Re: [CAD_CAM_EDM_DRO] reprap build started

On Tue, Oct 11, 2011 at 9:56 PM, Jon Elson <elson@...> wrote:

> Mike Payson wrote:
> >
> > There is a Z axis, how else would you move p by that layer step size?
> >
> OK, but the Z, or layer step, doesn't have to be programmed like the X
> and Y. It just steps
> down the same increment every time it is called to do so. But, it would
> be convenient
> to know what level it is at, so probably should be left as a controlled
> axis.
> > Granted the Z axis doesn't move much on most prints, but it is there.
>

I suppose it is possible to have a system that moves up and down a notch at
a time instead of using a leadscrews as it does now, but then you would be
locked into a specific layer height. Would make for a much less flexible
system, and I don't really see any benefit. Not to mention that some people
use the same controller to drive cnc routers, etc., which do need Z to be
able to move freely.

> >
> > the extrusion rate is done all in g-code already, we use the E axis for
> the
> > extruder.
> Unfortunately, E is not a valid axis word in strict G-code (RS-274D).
> EMC2 allows
> XYZ as primary linear axes and UVW as secondary linear axes. ABC are the
> rotary axes.

LOL, MUCH that the RepRap project does is not according to any standard. It
is largely irrelevant, since 95%+ of people use dedicated controllers, and
the few who don't could easily either modify the slicer to use a different
letter for the extruder or run a post processor to change the axis letter.

There is much to be said for sticking to standards, but there is also good
reason to occasionally abandon them when they don't really gain you
anything. In this case the latter seems reasonable to me, since "E" makes a
far more logical axis name for the extruder than "U".


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