Re: Look-ahead

[Jon Elson <jmelson-at-artsci.wustl.edu>]

Dan Falck wrote:

> Please excuse my ignorance on this issue, but I haven't had to really push
> my machine on any 3-D work and I am curious about EMCs look-ahead
> capability.  Is there anyone out there who can tell me what kind of
> "look-ahead" or constant contouring ability EMC has?

Yes.  If physical memory on the computer permits, the look ahead goes
to the end of the program!  It has ALL the moves in the entire program
interpreted and planned before you hit the start button.  If the program
is very large (many hundreds of K, at least) then it will run ahead only
a few hundred K, and wait for the machine to catch up.  I haven't had
a program yet where the interpreter was not at the end of the program
before I started executing it.

> So far, I have done all 2-D profiles and wonder how EMC would do in
> sculpture and mold type work.  My mills' spindles don't run fast enough to
> do any kind of high speed machining, but I am about to mount a router along
> side the milling spindle on one, to do some carving.

I think EMC will perform fine.  I haven't done much of this work either,
but I have done some tests with a large number of extremely small moves,
and it just hums through them.  This had several places where there were
over a hundred vectors less than .001" in a row, and it just moved through
them in a second or two, with complete smoothness.

Jon