[Coco] Schematic for external PIA, cart protoboard.

[Gene Heskett]

On Saturday, February 07, 2015 12:22:06 PM Richard E Crislip wrote:
> On Sat, 7 Feb 2015 11:25:13 -0500
> 
> Gene Heskett <gheskett at wdtv.com> wrote:
> > On Wednesday, February 04, 2015 08:23:53 PM camillus.b.58 at gmail.com
> > 
> > wrote:
> > > As I remember, we used to have a pia controller board that just
> > > needed to be inserted. It had address selection and decoding, and
> > > some LED on one port while the other port was usable
> > > 
> > >  as input. Let me look to my stuff maybe I have some info still
> > > 
> > > laying around.
> > > 
> > > 
> > > cb
> > 
> > George Ramsower uses a coco or 2 to drive (slowly) some of his home
> > made cnc machines.  Perhaps he would be willing to share some
> > schematics of the interfacing he has built?
> > 
> > Cheers, Gene Heskett
> 
> That reminds me... have you heard of LinuxCNC? I saw it demoed Thursday
> night.

Naww, gee Richard, only since it was called EMC at 2.00 a decade and change 
ago.  Now its at 2.7-pre and running very nicely indeed. In terms of 
retrofitting machines to be cnc controlled, our free software has at least 
25% of the market and several are actually making a living converting 
machine that either have a dead controller or were manual in the first place.

The other 75% of this market belongs to Mach3, based on windows, and is a 
huge slow kludge compared to the direct access linux allows to the parport.  
Sure, we have a thriving market in interface cards for really high 
performance machines, but we can live without it on smaller slower anyway 
hardware.  Windows cannot, and IIRC Mach3 requires a special interface card, 
and of course a $175 licence.  Windows folks simply do not know any better.
This is good enough that a very fancy $200k machining center at the Toy 
factory in southern WV is using linuxcnc to drive that multiaxis machining 
center to carve, from a solid block of ALU, probably in the 7078-T6 alloy 
range, the racing engine blocks that Toy, just like Honda etc, rents to the 
big names in racing.  That is not widely known but there was at one time an 
nominally 30 minute movie on you tube showing both the control panel, and 
the machine thru the safety glass, carving it, truly a work of art as there 
was not a single surface in that whole completed engine block that was not 
machined, to .0002" tolerances.  One such block was about 4 hours being 
carved, and the swarf filters in the coolant system will have recycled about 
300 lbs of ALU cuttings from the original block of starter ALU alloy.  That 
stuff is tough even when shielded from the air so it doesn't oxidize near as 
fast, but that 4 hours also wore out a box of carbide inserts for every tool 
in its auto changer rack per block.

I have carved some stuff from solid ALU a lot softer than that, and its 10x 
as hard on tools as decent steel.  To really do a good job, you must arrange 
a spray of coolant that hits the raw ALU 10 thousandths of an inch behind 
the cutting edge that made it raw. 

Yes, ALU is a very reactive metal when exposed to anything with oxygen in 
it, forming an oxide film that is the 2nd hardest substance we know about, 
doing it in about 50 microseconds. The huge majority of the heat created 
when machining ALU is not from the friction of the cutting tool but from the 
heat of this instant oxidation as the raw metal is exposed to the air.  So 
tool coolants are mixed to have as little free oxygen as is possible, and 
applied, usually by a mist spray directed at the bottom of the tool so the 
ALU is re-wet and sealed from the air, as quickly as its physically possible 
to do.  Big machines like the one at Toy effectively run in a sealed 
environment, with coolant pumps capable of 1000 psi.  And the enclosure if 
well enough sealed, might even be flooded with dry Nitrogen gas to displace 
the oxygen.

Did I not show you the two machines in an outbuilding in the back yard when 
you were here?  If not, I really must be slipping in my old age. I better 
call the paper & put in an adv for a keeper in that case. ;-) I think the 
lathe has been converted after your visit though.  Ball screws , the whole 
maryann.  No hand wheels on it, its run, when running by hand, from keys on 
the keyboard, same as the mill has been for yonks, but it too now has ball 
screws in the table drives.  Not yet for Z (head up & down) but its accuracy 
is now in the +-1 thou range anyway with the aftermarket screw I do drive it 
with.  But its grown some brackets on both sides of the head casting that 
about triple its "wheelbase" by holding ball bearings that ride the post 
casting.

Cheers, Gene Heskett
-- 
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