On Friday 12 October 2018 20:58:46 andy pugh wrote:

> On Sat, 13 Oct 2018 at 00:03, Gene Heskett <[email protected]> 
wrote:
> >  Is there a way I can indirectly address this stuff
> > in gcode? Like passing it those two digits and appending it to the
> > lincurve.0.y-val to get the correct y-val-## address on the
> > lincurve?
>
> As often happens I have no idea what you are trying to do, but what
> you are talking about seems like it would need a custom HAL compnent.
> (these are not hard to do, if you know C. And C is possibly the
> easiest programming language to learn. This is definitively not the
> same as saying it is easy to use.)

pseudocode, at top of file

#<_y_val_00> = "00" (need string to get the leading zero?)
( whole list of y_val="01" etc
(copy/paste for x-val's, giving distance as 24.5 at about an inch from 
tailstock face. Followed by 18,12,9,6,4,4,2,1,0,-1,-2,-3 etc)

o100 sub
g53 g1 f20 z#1
s600m3
m1 (adjust offset with my circuit to match, say 400 ohms)
but on first run: 
hit esc and do an x touchoff to 0.000, then rerun.
m5 (let the spindle  cool, it needs another thou of shimstock under the 
front cap)
o100 endsub
#<_z_val> = 24.5
o100 call [#<_x_val>]
#<_z_val = 18
o100 call [#<_x_val>]
#<_z_val> = 12
o100 call [#<_y_val>]
#<_z_val> = 9
 etc etc, writing down the x-val and offset needed to keep it at 400 ohms
Eventually it will hit the spinning chuck, so a different laser mount 
will be needed before it gets to a Z=-1.

When  all the usable points have been recorded, hit esc, and edit the 
table into hm2_7i90-stepper.hal, rerun to see how much variation 
remains. It ought to be under .0005" to hold the 400 ohms at the cds 
cell as Z is run over its working range.

I am noting that I can see the high spots around the dings in the ways in 
the DVM reading, and have been very carefully polishing them down with a 
well worn 1200 grit DMT plate, but I think I have the major bumps down 
to a thou or less with the work I did today, which I started out by 
centering the tailstock with a fresh center in it, so the beam was 
reaching a bit over 1/16" down both sides of the tip as the spindle ran.

The cds cell, about 1/8" in active surface area is stuck in some 
modelling clay, stuck in the tailstock barrel and the clay adjusted to 
put the laser beam at a minimum resistance in the 250 ohm area with the 
full beam on it. Its not as bright as it would be on fresh batteries, 
but I can leave that 1.7 volt supply on for years for a few cents worth 
of electricity.

I am also going to vary the spindle rpm a bit in case I am too well 
synchronized with the DVM a/d, at 500 revs, the cycling is very visible. 
+-=50 or more ohms. 650 revs will tell that story.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>


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