[Coco] Electronics Newbie question

[gene heskett]

On Sunday, December 18, 2011 10:05:35 AM Andrew did opine:

> Paulo,
> 
> This should probably be a separate thread, but anyhow...
> 
> Typically, many people recommend Eagle:
> 
> http://www.eaglecentral.ca/eagle/
> 
> It's only real downside (other than being "non-free" - that is, non-open
> source, if that matters to you in any way) is the fact that to go beyond
> a certain basic level (which you may or may not ever need), the license
> cost climb into the stratosphere very quickly; however, I've been
> assured by others that if you are using it for commercial purposes, to
> design and sell PCBs (or kits, or products), that you'll recoup the cost
> fairly quickly.
> 
> If you wanted something more "open source", then there are options like
> KiCad:
> 
> http://kicad.sourceforge.net/wiki/Main_Page

Which ATM, has some real show stopper bugs.  Skip it.

> ...and gEDA:
> 
> http://electro.easyb.ch/pages/schem.html
> 
> Note that gEDA has a very, very steep learning curve (not that Eagle is
> going to be easy, from what I understand). I don't have any real
> experience with any of these packages, but I have looked at them all
> from time to time. They all have their pros and cons, IMHO.

As you say gEDA has a very steep learning curve, but isn't limited by much 
except your imagination.  And I believe one of its options once the pcb 
layout is completed, is to output the thing in mill away the copper format 
that with some slight editing, can be executed by EMC to carve a working 
pcb by cutting away the outline of the trace. Looks odd because there is 
often dead copper between the traces, but works well for stuff that doesn't 
get above a few dozen megahertz. But because of the learning curve, I have 
not yet created anything with it.

Because of environmental concerns, milling the pcb is the only real option 
for the hobbyist.  Milling it is too slow for production use, but it is not 
an environmental disaster either, which is why 99% of the adds you see 
where small boards are done from your files, say 5 for $49 are all offshore 
fab shops.  The main problem for milling is the spindle speeds available, 
we get maybe 2500 rpm where we really need the 200k rpms an air driven 
dental spindle gives.  So we need super sharp mills and lots of time.  
Copper would rather push up a ragged edge than cut clean if the tool isn't 
10x sharper than your razor blade.  They aren't cheap either, and the edge 
is gone instantly if the tool actually carves into the board material.

Re eagle, the free version can't output anything in the way of a data file 
that I can use to carve a 1 off pcb board, possibly the $2500 version 
could, but I'm not $2500 worth curious to get the ability to carve a 3/4" 
by 1.25" pcb. I won't go into the details of getting to an etched PCB other 
than the extreme difficulties of disposing of the used etching solution, it 
absolutely cannot be poured down the drain, not ever. Don't even think 
about it.

IMO, a $250 version that only output .ngc code for emc would be the true 
killer app for someone needing small accessory boards, like say 3 opto-
interrupters in a pattern to read encoder wheels on the spindle of a lathe 
or a milling machine which opens up the possibility of doing rigid tapping 
more precisely than the common change gears allow, whose accuracy is 
severely limited by the various sources of backlash in the mechanics.

All that can be measured and compensated for in EMC.  But first we need to 
know where the spindle is in its rotation to an accuracy of a degree or so, 
in real time, at 2500 rpms. Eg every 6.66666666667e-05 seconds.  This of 
course doesn't apply to carving pcb's, but would facilitate other 
capabilities of the machinery.

OTOH, even $250, which may not be enough given the support headaches for 
eagle that people like me can generate, probably isn't enough for cadsoft 
to live on, and at the same time, $250 would be considered out of reach for 
the hobbyists among us.  No real price point where both can be happy.
 
> Finally - a "fun" option (not sure what the status of it is; last I
> played with it, it was still "buggy", but showed a lot of potential):
> 
> http://fritzing.org/
 
This one looked interesting, but when I went to dl it, the 32 bit linux 
choice shown was reported as not available.  Try again later...  The 
realtime autorouter was a nice feature, if you can tell it the mounting 
holes for the board can be in totally arbitrary positions, likewise the 
actual part mount location s/b completely arbitrary.  Much such pcb 
software is very tightly constrained to a pre-defined grid pattern, and for 
such as opto-interrupters where you need 2 looking at the same circle of 
holes in the encoder disk, to get truly quadrature performance, the opto's 
must be individually position adjustable to get the proper detection 
sequence which multiplies the accuracy by 4 as all 4 hole edges are used, 
so a 90 hole disk can give 1 degree accuracy.

Anyway, I was willing to download it to check this out, if I could have. I 
will certainly go back and retry.

gEDA I have had, but not on this pclos install so I've not looked at it in 
about 18 months.  Development of gEDA was quite active though.

> Something to keep your eye on, anyhow...
 
Yes, definitely.  The fritzing starter kit seems pretty arduino oriented, 
nothing wrong with that, but may be a profit center for them at 69 Euros.  
Current dollar conversion I don't know but likely about 100 bucks.  Most of 
that stuff is available at reasonable prices here in the states.

I should also mention HeeksCad/HeeksCNC, which is incomplete and users are 
encouraged to look at FreeCAD now, but the emphasis there is on mechanical 
fab & electrical is not well supported.  But one can do, from what you see 
& compose on the screen, exactly in metal or ?? with those apps to an 
accuracy exceeding your machinery's ability to carve.

> -- Andrew L. Ayers, Glendale, Arizona

Cheers, Gene
-- 
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