Re: [CAD_CAM_EDM_DRO] Re: what is POSTPROCESSOR? a fundamental question

Jerry, the post-processor takes the required generic machine actions and
translates them into machine-specific G & M codes. For example, a FANUC
based machine will use G02 and G03 for CW & CCW arcs & circles, whereas my
SHARNOA uses G12 and G13 for the same function. (Actually, mine is a little
more complex, but it allows me to do helical milling with just the G12 or
G13). I do have G00 and G01 for rapid & feedrate recti-linear moves, but I
also have rapid and linear moves available in Polar co-ordinates, G10 &
G11! Also, my system requires a 'look-ahead' function for cutting into and
around acute angles. That way, your toolpath may be shortened.
Manufacturers each have their own ideas as to just how to represent the
required moves in G-code, and they're all different (and each thinks 'his'
is the best). They'd rather a Company only bought *their* machines, and if
the code was all the same, it'd make it easier for a person to jump from
one machine to another. Bottom line, you need a post-processor for any
machine that doesn't use the prescribed RS-274 codes. And,. I don't know of
any nowadays that still do! If you're building your own machine, you can
decide how to implement each requiired action, and maybe not have to use a
post processor.

RayHex

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> From: Jerry Kimberlin <kimberln@...>
>

snip>

> I've been trying for at least 2 years to figure out what a post
> processor does and have had no joy. Fred Smith has come the
> closest, but the explanation is still too generic and ambiguous.
>

snip>

> So far, no one on this list has explained what a post processor
> actually does; I've asked at least two times in the past 2 years
> about post processors.
>
> So let me ask a specific question starting from the machine end.
> If you have a Sherline and a Taig mill and each are driven with
> size 23 stepper motors of the same brand and lot number, then how
> is a post processor for each different? Probably not different.
> So lets say that both machines have steppers driven via Gecko
> drives. Does that change anything? Probably not. So, say the
> Sherline has Gecko drives and the Taig has Xylotec drives. Does
> that change anything? What I am after is the point at which the
> machines become different and why?