--- In
Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
> On Wed, 24 Mar 2004 15:01:19 -0000, mr_gees100_peas <geovar13@h...>
> wrote:
>
> >
> > Hi I've ben reading this group for a while and I feel
confident
> > enough to make my firt PCB. I decided to use the PnP transfer
paper
> > and iron it on. Right now I manage to transfer my design to a
copper
> > bard fairly well. The thing is that I see all those holes and they
> > are so smal. I hear some people drill the holes after they etch
> > becase they can use the hole as a guide. Well, I tried driling a
few
> > holes in a practice pice of copper board nd I keep missing the
mark.
> > The board an't een etch yet but I wondering if I should drill the
> > holes fist that way I can add more resist in case I screw up.
> >
>
>
> I know that a hand-fed drill will always center very easily in the
hole.
> it is really just aiming close to it and drill.
> If you have problems try to use no drill press, hold a small
drilling
> spindle
> in your hand and drill manually.
> Of course you can't use carbide drills. get HSS and grind them
every now
> and then.
> (easy enough to grind).
>
> The aiming is slightly harder with a drill press because the drill
can not
> really move,
> you have to be spot on with aiming or let the board move.
> It all depends on the quality of equipment you use. a good drill
press
> with no runout
> and a very sharp bit drills very easy, so it is very easy to drill
the
> edge of the hole.
> A rather dull HSS bit in a bad wobbly spindle will center itself
much
> better.
>
> If you need no high-quality hole walls it is really fast to work
with a
> handheld drill.
> you will not break HSS bits.
>
>
> I do not like the "add more copper when i screw up" approach.
>
> Also make BIG pads! the standard pads are for throughhole plating.
>
> ST
Good accessment.
Before the CNC machine, I would etch the center of the pads as well.
That left a place for the drill to start and offered holes that were
aligned much better.
Also, it is worth getting a machined pin socket in 300 and 600 for
using as a template for drilling.
Drill out the unit with brand new, sharp drills.
Align and drill pad #1 of your IC, the pad 14, or 28 or whatever the
opposite corner would be.
If you don't have a mark, use a pin or pointed tool to get a mark in
the dead center of the pad. This will help keep the drill directly
on center.
Place a loose drill in hole #1 right thru the chip socket. ditto for
the other pin. Tape may help, or if you are on a board they may stay
by themselves.
I took old, dull drills and cut them short to make offer more
clearance.
Now you can drill the remaining holes much better. Even with a hand
drill.
Dave