On Feb 3 2013 10:21 PM, TJoseph Powderly wrote:
> EBo, your name rings a bell all the way back to Paul Corner EMC days,
> you been arounf here a long time i think

Yes.  Paul's nastiness is why I completely disengaged from EMC for a 
*very* long time.  It was the type of two faced - stab you in the back - 
interaction that the culture I come from tolerates a lot less than a 
literal punch in the face.  Interestingly enough I was being funded to 
work on EMC at the time, and could have focused on it 40+ hrs/wk, and 
the kerflufle caused me to just walk away...

If that history bothers you, I can easily bow out permanently.

> ...
>
> this constant velocity is totally unsuited to EDM, the finaly 
> mechanical
> driving element better to jiggly and nervous, else it aint repecting 
> the
> process
> uncover the final gear or screw on any real working edm and watch, it
> approaches a smooth forward motion but IS jiggly and nervous.
>
> ...

The EDM head I wanted to prototype, based on a some old work I saw 
once, has the jiggly portions controlled via analog circuitry in an 
internally closed-loop.  All I would need it to do is either output a 
pause, or an analog feedback that basically adjusts the speed overide 
from where the user sets it down to 0 (full stop).  That way it should 
be able to fully integrate into LinuxCNC.

BTW, I should add, that the EDM head I am talking about is a sink type, 
and is self retracting a very small distance, but all of that is handled 
by the head.  That is how the current V/C feedback is maintained.

> mydynac repairs cnc edm for a group in sugar grove illinois 'edm
> network' owned by Ron Vogel ( iirc)
>
> the work done more recently by Scott Haase in WI >can< reverse and is
> limited to an upper and lower bound
> (same as mine)
> his uses O-word gcode, mine is hal based ( limits sets by mcodes, and
> motion implemented thru 'offset' hal component )
> his o-word may be easier to debug, dunno, but for immediacy, hal 
> should
> prove mpre responsive because its 1 less layer of control

If I can find an old wire fed, or other industrial EDM, then I can see 
spending a lot of extra time on a project like this.

> and for the edm gap voltage -> arduino -> threshold comparison -> hal 
> ->
> motion loop of Mr Haase
> well there many layers removed by directly connecting a window
> comparator to a  hal 'offset' comp

If I do the arduino thing, it will be completely independent of 
LinuxCNC and not an addition to it.

I have some experimental code I wrote over a decade ago, when I was 
taking PhD level courses in Computer Aided Geometric Design, which 
converts standard G-code into an abstracted motion splines.  The intent 
was to eventually implement the low level as a NURB, but started with 
Bezier splines because I had several implementations of them at the 
time.

Part of that design was to incorporate a fully runtime polymorphic 
parser (which allows you to overload things like how comments were 
handled and different interpretations of the g-coded standards -- which 
allows you to run very old g-code for a machine without modification on 
a more modern machine/retrofit).  All of the last part could also load 
user definable modules at startup, so you would not have to 
recompile/reconfigure the program to use different constructs.  Anyway, 
I let that effort fall by the wayside...

> <out of sequence>
>
> the idea of orbitining is to use the distance moved away from the
> 'roughing point' to feed a sine and cosine generator
> and use that value to move X&Y along the surface of a circular cone. 
> As
> the Z motion increases, the circle increases ( and drops )
> if the process sees a redcuced input signal , ALL axis collapse to 
> the
> that 'roughing point'.

I will have to think on this.  I can see that it could be used to 
produce a similar effect to adaptive clearing (and share the tool ware 
over a much greater area).  For the moment I have no interest in this, 
but I can see the benefit of the functionality.

   EBo --



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