Homebrew PCBs

I was so impressed with your Laptop Drill that I made a tabletop 
version. (I told ya I liked it!)
Elegant simplicity...


I put a 12" X 15" base and table on mine; complete with non-skuff 
feet.
There's a photo in the photo section.

There's a simple stopper block attached under the 12" arm.
It has a small slot cut in the bottom of the stopper with a dowel 
rod connecting to the Lifter/Lower arm. 
A simple cam made from a plastic toy wheel was glued to the dowel. I 
sanded it flat on one side to provide cam action for gravity feed 
and lift clearance. (About 1/4")
The slot in the bottom of the stopper allows you to completely lift 
the arm to change bits.
The retainer for the Dremel is an old scrap of Chimney-Mount antenna 
strap, connected to a 1/4" tension screw using an angle bracket and 
square nut.
I cut a V-Slot in the end of the arm using a hand held jig-saw. Not 
very accurate on verticals so I used a sliver of cardboad to shim 
the Dremel true vertical.
I added 1/8" holes at the back to organize my small carbide bits.

The whole project took only a day.
Cost was $0.00 not counting the Dremel or bits. Made from all scrap 
stuff on hand.
Other scrap used includes a 2x4 and 1x2 boards, a small piece of 
plywood, (2) 1/4" x 3 1/2" bolts w/ wingnuts, finish nails, 4 screws 
(in back uprights), and glue.

It works great on my single boards, and the arc that the Dremel 
travels is not a problem. It's too slight.

Thanks again for the great idea + photo, jankok !

Byron



--- In Homebrew_PCBs@yahoogroups.com, "jankok5" <kok@s...> wrote:
> I uploaded a picture of my laptop drill press to the photos 
section.
> 
> Mr. Moderator, maybe you can move that picture, and the following
> text, to the files section.  (I couldn't upload to the files 
section.)
> 
> The drill press shown in LaptopDrillPress.JPG was built for 
drilling
> small PC boards.  Total cost was less than $100 and it was built in
> an afternoon.
> 
> I thought a lot about how to aim the drill accurately.  I tried
> mounting a rifle scope to the front of a Delta drill press with a 
10
> inch throat.  That didn't work very well because there wasn't much
> magnification obtained from the scope, and because it was hard to
> judge the position front-to-back where the drill would land.
> 
> My conclusion was that the cheapest/best aiming solution was just 
to
> be able to get my face up close to the axis of the drill bit and be
> able to easily move my head around to view from different angles.
> So I built the device shown in the picture.
> 
> The black platform is cut out from a 5-inch floppy disk carrying
> case.  The main reason for using that was that it provided a 
plastic
> hinge that bends in one axis without any play/slop/unwanted 
movement
> in other axes.  The platform can twist (become non-planar) a little
> bit, but that doesn't cause enough of a problem to bother fixing.
> If necessary, the platform could be stiffened by glueing a board
> underneath it.
> 
> The drill motor is a battery operated Craftsman.  The gray plastic
> band that holds the drill onto the wooden arm is a conduit mounting
> strap, a molded plastic part used to attach electrical conduits to
> walls or ceilings.  A drill press with a hole saw was used to drill
> out a semi-cylindrical cavity on the end of the wooden bar, to hold
> the drill motor.
> 
> To use the drill press, I put it in my lap, hold and position the
> PCB on the platform with my thumbs, and pull up on the platform to
> drill a hole.  The accuracy is quite adequate for drilling pads for
> integrated circuits.  I use a #60 high speed steel drill bit.  I
> haven't tried a carbide drill bit.
> 
> How much error is caused by having the platform tilt instead of 
move
> linearly along the drill axis?  Say the drill is 5 inches from the
> hinge in the platform, and say the platform is raised about 1/8 
inch
> to drill a hole.  Then the platform rotates 1/40 radian.  For small
> angles, 1 - cos a ~= a^2 / 2.  So the error (elongation of the 
hole)
> due to tilting is about 5 * (1/40)^2 / 2 = 1/640 inch, about 2 
mils.
> Since I adjust the drill "by eye" so that it is perpendicular to 
the
> platform, the error caused by misadjustment is probably similar or
> greater.
> 
> Cheers,
> - Jan Kok