Re: Re: All Round Machining

John Harnedy wrote:

> Like Patrick, I also divide the surface into segments usually 180deg,
> and rotate my tool cords to suit, then generate the toolpath. Only
> issues encountered is need to ensure u rough down enough to allow the
> ball nose finishing tool to have room to work. This is especially
> relevant with a 180 deg split. Have done many elliptical in cross
> section balloon formers using this approach.
>
> [Yes, I can see this could be a problem. I've been researching the
> availability of extra-long (6"?) but thin (1/8") ball-nosed milling
> cutters, and whether they would have a tendency to whip or snap. Anybody
> used these? Any luck? Carbide is more rigid than HSS, but also more
> brittle- or should I look for titanium?

I would immediately forget this, unless the work material is soft wood,
foam or the like. I have a couple long end mills. In particular, a 1/4"
diameter, 4-flute end mill with about a 1.5" length of cut is totally unusable
on any metal. If you go for even .001" feed per tooth, and maybe a .050"
length of cut, it starts screetching and giving horrible surface finish. This
is a stellite tool, I believe. Solid carbide would be a little better, but there's
no way a 6" long 1/8" diameter tool would work. With light feed, I don't
think it would break, but it would still vibrate horribly.

Jon