Homebrew PCBs

I have built a pivoting type drill press , but haven't done anything 
about improving the visibility of the drill location. I admit , that 
having a magnified image would make it a lot easier get accurate holes. 
Another big improvement would be to have a foot switch that operated a 
solenoid to feed the drill. That way both your hands hands can hold and 
position the PCB. Both these features are not so straight forward to 
implement. The mechanism of the pivot is superb, smooth and virtually 
zero side to side play.
I think the best approach is like the commercial units. Have the drill 
under the table. Mine is above the table, but will convert it sometime 
down the track. The advantage of having the drill come up from the 
bottom is you have a flat table top to work on, with no drill motor in 
the way. Of course this means you now must have a means to view the hole 
location from above.

A method once talked about on this group was to use a cheapy CCD camera 
module and a TV with a composite video input as the viewing device. 
Cross hairs are drawn on the CRT screen.
If you can get hold of cheap TV and CCD camera than I'd think this is 
the best way to go.

The idea you have of projecting an image to a translucent screen might 
be more effort, but I haven't seen the results so I can't comment if its 
worth going down this route. Not to spend too much money, try one of 
those 12V 20W halogen roof lights that are fashionable these days. The 
screen could be tracing paper behind some 3 mm plexigalss. In my opinion 
the major amount of work would be fabricating the framing to mounting 
everything, since the optics must be stable and also adjustable.
How about a section of  50mm diameter PVC drain pipe with the lenses and 
screen mounted at each end. Some frame made out of MDF to could be used 
to position this pipe. what is the distance between the screen and lenses?
If there is no distance between them than just cut the appropriate size 
hole in some MDF to mount them both in this hole. Adjacent to this hole 
you cut another to mount the halogen lamp.

Adam.







Stefan Trethan wrote:
> 
> i got out my box of lenses and built a "optical bench".
> Ok, ok, it is only a board, a white shoebox as screen, and a flashlight,  
> but... better than guesswork.
> 
> 
> The results seem very promising. i could reach the required magnification  
> in a semi-dark room easily with the flashlight brightness through a piece  
> of paper.
> 
> Best seem to be lenses with very short focal lengths (~~~5cm).
> I also tried using a mirror to deflect the projection, and it too worked  
> surprisingly well.
> 
> I'm still unsure whether i should make the projection screen above or  
> below the drilling table. above the table requires big cutouts, but below  
> would need a semi-transparent projection screen. I guess paper would  
> work...
> 
> 
> One BAD, BAD thing is because of the lens, if you move the board right the  
> image moves left, and vice versa. same for up/down. But i don't want to  
> make a more complicated setup with multiple lenses and mirrors and  
> whatnot. I think one will get used to the reversed movement.
> 
> The whole thing will be made from MDF or plywood, not sure if i should try  
> to seal the dust out or just keep everything open so i can easily remove  
> the dust.. also, the lens should be mounted in a way that allows to adjust  
> it, not sure what i will do there..
> 
> 
> Well, i'll let you know what i come up with.
> 
> ST
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