[Coco] SysCall source listing

[Gene Heskett]

On Wednesday 27 November 2013 13:19:32 Wayne Campbell did opine:

> Fishing?? I think I heard of that somewhere. Let me think...
> 
> Oh yeah! That thing that looks like a whip stick with loops on it and a
> string running through it? I used one of those things once. I thought I
> was going to die from the boredom. Of course, I was only 17 at the
> time, and fishing was not on my list of important things to do, like go
> where there were girls and stuff. Maybe I should think of revisiting
> it. First I have to retire from working on things and volunteering my
> time. I use alot of time doing those things.

There is that too, but its called hobbies in some circles.  But you are 
still in the 'working' class, not old enough for SS yet.  Me, I build a 
piece of furniture from time to time, and have converted a 7x12 lathe to 
full CNC control with a 6x heavier spindle motor and ball screw drive, so 
the accuracy, under computer control is about a thou.

And a small tabletop square post mill with 4 axis's of motion with numerous 
improvements, but no ball screws (yet) that can work to about a thou 
tolerance in the 3 basic moves, and a cheap, sloppy rotary table can be 
mounted on the XY table and controlled to small pieces of an arc second if 
the cutting forces do not cause it to take up its backlash of perhaps .2 
degrees depending on the exact position of the worm and bull gear since 
they both have a bit of eccentricity, perhaps .0005" each that I haven't 
managed to wear in, yet.  Cheap India made, only $110 at grizzly.

Current project for it, is mounting an endoscope camera ($22 + ship, ebay) 
looking straight down from a position on the side of the spindle carrier Z 
axis housing, which will eventually replace my present method of locating 
the back side of a pcb I am milling, by drilling 2 holes all the way 
through the board in unused edge locations, recording the positions by 
moving the XY table to put those 2 holes exactly at the cameras crosshairs 
so that the difference when the board is turned over and the same 2 holes 
measured and recorded again, can be used to calculate the offsets needed to 
locate the backside of the boards co-ordinate system, all with nothing more 
than a series of mouse clicks.  The target is, as I can do now with a much 
more labor intensive procedure, to be able to drill a parts lead hole, 
halfway thru the thickness of the board, turn the board over and drill from 
the other side with the holes meeting in the center of the board thickness 
with undetectable offsets,  straight thru IOW.

Currently because I am using electrical contact between the inside of a 
small brass pipe inset into a corner of the board, or to the copper of the 
board itself and the cutting tool to do a lot of this auto positioning, but 
it demands I make an insulating micarta pallet to hold the board that is 
cut on the bottom with a hold down slot (in the X table) fitting "fin" so 
that it cannot rotate should I remove it and remount it later, then turned 
over and a pocket milled to fit the board, then drilled & tapped for a 
bunch of flat head 0-80 screws to both hold the board flat, and to wedge it 
against the 2 sides of the cutout (the board itself needs to be filed such 
that it fits the cutout with no more than 2 or 3 thou slop) so there is an 
absolute reference from an arbitrarily established rear edge, and the same 
edge of the board when its turned over to do the other side.  This bit of 
pallet making tomfoolery takes about 2 days to do when the board size 
changes by even 5 thou.

All that can now be nothing more than a micarta pallet that can be mounted 
on the table without any great regard for how square it is to the table and 
its motion, and with only 2 reference edges machined in the pallet to 
locate two edges of the raw board, and its turned over and the same 2 edges 
are pushed back into the v-pocket, re-clamped and the camera used to 
determine the corrections needed by measuring where those 2 holes are when 
turned over.  The board still needs to be insulated of course, so the hold 
downs will still need to be insulated.  But I won't have to make a new one 
for each board.  Even the 2 thru holes can be drilled by the same technique 
by locating the hole in the bed of the pallet, and going backwards with the 
offset so the drill bit doing the drilling will re-enter the same hole in 
the pallet bed.  But that hole has to be cleaned up some as the act of 
drilling rises a rim around the hole which would then hold the pcb a couple 
thou high, screwing up the actual etch operation by making the bit carve 
too deep.  So, we drill that first pair of holes, then mill the flat bottom 
of the 2 sided pocket which solves that problem by removing that rim.

I am totally blown away by the some of the idiocy I see on youtube where 
the guy is using a std small jacobs chuck to hold his etching bit instead 
of a well fitted collet, (that alone allows a 3 sided wobbling as the bit 
turns) by running his machine to an arbitrary point above the board, 
loosening the chuck and letting the bit drop to contact the board, 
tightening the chuck and then carving or etching the board to whatever 
depth his software drives it to, totally oblivious to the fact that 
tightening the chuck is done by driving the jaws lower, carrying the bit 
with them as much as 10 thou.  Then you look at his result, and the ditch 
in the board is obviously a long ways into the fiberglass below the copper.  
Among other side effects, dulling his $10 solid carbide bit 30x faster than 
if he was only removing the copper.  Copper is easy on carbide, fiberglass 
is not, so the bits tip shouldn't go more than .0002" below the copper, 
that much, on the micarta pallet, and it will just slide without actually 
cutting the glass.  But you must have both precise machinery, and equally 
precise methods of measuring.  Electrical contact gives me 10x the accuracy 
the machine is capable of, sub-micron when the applied voltage is only 5 
volts.

The only thing dumber is our current political situation, but thats OT for 
this list.

Once I get this working, then its time to consider a method of doing the 
thru hole plating of a double sided board. So far no clue at the chemistry 
involved in that. YAP, eg Yet Another Project, if I have time enough left 
to do it. ;-)

About 1.5" of wet snow here, more forecast.  Survival goodies on hand for a 
2 or 3 day siege, but both vehicles are 4wd, std issue in WV.  My now 
rusted out 99 GMC pickup is usually referred to around these parts as a WV 
Cadillac.  I twist the key, it takes me where I want to go. :)  Chains for 
all 4 corners that haven't been on the ground more than 4 or 5 times since 
I retired in 2002 are under the 3 door cabs foldup back seat.  Bring it on!

[...shorter years]

Cheers, Gene
-- 
"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>

A small town that cannot support one lawyer can always support two.
A pen in the hand of this president is far more
dangerous than 200 million guns in the hands of
         law-abiding citizens.