Re: [CAD_CAM_EDM_DRO] Re: Need some help!

stevenson_engineers wrote:

>
> >--- In CAD_CAM_EDM_DRO@yahoogroups.com, Ed Fanta <atex57@m...> wrote:
> > Hello all, I am looking for a recommendation for CAM software for
> >cams.
> > This is a rather odd cam in that it is what I call a straddle
> > cam. Imagine a cylinder with its axis pointing left and right,the
> >cam
> > action is created by a rib that goes around the
> > circumference of the cylinder and "moves" left and right as the
> >cylinder
> > is rotated, this in turn pulls cam rollers along
> > parallel to the axis of the cylinder. It would be relatively
> > simple if I could use a cutter of the diameter of the cam rollers
> > to eliminate sine errors but alas the machine isn't big enough. The
> > machine I am using for this is 4 axis and running EMC. Any help or
> > references gladly accepted. TIA. Ed.
>
> Is this what you mean Ed?
>
> http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/rotary%
> 20cam1.jpg
>
> If so this was done in Dolphin. Although small this was done in three
> passes as the cam track was 7.2mm wide. One track central at 6mm and
> two side passes offset to 0.6 mm to clean up.
> Dolphin will automatically do the tool offset allowance so all you
> draw is the one central path.
> We regulary do these for racing motorcycle gearboxes with no problems
> or scrappers.
>
> John S.

The picture shows a female groove, what this cam has is a male ridge
sticking up. The problem is you cannot use a simple offset to get the
width of the ridge, as the cam turns the width is affected as the sine
of angle. A simple way to see it is to clamp a stick or small board
horizontaly between your fingers then move one end up and down, your
fingers move apart according to the sine of the angle. Ed.