Re: [CAD_CAM_EDM_DRO] VectorCam Demo and EMC - Lathe

Tom Benedict wrote:

> I've got a Taig CNC mill with the Microproto controller. I got EMC
> working fine with three axes (I'm having little to no luck getting the
> fourth axis working, but that's neither here nor there.)
>
> Last night, just for grins, I turned the mill head 90 degrees, mounted a
> lathe toolpost on my mill bed, and brought the spindle down until it was
> level with the lathe tool. In effect I made my mill into a poor-man's CNC
> lathe.
>
> I've got the VectorCam demo set up on a machine at home, and have been
> trying it for mill work. But I've been wanting to test it for lathe
> functionality, too.
>
> I ran into a problem. I'm hoping someone can help:
>
> I used a CAD package to draw up the profile of a ball handle (two arcs,
> one tapered straight section, and the second arc was cut short so it
> would leave the ball handle firmly attached to the stock.) The DXF
> imported into Vector perfectly. I used the lathe pocket function to set
> up a toolpath, saved it as NC code, simulated it, everything checked out
> fine.
>
> There were two problems when I tried to run it using EMC. One was my
> fault, one I'm not sure of. The one that's my fault was because I didn't
> know CNC lathes use X and Z axes. After some time reading Machinery's
> Handbook, I figured that out, swapped my motor plugs, and was back on
> track.
>
> That's when I ran into the second problem: The roughing passes went
> perfectly. The finishing pass died as soon as it hit the first arc. The
> error message was something like, "K word on an arc in the XY plane."
>
> Far as I can tell, the G-code generated by Vector is spot-on. It had an X
> word, a Z word, an I word, and a K word. The arc is in the X-Z plane, not
> the X-Y plane.

G17, G18 and G19 select the appropriate axis plane for arc motions.
I always forget which is which, G17 is XY, of course. From the EMC
help file, you need a G18 before that arc, to select the ZX plane
for the arc.

> Any idea how I can fix this? Is this an EMC thing? My EMC installation
> is off the latest BDI.

No, most CNC systems that support arcs in one of 3 planes require you
to define the plane before the arc.

> I'm probably not going to use my mill like a lathe very much (I'd rather
> build out a dedicated CNC lathe), but I'd like to go ahead and buy Vector
> next month, and I've got some short-run stuff I'll need to do with it in
> this configuration. So any and all ideas are much appreciated.

This should get you running.

Jon