Re: All Round Machining

John Harnedy <machatak@...> wrote:
Subject: All Round Machining

Andrew,

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? Are balloon formers molds (or
positive forms) used to make balloons, or is this a blow-molding term?]

Another issue is that the cam software must take account of gouging in
ajoining surfaces. Be especially careful of approach and retract macros,
they can easly trip u up.

[What CAM software are you using? Does it let you get in and play with the
macros?]

Only subscribed to group a week ago and found it useful, especially the
maxnc articles. Must admit whilst maxnc 10, has a few limitations, it is
still a good entry point to many home machinists. Use it for plastics
and some balsa, so my real desire is faster feed like 500mm/min
(20"/min!! Anybody got it up to this speed? Would like to know details?

John

[I think the maximum speed with the supplied steppers (even the bigger 145
oz/in ones) is around 8"/minute. Crank it up much more than that and you
start getting weird behavior. But the good news is that MaxNC has come up
with a set of servo-motors and controls that are supposed to boost the
speed to around 45 in/min - not impressive by the standards of "big iron",
but quite a leap in performance from the steppers. Not having to worry
about lost steps would be a boon as well. I've ordered some for my MaxNC 15
mill, and will let you know my opinion when I've got them installed and
running.]

Andrew

Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com