Re: [CAD_CAM_EDM_DRO] Creating long straight edges (and big squares)

Carlos Guillermo wrote:

> Hi Marcus -
>
> Just curious about your .0025" of wear - can you actually measure
> the effect of this on your parts? I had an old Southbend with a
> good .020" wear on the busy part of the front vee, and it really
> only bothered me on small diameter cuts. I would guess that the
> horizontal component of this kind of wear decreases as the cut
> diameter increases, as long as it's just vertical wear from the
> carriage going back and forth. What's your case?

If your front way has much more wear than the rear, it causes the
carriage to droop at the front, pulling the tool away from the work.
If the front and back Vee are worn equally, it will be as you say, a
minimal effect.

My 15" Sheldon lathe had .013" error on the front Vee, and .002" on
the back, flat, way. I'm not sure if this is a lube system problem, a
swarf grinding effect, or completely due to the vector forces on the
sides of the Vee. I was amazed to see such a difference in the wear,
front vs. back.

I calculated that this wear pattern would cause a .016" movement at
the tool point when turning a 1" diameter part, therefore it would
swell by .032" in the middle! That would be totally unacceptable for
the stuff I do.

Jon