Re: ARC's, IKJ & R in Vector CAD/CAM, Art's program

Thanks Fred,

Sounds like the "better" controller programs will ketch the radius miss
match errors. We had a question on connecting rods a week or two ago,
possibly on the Sherline list, where the wanted radius was almost 40"
(2" part). Being able to flag the errors BEFORE cutting would be a
plus. I don't get any errors out of my current controller! It was fun
to check out the connecting rod .DXF on Vector CAD/CAM, and see the code
generated for the 40" radius, something that wasn't obtainable
manually! I had edited a file manually, and had a typo on an arc, my
controller went nuts! That's the stuff I'd like to get warnings on.

Best Regards,

Alan KM6VV

imserv@... wrote:

>
> --- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
> > Yeah, it probably wouldn't hurt to cut two complete circles, in
> opposite
> > directions, but I imagine doing G02 AND G03 back to back for LESS
> then a
> > full circle would cause problems! Probably fail because of the
> wrong
> > radius? Is there a practical limit or ratio of radius length to
> > start/end to determine a radius error?
>
> Absolutely not. You can cut any combination of arcs, both ccw & cw.
> As long as the end points are correctly stated and either the R's or
> IJK's are also correct. Many controllers will error if the arc
> calculation is not within .0001 inch. Some of the older ones had
> this requirement, but did not round correctly, so about 1/150 arcs
> has to be slightly modified to accomodate the fact the 1.00015 was
> rounded to 1.0001, instead of 1.0002. They did the math in hardware
> and that was the way it was. More modern controllers, especially
> those that are software based, will often have a tolerance that can
> be set. Keep it tight though, as a start and end point that are the
> same will generate a circle, even is you just wanted to make a tiny
> move!
>
> Some controllers do have a limit on the maximum size of arc that they
> can process. I have seen some in which any arc over about 40 inch
> radius was rejected(maybe the old Bandit controllers?). That is one
> reason that the arc-spline in Vector has a setting for max radius
> when fitting arcs to splines.
>
> Best Regards,
>
> Fred Smith
> IMService
>
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