Hi Ed,
Thanks, but is there any chance I could persuade you to do a close
up photo showing a lot of detail.
Thanks!
Much appreciated.
Chris
--- In Homebrew_PCBs@yahoogroups.com, edrupp <edrupp@v...> wrote:
> I have a couple of photos of my milled PC boards at my robot clubs
web
> site. I should post more some day. I've been milling PCBs for
years and
> have gotten good results
>
> http://frontrangerobotics.org/UltraSonic/
>
>
> - Edward Rupp
>
>
>
> Brian Chapman wrote:
> >>Can you give me a rough idea of what sort of considerations are
> >
> > involved in the machine to work at that kind of scale? I don't
think
> > I've ever seen a mill that small and my drill bits only go to
#80.
> > :-) I guess spindle runout is a major factor there? <
> >
> > Roy, sure, trying to stump me right off the bat, eh? <g
> >
> > I purchased a Sherline tabletop mill and lathe and later
converted
> > them to CNC using a "turnkey" system from FlashCut.
(www.sherline.com)
> >
> > The Sherline machines, roughly, each are the size of a sewing
machine
> > and are driven with an IBM 600e laptop I purchased used.
> >
> > I bought Sherline because, when shopping, all the various
reviews I
> > read were glowing about the quality of the machines. Perhaps as
> > importantly, I bought Sherline's "ultimate" package that
included,
> > among other things, quality accessories such as Jacobs chucks
and also
> > quality collets. Quality accessories, as I understand it, have
much to
> > do with a machine's cutting accuracy.
> >
> > I use collets only with miniature cutting tools; I've read that
> > collets provide greater accuracy than chucks.
> >
> > I'm a member of the yahoo SherlineCNC list
> > (http://groups.yahoo.com/group/SherlineCNC/?yguid=225428826), and
> > spindle runout is seldom mentioned there as a problem. More
likely,
> > threads will deal with problems such as Z axis backlash
compensation
> > and the limitations of leadscrews vs. ballscrews. A number of
smart
> > and talented Sherline owners have documented, and posted at the
site,
> > machine upgrades that they've developed.
> >
> > But, I don't think spindle runout is a problem. Let me give you
an
> > example. I have milled a negative mold of the side of a 40-foot
long
> > highway trailer in 1:87 scale (about 5-3/8" x 1-3/16"). Within
this
> > space are about 40 horizontal corrugations (grooves) that I cut,
iirc,
> > with a .012" ball mill.
> >
> > In between each corrugation (a space also .012" wide), in
vertical
> > strips, are rivets drilled with a .005" end mill (about 36
vertical
> > rows, or more than 1400 rivets). Each rivet is precisely placed;
none
> > "slide" into the corrugations. To me, this is the kind of
accuracy I
> > require -- and get -- from this tabeltop unit.
> >
> > BTW, I've drilled hundreds of holes on this or that workpiece
with #97
> > (.0059") drill bits and have yet to bust. Any sort of runout
problem
> > would probably snap these, but I'm guessing only.
> >
> > Let me ask you a couple of questions, Roy. What are the narrowest
> > traces that you would need to mill on a PCB surface (am I
thinking of
> > a copper-clad PCB ready for etching)? In between traces, what
are the
> > narrowest clear areas required; that is, what is the minimum
> > separation required between traces?
> >
> > Did I answer your questions?
> >
> > -Brian
> >
> > Brian Chapman
> > Evansdale, Iowa
> >
> > PS - I'm hoping, once Curt comes back from the holiday, he can
advise
> > me whether or not I can easily adapt the CNC Sherline mill for
use as
> > part of the EDM system I'm intending to assemble.
> >
> > The EDM plans I have include a logic board for driving the EDM
head,
> > but I wonder if I can't build the power side of the EDM system
only
> > and use the mill and CNC software for the rest. . . . I'm way
over my
> > head at the moment, but I hope to break the surface and tread
water
> > while I look around and figure out what to do next. <g
> >
> >
> > ---
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
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and Photos:
> > http://groups.yahoo.com/group/Homebrew_PCBs
> >
> > If Files or Photos are running short of space, post them here:
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> >
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> >
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