Re: [CAD_CAM_EDM_DRO] more on CADCAM raw material

FIK wrote:

> Johnno,
> Sorry but I'm missing something here.
> You state:- " That first thing for any CADCAM is to define the
> unworked part and how it is oriented on the work lane, be it lathe or
> mill.
> Why can't you just draw your unworked part ? In Dolphin and Vector
> you just need to draw a rectangle and that's your unworked part.
>
> That is exactly my point. I don't work in pre-defined shapes. I opened
> Feature cam and was very excited because it said "first define the part to
> be worked" Well I was using a flat ROUND disc or semi- obelisque/elippse
> shape, .375 tall. The ONLY choice I had for Miling was a rectangle. I could
> not define a flat circle, if I chose circle it defaulted to lathe and I was
> unable to over ride that, Then I tried sketch. I have a reason for wanting
> to draw a fiarly accurate shape which resembles a kidney bean as my raw
> part. By defining the unwrked material as it really is in my hand I can plan
> the approach to where I want to start the milling, and that would be
> reflected on the G-92.

Well, I've never used a cad package that REQUIRED you to define the
raw material shape. In ANY cad package, I'm sure you CAN define the
raw shape, however. In the case of an oddly shaped part, it would be a
very good idea to do so. I have carved shapes out of raw stock where
I only drew the desired 9finished) part outline, and I cut it to rough shape
on a bandsaw. The CNC mill then cut around the edge, cleaning up my
rough cutting, and bringing the part to the desired exterior shape.

> None of what I said was intended to offend anyone. It is hopefully
> constructive input or feedback to software authors that there exists a less
> sophisticated though literate market that can be met. I have been insulted,
> spoken to condescendingly and ranted at by help and support people from a
> variety of software providers. I stand firm in my opinion that any software
> that requires 398 pages of instruction manual or help files is too complex
> and ineffiecient.

I use Bobcad/CAM, definitely at the low end of the spectrum of CAD/CAM.
It has no difficulty with odd shapes, but then it has no 'concept' of part
OD, either. Everything on the screen is just lines, and only the user really
knows what it all means. Given a number of limitations, though, it can draw
a 3-D shaded picture of the finished part, so it CAN figure out that the
most remote lines must define the exterior. (Note that higher-end 3-D software

actually handles objects as volumes, and can add and subtract volumes.

> If I could draw the raw material to dimension roughly in
> the shape it is when I want to begin, oriented in the PLANE of the device I
> intend to use to modify that shape and can then define the finished project
> with the help of the canned cycles and drop down menus, lists, tool
> libraries, then all that would remain is to test cut a sample and see if the
> surface finish or sequence works to produce the product I want.
>
> I had a major guitar manufacturer asking me to quote on supplying parts.
> When I quoted him the cost he then asked me for a 12" x 3" x 1/2" tall slab
> of ivory, that he would put it in his fadal machine and machine it himself
> for a fraction of the cost. Again this is my point, the medium I work in
> does not exist in dimensions that are predictable or similar to buying a
> chunk of aluminum bar stock, So I have to be creative in fixturing,
> placement and aproach to part manuafacture all relative to the physical
> shape of the material. So if I am alone in my needs then I will live with
> it, I do think others drag home nice chunks of misshapen stainless steel,
> odd lot cut offs and any varietyu f shapes of things. Having two choices for
> raw material. rectangular or round, with round always being defalted to a
> lathe operation is a very serious limitation in designing and efficient
> reduction of material that costs $300.00 a pound or more.

I almost wonder whether you have missed some feature or menu that
allows broader generalities of shapes. I often machine rectangular parts
on my mill, but I also do round and curved parts, now that I have CNC.
It was one of the great improvements to my machining capabilities that
I could cut straight lines at any angle, not just parallel to a machine axis,
and cut circles and lines that have continuously joined straight and curved
sections. It sounds like your software is not capable of most of that.

One possible workaround is to go ahead and define a rectangle if the
software needs it, and then define your actual part shape inside that.

I don't have to have even a single line of wasted G-code when I use
Bobcad/CAM, as you can specify the starting point. The software does
not choose the starting point for you.

Jon