Re: Machine Options in CAM Software ?

>--- In CAD_CAM_EDM_DRO@y..., Jerry Kimberlin <kimberln@a...> wrote:
> Mark, a year ago more or less I asked the same question by
> wondering what a post processor was. I got some good answers,
> but nothing definitive from the development types.

A post processor is a small program, usually part of the cam program
that process your machining instructions into an ordered code the
machine in question uses.
You may have a simple machine where when you select a new tool it
justs stops the spindle to allow you to change the tool. OTOH on a
more complex machine selecting a new tool will write a whole series
of commands into the code to withdraw the old tool, move the table to
a position where it can be reached by the tool change arm and proceed
to issue commands to automatically change the tool. You edit the post
file when you get the program to suit your machine unless someone has
already done it for you. The whole idea of a post processor is that
the code produced goes straight to the machine without having to
fiddle with it.
If you have to edit anything in the code at the machine then your
post isn't doing it's job right.
For the home shop guy these are usually simple and are reseved for
automatically entering the start up, tool change and end routines.

A program with a well thought out post is very nice to use and it's
makes things simple. Dolphin for instance, takes the tool diameter
and automaticaly adds or subtracts the tool radius so you don't have
to bother with G41 / G32 tool off sets if you don't want.
A change of tool size will result in the post recalculating all the
moves and outputting the fresh code. With other programs such as
Bobcad which write on the fly using a configuration file as opposed
to a post, a change in tool size will mean a complete re-run of that
operation. If it's part way though the program that also means you
have to delete and stitch in the new bit which can and does cause
problems if it doesn't follow on.

John S.