[Coco] Wiring inputs to the Coco

[Gene Heskett]

On Sunday, January 11, 2015 10:49:21 PM Bruce W. Calkins did opine
And Gene did reply:
> Back in the '90s there was a series of articles in Model Railroad
> Magazine for an interface to run a model railroad with an 8 bit
> computer.  There were adapters for most of the popular 8 bitters and
> the CoCo was one.  I did save the articles, but have no idea if the
> components and circuit boards can be obtained today.
> 
> Bruce W.

That is not a problem with eagle.  That which I have needed was easy 
enough to draw up in eagle, and I've made several pcb's on my milling 
machine from eagles output once its run thru pcb2gcode. But with a 
spindle speed maxed out at 2500 revs, driving a V pointed etching bit 
thats comfortable at 150,000 revs, that speed limit enforces slow motion, 
so the typical 1.25 x 2 inch board for the position encoder on my cnc 
lathe takes around 4 hours to mechanically etch both sides.  I could get 
them done better at one of the board houses and not have to fight with 
the fact that I cannot do "Plated thru" holes.  I have seen & read 
several articles on doing that and all have involved environmentally 
dangerous chemistry.

But even so, there is a certain pride in being able to say I made it 
myself.

This board tells the computer where in the rotation the spindle is, with 
a 1.8 degree accuracy, and can do it at spindle speeds aproaching 5000 
rpms. With it, there is no limit other than the size of the single tooth 
cutting tool, to the number of threads per inch or millimeter I can cut. 
I just made a play takeup adjuster for the mill, using 1/2" A2 alloy tool 
steel rod in the raw un-hardened state, at a thread size of 1/2", at 40 
threads per inch, and bored  and threaded the place it went in the nut 
holder.  I could just as easily have made it 39 or 41, even 80 threads 
per inch, or 2" a thread, and there are NO change gears for threading in 
the lathe now, the spindle to carriage motions are locked together in 
linuxcnc.

Cheers, Gene Heskett
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