Question about side & face mill tooth geometry.

[Pete O]

I've been dreaming up a jig to sharpen horizontal mill cutters on the surface grinder and have come up with a fairly simple design that should enable dressing of the sides of the face & side cutters. I was discussing it with a bloke at work the other day who is an ex-toolmaker and he thought that there was a taper in the teeth of these cutters, i.e. the tooth is narrower at the root such that when trench cutting, only the outer edge of the cutter will actually contact the sides of the cut.
I have checked some of my cutters with a mic and there seems to be a very slight taper, maybe .003 from the tip to the root but these cutters are all showing heavy wear )hence my desire to sharpen them) and I'm not confident that there is a taper designed into the cutter. If so, the sharpening jig will be somewhat more complicated but still do-able. I was under the impression that the sides of the teeth should be parallel. Can anyone confirm whether they should be tapered or parallel please.

  side-and-face-milling-cutters-250x250.jpg (Size: 18.24 KB / Downloads: 59)

[wawoodman]

Speaking only from woodworking experience, I would think they should be tapered.

[TomG]

I have a college text on cutter sharpening by Cincinnati, but you think I can find it when I need it? No.

In my experience, slotting cutters like that should have a slight taper, maybe 1/2º per side. Otherwise, the teeth would rub on the sides of the slot and generate a crappy finish. That's the same reason why end mills are not 90º across the end.

Tom

[Dr Stan]

+1 on a slight taper.

[Pete O]

Thanks for the replies. I also found a document that suggests a taper of approx .003 toward the hub, which is consistent with what the worn cutters seem to have.
Weather here is abysmal at present so I have an excuse to leave other tasks and faff around in the workshop for a bit, will see if I can make some progress on a simple sharpening jig.