Homebrew PCBs

twb8899 wrote:
> Adam,
> 
> I like your drilling machine. If you flipped it over and put an 
> optical scope and air clamping foot on it you would have almost the 
> same machine John is referring to. There were several manufacturers 
> of these machines with the most popular one made by Excellon. It was 
> a Uni-Drill model 1230. The actually came with a stylus assembly for 
> template drilling and the optical scope was optional but almost 
> everyone bought the scope. 
> 
> They use a Precise #65 spindle with a variac speed control. You can 
> still find these machines if you look hard enough but many of them 
> went to the dump which is a shame. 

That would be a sore sight. Although I can understand many 
professionals simply have no use for a manual drill machine. I've 
heard the stories about the PCB business going through a rapid 
change in 1980's, even here in Australia. One business man told 
me the only places who survived were the ones who could get the 
new and automated processes working the quickest. This guy's 
business specializes in low volume, DS PTH, aimed at a lower cost 
solution for prototyping.  He knew of PCB fabricator that went 
under, simply because they had reliability problems in the new 
plated through hole line.

Unfortunately I haven't seen any of the drill machines here in 
Australia. I'd be very interested just looking how they are 
built. How was drill feed operated ? Was this foot pedal control 
or more elegant motor drive feed or hydraulics ? For quick 
experiment I attached a bike brake cable to the arm on my 
machine, hoping to operated the down feed by pulling the cable. 
It turns out there is far too much friction in the cable and you 
loose the "feel" and fine control of the drilling.

What is an "air clamping foot" ?

I'm imagining foot control would make drilling a lot easier 
because it gives you two hands to position the PCB for drilling.

Adam