Homebrew PCBs

Isn't a desire of my own, from pcb laminates datasheets you can read 
recommended drill bit speeds.
It is about 100.000rpm for an 0.25mm to 10.000rpm for 4mm. To drill a 
0.5mm drill hole on FR4 is recommended 60.000rpm with infeed of 37mm/s. 
But this is just to give a longer live to the drill bits. Lower rpm just 
need lower infeed ( i guess).
On westwind http://www.westwind-airbearings.com/pcb/index.html you can 
see 80.000 to 210.000rpm spindles (in a price range like cars i guess), 
they have air bearings, water cool and need a lot of equipment to 
operate. Also the cheapest (but still expensive pcb cnc's) use cheaper 
spindles like 
http://www.centerline-inc.com/partners/kavo/kavo_product_documents.php 
of 60.000rpm.

You are right when say i should look at tool cost more than just speed. 
Making a speedy machine but with big run-out will result in damage tools 
anyway. And more than a carbide bit price, is a good bearing, which 
should also live longer.

My only wish is to run between 30.000rpm and 40.000rpm all tool bits 
bellow 1mm. But never bellow 30.000rpm for these. And i hope to make a 
machine capable of this.

Simao

lcdpublishing wrote:
 >
 > I can understand and appreciate your desire for speed, however, there
 > are many drawbacks to this speed as well. Heat is going to be a
 > problem - keeping the bearings from getting too hot will be a problem.
 > Making sure that the spindle and tool all run perfectly true - within
 > 1 to 2 microns at worst is key. Any run-out at the tool will
 > eventually cause the bit to wobble and that leads to breakage. Power
 > is generally not an issue with these small drill bits, but if you are
 > overdriving, you have to account for that in your power requirements.
 >
 > I have probably drilled a couple thousand holes in PCB stock using a
 > large woodworking drill press. I believe the speed I am running at is
 > around 2500 RPM. The most common size drill I have been using is .75
 > MM (.030") and I go up or down from there for various components.
 > >From what I have observed over time, the drills don't break or dull
 > due to slow spindle speed, they break due to operator error -
 >
 > feeding too fast
 > not having the bit aligned on center of where to drill
 > moving the part sideways while drilling or retracting
 >
 > Speed helps, but attention to method will save more bits in the long
 > run.
 >
 > Chris
 >