Re: [CAD_CAM_EDM_DRO] 4th axis rotary with a 3 axis control (and other tricks)

Ballendo, (and/or Fred and others)

This "fake" way does get one a 4th axis a cheaper way! It's like the
"rings" thread we had earlier (wish I had the rotary table now ;>)).
But I like learning what the "BIG" programs do. Art and I (and others
writing code) can benefit from hearing about the "big guys". Never
know, might even get in code for a lathe ;>)

OK, now I have a real simple *NEWBE* question, I've got the part
designed, and I can generate a "tool path" around the part's outline,
but it occurred to me, this part is .625 thick, and nowhere square (it's
an eccentric follower, 1" dia on the bottom, .63" dia on top of a "pear"
shaped part, 1.69 overall). The part has a .75" bore through on the
bottom end, and two ears with a .25" bore through them at the top, both
top and bottom bores parallel (.JPG on request).

HOW do I hog it out of a 1" x 2" x 1" thick piece of brass? I
understand how to do a pocket with an island (which this is not), but
how do I plan the cuts to remove all the outside? I really don't want
to just plunge down and cut the outline of the part out directly on the
Sherline. I thought about cutting around the part as if it were an
island in the raw stock's outline, but that didn't quite work out with
the pocketing command, that I could see.

I'd rather it was cut as series of "bigger" outlines, that gradually
worked their way into the brass block (easy intrusions into the edge of
the block). Do I have to just plan a set of bigger and bigger outlines
(tool paths), and slowly work my way down? Is there a standard function
to do this? I studied Vector's pocketing command, what would you call
this? It would be tough to cut the outline by hand on the mill, I've
probably only cut straight lines manually up till now!

Thanks again,

Alan

ballendo@... wrote:

> .......cut
> If we set up a rotary table (commercial,sherline,emco,msc,etc.)with a
> stepper motor. Or just use a strong stepper by itself!(prob'ly need
> some gearing or belt/pulleys if the work is of any diameter at all.)
>
> Mounted at right angles to the mill table (axis of work aligned with
> the X axis, makes it an A(technically, but we're gonna do a work
> around).
>
> Say we want to put a part number(or engrave a picture) on a cylinder
> mounted as described above. We only have three axes to work with.
>
> Plug the (4th axis) rotary described above into the "Y" axis driver.
> Now the rotary gets the "Y" steps, X and Z work as always.The trick,
> and its not really a big one, is to set the "Y" steps so that the
> rotary (tangential)distance has the same effect as the linear
> distance Y had before. Then this will work with any program
> previously written for XY on this machine!
>.......cut