Re: Dome question

I too use Mastercam and Surfcam. Its a matter of what kind of time do
I have? What kind of polishing does tooling want to do on this
surface? and How big of a program am I going to have.

On complicated models with multiple surfaces (100+), if I chose to
perform a standard cusp height, then it would either take forever for
the computer to generate the toopaths, or it would kill my computer.
So I opt for a standard step down. Most of the time I step down
only .001 other times I go to .0001
Other times, I know that a mold is going straight to the injection
machine, so then I have a surface finish issue. I'll program multiple
toolpaths in different directions and using different methods cutting
over the same surface in order to produce the best finish I can. the
machine times are 12+ hours but the tooling guys load it up at 5pm
and let it run through the night.

It all falls in that catagory of "More than one way to skin a cat"

--- In CAD_CAM_EDM_DRO@y..., Randy Gordon-Gilmore <zephyrus@r...>
wrote:

> At 07:12 PM 12/7/2001 -0000, yethdear0 wrote:
>
> >First- The program is a test program to be used to determine if

your

> >machine control would interpret full 3 axis motion.
>
> OK. I was just wondering more from a "if I really needed to

machine that"

> standpoint.
>
> >a radial cut. As you get farther out on the edge of the dome, the
> >cusp hight increases again. To prevent this, I would have

programed

>
> Yes, that "pie-wedge" aspect of the radial machining is why I

asked. I

> thought that in, say, Mastercam (which is what our shop at work

uses) you

> can specify a maximum scallop height instead of a constant step

over/down.

> As shallow as the dome is, I would think that stepping in radially

by an

> increment and then doing a circle at whatever necessary depth would

make a

> lot less machining passes, and minimum scallops.
>
> I have done a lot of "manual CNC" profile machining (like a

simulated

> extrusion), where I drew the cross-section of the shape and then a

parallel

> contour at .0005 outside it, then drew tangent circles representing

the

> ballnose that are tangent to the profile and cross each other at

the outer

> limit contour. Picked up on the centerpoints of the circles and

used them

> as the Y and Z coordinates. I was always surprised how few passes

it took

> when they were "intelligently" selected rather than "step down Z

amount and

> see how far over you need to move)...
>
> Best regards,
>
> Randy
>
> Randy Gordon-Gilmore ,----.___________ ______________

_________________

> ProtoTrains // = = === == || == == == = || == == ==

= == =|

> Rio Vista, CA, USA /-O==O------------o==o------------o==o----------

-o==o-'

> zephyrus@r... http://www.rickadee.net/~zephyrus