Homebrew PCBs

--- 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