Homebrew PCBs

Hi Stefan,

The process of drilling metal under water I have done in the past - 
usually with very hard steels and at very slow spindle speeds.  

FOr PCBs, there could be a big problem though.  When drilling, the 
material may create a chip that is a "long string" which could fling 
the water all about your shop.  I have not drilled enough PCB 
material to know how the chips develope and break so I am unsure of 
this.

But, drilling under water is certainly okay to do.  It will keep 
both the tool cool and the material.  Carbide doesn't rust like 
ordinary steels, but the tool holders and such probably will rust.  
You could use a "Coolant" which is an additive you add to water to 
make "Coolant" used for metalworking.  This stuff contains rust 
inhibiors - you will find it at industrial suppply houses.  Be 
warned though of two aspects:

1) it may be difficult to dispose of depending on chemical make up - 
don't dump it in the yard or down the drain.

2) If left stagnent in a tank, bacteria may grow and it will smell 
terrible.  The synthetic coolants are less prone to this than the 
oil based coolants that are mixed with water.

Chris








--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
> Hi,
> 
> 
> whille looking around for a shop vac to catch drilling dust i had 
an idea.
> 
> If i set up the CNC for EDM anyway, why not simply drill the 
boards under  
> water?
> 
> Then the water could simply be discarded after drilling the hols 
and  
> milling the outline.
> 
> 
> What do you think? Any problems?
> Maybe the cooling from the water would even be good? Does carbide 
rust?
> 
> thanks
> 
> ST