When the tooth is at the end of the slot, the deflection pushes the cutter into the side of the slot and makes it wider. With 2 teeth, only one is cutting at any time, so it doesn't make the slot wider.

Otherwise more flutes is better, and I'd have a try with ripper cutters, finish isn't as good, but by jove they shift metal

**LINK**

Upto 6mm I tend to use the FC-3 cutters which are 3 flute and quite reasonably priced when on offer from the likes of MSC, 3mm would be about £4.50 uncoated.

Once you get over 6mm Ketan's Premium HSS start to become the better buy. I do find the long series ali ones can chatter a bit though in the 6mm size.

Might not be totally relevant to milling cutters but as others have said, you do have to pay attention to the type of cutter you use for different materials. Harder does not always mean better, it quite often gives a poor finish on those softer materials

The ARC polished aluminium grade carbide tips, sold alongside the sumimoto tools, absolutely fantastic for plastics, use the steel grade one and the finish is understandably poorer.

Michael W

Edited By Michael-w on 01/05/2017 22:21:33