Re: Cutting a totem Pole

--- In CAD_CAM_EDM_DRO@y..., "vrsculptor" <vrsculptor@h...> wrote:

> Fred mentioned a project close to my heart, making a totem pole

(well

> actually sculpting in general). As an exercise, assuming you had a

5

> axis mill (x,y,z) plus a tilting rotary table (a,b):

This is where the home built capability stops. You can only get 4
axis controllers commercially in the low end cost range. It is
rumored that EMC will contour more, but I heard it on a pretty good
authority today that the source for this might be "missing". ( If
anyone knows where the 6 axis source version of EMC is located,
please post it. thanks)

You probably don't need 5 axes, even if you can make one. With a
couple of exceptions, nearly any geometry can be cut with 2 linear
and 1 single rotary . The few exceptions can be covered with an
indexing 5th axis, rather than a contouring one. ( typical would be
the inside of a donut, inside of a closed mouth glass or bottle,
etc.) These require the ability to accurately process an undercut
AND do simultaneous gouge avaidance on the tool, shank, holder and
remaining material. This software is not cheap. The simulation
software alone for this is about $6000 and up. You need simulation
to prevent a booboo at the machine. Total package price for a
commercial 5 axis setup is at least $15,000, and probably more like
$25,000, just for software.

> 1. What would you use as a CAD output format (STL, IGES, DXF...)?

The

> choice of actual CAD program is dependent on the specific model you
> are trying to build and your preferences.

Stl will present sufficient resolution for small models, but not for
large ones. IGES is the preferred method as the surfaces are defined
mathmatically instead of by triangular approximation, thus the file
is smaller, even with copius data definitions.

> 2. What CAM packages would you use? I've looked at Mastercam and am
> not real sure it could handle imported 5 axis nurb generated

surfaces

Nurb surfaces are not 5 axes. The machine may be, but the surface is
not. Names of some commercial packages that have some 5 axis support:
Surfcam, MasterCam, Cimetron, Unigraphics, Pro-E/Man, VisiCam, Delcam
PowerShape/Mill.

> 3. What would you use for a post processor? I haven't been able to
> find any 5 axis posts, even examples.

The post will be configured to the axes of your machine. It is more
common to have an articulated spindle joint or 2 than double rotary
tables for 5 axis contouring. The tool offsets are more predictable
if they are fixed in the spindle articulation hardware, rather than
varying with the way the tables are stacked at setup time.

> 4. If you got the post to work would any of the PC controllers
> actaully cut it if performance isn't a concern?

No. Shopbot is rumored to have 5 axis capability in their windows
version and have demonstrated a somewhat limited capability
articulated spindle machine. I have not seen this capability yet
from any of the other PC Controller suppliers.

The Vector rotary axis option includes simultaneous 3 axis contouring
using a rotary axis (which covers 97% of the carving application
requirement), and 5 axis positioning(which can cover the rest, with
an index move), and includes post processors for double tables and
double articulated spindles.


Best Regards,

Fred Smith
IMService

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