PCB Hole Cutter...

[Promocom]

I have a circuit I want to put on several tiny (1/2") round circuit boards. I need a tool to punch or cut these circles out of a PCB board. I tried searching for a precision hole saw without the center bit but no luck. Has anyone seen anything like that or have any ideas?

Thanks,
Bill

 

[laroche73]

1/2" round pc boards

Bill, I took a look at the hole saws in my toolbox, and most of them have a small hex screw holding the base part of the hole saw to a standard drill bit. I think most of mine came from Sears. I'd loosen the hex screw and replace the drill bit with a broken off bit or an equivalent short shaft. The drill bit's only there to guide the hole saw anyway, so a drill press would serve the same function. There'll be some pcb waste from the hole saws' coarse teeth, you'd probably want to start with a 5/8" one (7/16" would be better, might be hard to find) to get a 1/2" I.D. on your pc boards. Finding a hole saw made with the thinner spring steel may work out better. - CAL

 

[jake_stone2000]

When I worked at a printed circuit company we used the "punch and die" method to cut the fiberglass board into circles, ie; those wristwatch boards with the microcontroller and the gold plated pads for contacts, we used to punch out the blanks after the "hole throughs" were drilled, and plated.

 

[Klaus]

I think a hole saw would be quite rough on the copper layer, you'd need one with very small teeth for such a tiny circle. You must also clamp the blank board very well to the drillpress table or you get a'very' bad finish.

How many is 'a few'? If that's less than 10 boards there is another method.
If you have access to a lathe that is. You need to clamp a 3/4" dowel into the chuck and face its end flat. Cut the boards square, a little over size and clamp them against the dowel end, one at a time, with a piece of waste ply wood and pressure from the tailstock's live centre. You can now carefully turn it round with a very good finish.

Cheaper than getting a special punch & die, which would require a punch press to use. Better finish than a hole saw - but you need a lathe :wink:
Good luck,
Klaus

 

[Promocom]

I want to make several hundred so the lathe trick would just be too much work. The punch & die though the best method is not cost effective for me. So a fine tooth hole cutter sounds about right but finding one is the problem. I did see something called an annular bit (hollow drill bit) that may work but seems to need a special drill press, I'm still looking into that. If anyone has used them please let me know.

Thanks all!

 

[Klaus]

That sounds like a good idea. I've seen hollow drill bits used to drill large, deep holes into concrete to fit expanding bolts into. It looked like a diamond grit tipped tube and it produced neat concrete cores.
They used water cooling, not sure if one can run a diamond tipped drill dry.
There are companies that do diamond tipping if you cannot get the right size ready made. It sure would outlast a hole saw for that many holes, fibregass PCB board base blunts tools very quickly unless they are carbide tipped.
Klaus