Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
>
> As i said those are old pictures.
> 
> The stop screw is now right at the drill clamp, so that it comes
down on  
> the PCB. This holds the PCB down and it prevents the frame from beeing  
> tilted when reaching the stop and breaking the drill.
> 
> There is a counterweight clamped to the back of the frame, it is
balanced  
> so that it just thinks down, but around neutral seems good so you
have a  
> good feeling for the force.
> 
> Also, the bearing is not in the same hight as the drill tip, this
prevents  
> it going in a perfect tangent. I now put a wood block under the PCB
and  
> have angled the drill holder forward to make it straight again (this
angle  
> is adjustable with a screw). The two red plastic rods are no longer
used  
> to hold the drill, the front clamp is sufficient.
> 
> Added light and vacuum.
> 
> 
> If i had to do it again, i would use two plates, the upper one
triangular,  
> with a piano hinge at the back.
> 
> ST

Thanks, Stefan, for your comments.    I got my Proxxon drill and am
getting ready to build the drill press.

I am seriously considering the two-plate design, using two pieces of
half-inch thick (12.5mm) wood or plywood with a wood spacer and a
piano-hinge.    I would probably make it about 25 cm (10in) wide.  
Not sure how long of a lever arm to use--what do you think?    I
suppose that I will just let the drill bit eat into the lower board
when top plate is pressed down.   I suppose that I will place springs
between the two plates to hold the drill bit slightly elevated above
the workpiece when the operator lets go.   Then when the operator
applies downward pressure, the drill bit will be exactly vertical when
the drill bit contacts the upper surface of the workpiece.

I think this design would be even better than the one you built,
Stefan.  It would be lighter and occupy less space.    I might have to
attach an L-shaped pieces of wood to the upper wood plate to make sure
the drill bit is always held perpendicular to the upper wood plate.  
 I guess the longer the lever arm the better, so long as it isn't too
hard to store when not in use.    

Alan