Homebrew PCBs

Thanks Tom , that makes it more clear. If its not too much 
effort, I would like to see a few basic pics of the machine you 
own. With Nawide machine having belt drive, what RPM did this run 
at ? I'm curious, what do you think is a "good" RPM for manual 
drilling  around the 0.6mm - 1.5mm diameter range ?

I know your talking 100k RPM and above for the very large and 
expensive Excellon CNC production drill machines.

Was it quick to change drill bits on these machines ? My guessing 
is the spindle would feed far upwards so the collet pops up 
through the flat panel giving you access to it.

Adam

twb8899 wrote:
> Adam,
> 
> The Excellon Uni-Drill uses a dc motor and lead screw to move the 
> spindle up and down. There is a series of adjustable limit switches 
> to set the travel distance. The air operated clamping "foot" is 
> between the optical scope and table surface and clamps the board 
> before drilling to prevent movement that would break drill bits.
> 
> When the foot switch is depressed the pressure foot clamps the board, 
> spindle travels upward, drills through the panel, drill retracts and 
> the clamp releases. You can watch the drill bit come through the 
> board in the screen. 
> 
> The Nawide and Aetna machines use an air/hydraulic spindle feed with 
> the feed rate controlled by a needle valve. The Nawide machine is 
> very quiet because it has a dc motor and belt driven spindle. Any of 
> these machines can also be operated with a stylus and drill template.
> The optical scope is used to make a master template and then the 
> stylus is used to "trace" the template pattern and drill the board. 
> An experienced operator can drill 80 holes per minute in a stack of 
> three boards in the stylus mode. If I'm drilling a single lot 
> prototype I just use the scope at about 20 holes per minute.
> 
> If there is any interest I will post some photographs of these 
> machines which would answer most of your questions. You would be 
> impressed with the accuracy of these machines not to mention the ease 
> of use and reduction of operator fatigue.
> 
> Tom
> 
> 
> --- In Homebrew_PCBs@yahoogroups.com, Adam Seychell 
> <adam_seychell@y...> wrote:
> 
>>
>>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
> 
> 
> 
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