Re: [CAD_CAM_EDM_DRO] What is EMC ? part II

riet91@... wrote:

> Thanks to all of you, specially Jon, Tim , Fred Procter, Matt Shaver
> ( whose two year old posting helped me a lot),Paul and all the others
> who are maintaining such a great forum and have contributed so much
> for EMC.
> Jon, I visited your site and the site you recommended these have
> helped me a lot to understand EMC, but I still have some questions :
> is the downloadable BDI at www.linuxcnc.org the latest one ?

It is probably running a month behind. The newest development version
at sourceforge is usually experimental, so you don't want one that fresh,
anyway.

> how much
> programming knowledge (and in which language) and knowledge about
> Linux do I need to start with EMC?

With the BDI CD, you really don't need much knowledge of programming
or Linux. EMC is pretty much all C and C++ except for the TkEMC GUI,
which is written in TCL.

> Has anyone used EMC for Turning
> center or Lathe? What and how much changes will be required for using
> EMC for Lathe control?

If you don't need to do threads, it is trivial, and everything is there.
there is a
discussion going on (again) about whether a spindle encoder for threading
is supported or not. It was, at one time a LONG time ago, before the port
to Linux. I don't know if it is supported now, but there have been 2 people

who seem to be doing threading on lathes with it!

> Does EMC support spindle speed control which
> is required for threading in turning centers?

Do you just mean adjustable speed, or do you mean constant surface speed?
Adjustable speed is there, for sure. Constant surface speed is probably not

that hard to do, since it doesn't need to be exact.

> One of my friend have
> Hurbert Churchill's Turning center who's GE's control is dead and we
> want to change it with EMC, one of the main problems I see is that
> the motors are 3 phase AC and I haven't found any cheap source of 3
> phase drives/amplifier, please let me know if anyone knows. I am also
> trying to make my own drive using HCTL1100 and IGBT bridge but this
> is on paper only,I haven't tried it yet.

Yikes! There is a chip from Micro Linear, the ML4423, that puts all the
control
into one chip. 6 transistors, fet (or IGBT) drivers and about 20 passive
components does it all. There are also some 'kits' from Intel and Motorola
that use their micros for this purpose.

But, the simplest (and probably in the end, the cheapest) solution is to buy

an off-the-shelf VFD for the HP and voltage motor you have, and be done
with it. I bought a 1 HP 240 V Magnetek VFD (brand new, dealer sample)
on eBay for about $180. It is excellent, and I'm very happy with the way it

runs. I haven't actually hooked the speed control up to EMC yet, but I
intend to do that sometime.

Jon