Re: Two tools on a lathe-programming problem

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Ron Ginger <ronginger@...>
wrote:

>
> I was asked to help convert a large hydrauilc tracer lathe to CNC.

This

> is a wood turing machine that generally makes things like porch

column-

> up to 10 ft long.
>
> The basice machine would be a simple project, BUT there is one

item I

> cannot figure out. It has one carriage driven by a servo motor,

but it

> carries TWO cross slides. The slides are about 6 " apart. In

tracer use

> the leading cross slide carries a rough cut tool, the following

one

> carries a finish tool. In one pass (remember, 10 FEET long) two

cuts are

> taken.
>
> It would be simple to put a motor on each cross slide, but how

would I

> code it? There is only one controllable Z axis. At any particular

spot

> the two X slides need to be in different places. If I could build

some

> kind of 'delay line' I could delay all the x steps by the right

ammount,

> but that seems tricky.
>
> Is there any software that does this? I understand there are

commercial

> CNC lathes sold that can do this.
>
> Fred, can Vector do this?

Yes, it should be possible. If there is only one Z axis, I would
set the machine up with two X's with a Z offset ( X & U ), and use
the 4 axis routine to create X-Y-U-V code, then in the post,
substitute the appropriate axis letters as needed for your
controller and drop out the original U component(or the V, depending
on how you draw the offset) which will be synchronized to the Z
coordinate, but offset by a fixed distance between the tool tips.
The resulting program will have the equivalent of X-U-Z, with X and
U independent lathe X axes.

Make sure you leave clearance on the ends of your stock to start the
roughing and complete the finishing with the other tool hanging in
space past the end of the part.

Fred Smith - IMService
http://www.cadcamcadcam.com/hobby