Re: Can You Machine NURBS?

Hi Matthew,

While I've heard of NURBS, I hadn't heard of "NURBS G-code". What are
the specialized Gcodes involved? do you have a sample and/or a
reference? I'd thought it might be neat to do an "ellipse Gcode", but
then I don't cut many ellipses (or parabolas!)!

Alan KM6VV


"mjf462001 " wrote:

>
> NURBS stands for Non Uniform Rational B-Splines. It is a way of
> discribing a complex curve by math equations. Simular to splines.
>
> If you have ever milled complex flowing curves (not a true arc) and
> tried to do it with precision you notice that the post files can get
> very large. The reason for this is that most cnc controllers can only
> interpret straight lines and arcs/circles.
>
> The really neat free flowing curve that you drew in your cad/cam has
> to be broken up into really small lines or arcs to approximate the
> original curve. So besides the really large post file you still are
> not going to be able to machine the exact shape you drew. But you can
> get close.
>
> NURBS interpreters (CAD/CAM) will allow you to draw those artistics
> shapes and import the math equation directly into the machine
> controller. It is then up to the controller to calculate the cutter
> path. It only takes a handful of lines of NURBS G-Code to describe a
> complex free flowing curve. There are two advantages to this, you are
> able to machine the exact shape you drew, and the post files come out
> of the CAD/ CAM with a 60-90% reduction in size.
>
> If you have ever milled a curve consisting of lots of small segments
> you know how taxing it can be on your machine. The surface finish
> also suffers from these small jerky movements.
>
> Hope that helps
>
> Matthew