Problem- HOW TO CUT AND ARC ACROSS AN ARC.

[NTI]

Does anyone know how to code an Arc (G17, G18, G19 or G117, G118, G119) and then run that Arc longways in the shape of an Arc? Like the shape of an old motorcycle fender...round side to side, and round end to end.

[beege]

That be called a torus, or toroid, if the one of the arcs isn't really an arc, or a spline. you could do some with a form mill, or on a lathe, or a rotary table of some sort... On a CNC mill it might be best to use a CAM package

[NTI]

I've gotten everything else done without having to figure out my Mastercam. Mostly simple stuff, granted but non-the-less. This one has stumped me though. I even thought of using the Repeat option on the old Shop-Floor program installed, and try to have it follow an arc instead of a straight line... but no.

[ProProcess]

Do you have some specifics?
How many degrees of the are are present along the "fender's" length?
How wide is the "fender".
How about a macro?

[NTI]

THE ARC LONG WAYS WOULD BE ABOUT 15" ALONG THE X AXIS AND ABOUT 45 DEG END TO END. AND THE ARC SIDEWAYS ABOUT 6" AND 90 DEG SIDE TO SIDE ALONG THE Y AXIS. FROM THE SIDE OF THE FENDER UP TO THE BLOCKS TOP SURFACE WOULD BE STRAIGHT UP THE Z AXIS. THE SIZE AND DEMINSIONS COULD BE ANYTHING BUT LETS ASSUME ITS WELL WITHIN THE CAPACITY OF MY MACHINE.

ISN'T A MACRO NOTHING MORE THAN THE SAME SET OF INSTRUCTIONS JUST IN A NAMED PACKAGE THAT CAN BE MOVE AROUND AMONG THE LINES OF CODE?

[ProProcess]

You could author a Macro that would break up the arc along the X axis into a line segment then generate the YZ tool path for each segment. A macro would allow you to define each segment's "Step Over" then and calculate and cut ect,ect...
Do you have a drawing?

[NTI]

So how exactly do I go about this. How does one break up the XZ arc into segments to attach the Macro to it, which I'm assuming would just be the YZ Arc G19 line code?

And No I don't have a drawing. This is more of a Seat of the Pants manuver at this point.

[ProProcess]

You have to have an intermediate understanding of Trig and Macro Trig functions. But in basic terms...

At the center of the arc along the X axis the Z depth will be at its deepest.
At that point you could figure your YZR tool path.
Then if you stepped over .010 in X you would use Macro Trig functions to figure out how much Z would stepup to make the propper segment. You would also need to factor in the Ball Mill size.
Once the algorithm was done, you could tweek the X steps to get it as smooth as possible. Doing it this way may be tricky in terms of generating a tool path that is always normal to the Arc along X but if this is "seat of the pants" I'm sure you could get something close.
HTH

[NTI]

So what you're saying, as "beege" suggested, there is no EASY way to do this, short of a good CAM program.

I was afraid of that.

Well guys, I guess you've answered my question then.

Thanks for the time and expertise.
Glen

[ProProcess]

You may be able to barter or pay for some CAM output from a local shop for minimal outlay...
Good Luck!

[Kiwi]

Not sure if this is what you require.
Attached is a VB program which can generate GCode for an arc.

[NTI]

I CAN'T REALLY TELL BY LOOKING AT IT. I'LL TRY A SAMPLE ON THE MILL AND SEE HOW IT GRAPHS OUT.

THANKS AGAIN,