Milling a 5/16 keyway in EN 34 condition W

Seriously? That's only about Rockwell C 34 which is three fifths of FA. I suggest you try a milling cutter!

In article , Dave Baker writes

I agree. I presume this is the normal commercial available form, EN24T. If so, I have always found this quite reasonable to machine, not quite as free-cutting as EN1A but not that much worse either. Use a sharp tool and you should not have too much difficulty.

David

Thanks David, I thought a milling cutter would be a good idea myself, especially a sharp one. EN 24T is in condition T ie 55/65 tons tensile, En 24 condition W is the same material heat treated to 70/80 tons tensile. I was therefore wondering if HSS would work or would you need to go to something harder? I was also seeking guidance on speeds and feeds.

Andy,

I would use an indexable tungsten carbide tool, as indeed I would for the T variety. I know some people find they get a better finish using HSS, but I seem to get a good finish with carbide, even for fine cuts.

David

HV325 is about HRC 34. So HSS should cope quite easily. Go for M42 HSS (8% Cobalt) to get a longer life.

Feeds and speeds? Dunno, but I'd go with 80fpm and 1 thou per tooth because I'm a wimp :-)

Mark Rand RTFM

I'd try a 1/8" HSS end mill first to see if it holds up. If not you aren't out much and haven't ruined the part.

jsw