Re: [CAD_CAM_EDM_DRO] Good CNC Book?

rawen2 wrote:

> Hi Group,
> I have to travel for a couple of weeks for work and dug out an old
> text book that I've never read to take with me. It's
> called "Computer Numerical Control, Concepts and Programming" Third
> Edition by Warren Seames. It's copyrighted 1995. I'd been taking
> evening machining classes at a community college when I lived in CA.
> When I got through the required manual machining classes and was
> ready to take CNC I changed jobs (late 1995)and moved to Portland,
> OR. Had already purchased the book for class but had to cancel my
> enrollment.
> My question is this: Do you think this book is too old to do me any
> good?

No.

> Technology changes so quickly that I don't want to get
> confused by reading outdated material.

RS-274 (alias G-code) was standardized in the 1960's, and revised for the LAST
time in 1974 (RS274-D). Every machine control maker has their own variants
of G-code, but it is essentially unchanged since then.

There are some newer methods of specifying smooth surfaces and doing 5+ axis
machining, but the basic G-code is not changing very quickly at all!

> I briefly glanced at it and
> appendix 3 is titled "Codes in Common Use with Tape Machinery".
> Wow. Sounds like "Troubleshooting your car's 6 volt generator".
> Another appendix is titled "EIA Codes".

The EIA character code predates ASCII, and is essentially dead. many older
controls can still handle it, like my Allen-Bradley 7320. It looks at the first
character on the tape, and figures out what character code is being used, and
then knows how to read the rest.

But, the ASCII code we all use, as in this very message, is pretty much the
standard code used now. (note that EIA could be used with 6-channel
wide paper tapes, you need at least 7 for ASCII, or 8 if you have parity,
which sounds like a good idea for machine tool programs.)

> Would these be pretty much
> equivalent to the NIST codes that EMC and Mach1 are based on?

EMC definitely supports the ASCII codes, whether from paper tape or
IBM PC.

> I
> don't know how much G-codes and programming practices might have
> changed since the mid nineties. I know the hardware (computing) has
> advanced light years.

I learned much of my G-code from working with Allen-Bradley manuals
when I got my A-B 7320 working.

Jon