Re: [CAD_CAM_EDM_DRO] Replace Heidenhein w/ EMC?

Jon Anderson wrote:

> Have a good friend, an auto mechanic, that loves machining and I've been
> helping him put together a machine shop for play mostly. (though we are
> discussing some ideas for products and a mutual mfg venture)
> When he wanted a CNC mill I suggested finding a dead Boss controled BP
> and refitting with Ahha as about the cheapest and fastest way to go.
> Then one of my customers decided to get rid of their CNC mill at a
> giveaway price, $2800 with tool holders and CAM. I don't recall the
> exact model control, but it's a Heidenhein control in a honkin' huge
> box. Down the road he'd like to go to a PC based control, and I
> mentioned just having recieved the BDI disk.

Hmm, most Heidenhain controls do not support G-code, but use their
own proprietary language, which is supposed to be good, but not
standard.

> Would like to know if EMC is capable of giving roughly equal performance
> in terms of speed and accuracy.

Same or better! The computers in these old controls were slow, and
the servo update cycle was usually quite slow (60 - 100 Hz). I'm running
1 KHz servo cycles with a 100 MHz Pentium Classic, and could go faster.

> Existing machine (Wells Index) uses
> linear scales in addition to motor encoders, can EMC use these as well
> or should they be offed with the Heidenhein control?

Hmmm? Linear scales AND shaft encoders? That is unusual, are you
sure? EMC does not really have any provisions for 2 separate measurements
of axis position. Is it possible there is a tach on the motor, not an encoder?

> This is a no-hurry project, probably take the two of us a year to figure
> out the interface issues... Just want to know if he's going to be able
> to rapid and feed at roughly equal rates to what he has now, and if not,
> how much will he have to give up?

The CNC control is not responsible for feedrates (in a servo system).
It is really up to the capacity of the servo amps and motors. You may
be able to continue using the servo amps, if they prove reliable.
The block processing rate almost HAS to be improved with EMC.
My old Allen-Bradley 7320 control had a block processing rate of about
4 / second, EMC does up to about 20 on the 100 MHz Pentium.

Jon