Homebrew PCBs

In a message dated 12/7/2006 6:24:44 A.M. Central Standard Time,  
rwskinner@... writes:

What  do you reckon a person could build there own PCB Drill for, if they had 
to buy  all the components?



If you have the TIME to read through hundreds of "ad pages" in  magazines and 
buy and try steppers and hardware offered, and have  patience to live-over 
having wasted much money, and you are a VERY good hunter  of such goodies, you 
might cobble something almost-useful for $1000.  But  if you want to have SOME 
success within weeks of beginning, so buy KNOWN-USEFUL  steppers and good 
drives like the Xylotex or Gecko drives, and can design a  decent buffer PCB with 
at least a 74HCT541 and preferably a 74HCT02, etc., for  "motor-on/off latch," 
etc., and want it to WORK well, you will need at least  Bishop-Wisecarver 
rails and ball-bearing "V-wheels", and/or Thomson or equiv.  linear ball bearings 
and hardened round-ways, and know HOW to mount all that  properly.  You will 
also need some decent quill-motor like a Proxon, or, if  you are creative, a 
400 Hz. 3-ph. motor with 1/8" collet/nut on its shaft, VERY  precisely mounted 
to that shaft, and a 400 Hz. inverter circuit to power  that.  But this 
high-freq. approach DOES take some experience with  things-electronic, though the 
result is FAR superior to a "brush motor" (aka  "universal motor").   Also, you 
can get away with GOOD ACME screws and  PRELOADED Turcite (glass-filled 
Teflon) nuts from one of the "precision screw  makers" like Ball Screws and 
Actuators or a couple of others, names I cannot  recall as I have never actually used 
other makes of screws.  
 
Plan on using excellent cabinetmaking expertise and Baltic  birch plywood for 
the carcass, and preferably light-colored Formica for the top,  so 
double-stick "poster tape" will work well thereon, without doing  damage.  It takes some 
years of fiddling with such to be able to cobble  something that works OK, if 
you are just beginning to brew your own such  machinery.  
 
After all that, if you do not waste and build efficiently, you  might do it 
for less than $2000.  I am envisioning "about what I have in MY  PCB drill", 
and what I'd do differently, were I to do an all-new one, and I am  CERTAINLY 
not including all the "learning expenses" of 35 years of  home-brewing.  
 
Carbide PCB drill-bits INSIST upon slop-free movement, and  logic that 
ENSURES the drill is UP and STEADY before moving to the next  X,Y begins, and STEADY 
for  drilling.          Jan  Rowland


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