Making a home brew printed circuit board

[chucketn]

I have finally succeeded in making a pcb for my Rotary Table indexer project. Next step is drilling the through holes for the components. The component leads range from .020” to .042” Can I use HHS drill bits or should I get carbide?
I have a HF bench model drill press and an X2 mill. Which would be better? What speeds for the dill bits? Any other suggestions/cautions?

Chuck

[refinery mike]

i drilled out many a PC board with regular hobby store HS steel drill bits. They wear down but they aren't expensive to replace. I am sure that carbide is the way to go if you do it for a living. When i was a kid i drilled many a hole for circuit boards with a drill bit ground from a needle from my mothers sewing kit, and an egg beater drill ta boot. Carbide bits brake like super easy so you need a solid drill press or mill to use them. I see them at flee markets on occasion.

[chucketn]

Thanks for the response, Mike. Any idea how many holes you can get from a reasonably sharp HSS bit? I have about 130 holes in 1 board at the moment, maybe 1 more if it goes well.

Chuck

[SteveHGraham]

I bought carbide. Better holes. As you drill over and over, your bit will get thinner, and the holes will get smaller. If you drill enough holes, it will cause a problem.

[hammermill]

the other thing the carbides give you is small holes dead on. the tiny part is only a small part if the total drill.
most tool places have them in sets of 20 to 100 and decimal sizes for one it really matters.
here is a example


http://www.goldmine-elec-products.com/p ... ber=G15725

another advantage the home hobbiest usually doesnt need it the carbide gives a truer hole that plates best when doing thru hole plating.

[Harold_V]

What speeds for the dill bits?

If you make the decision to use carbide, it's highly unlikely you'll have enough speed to be too fast. Run the fastest you have, as small drills will normally tolerated speeds in excess of 10,000 rpm. For an example, a 1/16" drill driven @ 6,000 rpm is cutting @ 98 fpm.

The speed recommendation would most likely apply to HSS drills, too, although unless you keep a steady feed rate, you risk wearing the drill prematurely. Letting it dwell in the cut will cause rapid decline of the drill.

Carbide, for drilling fiber glass, is generally a better choice, as it limits destruction on the back side, where dull HSS will break the surface of the board.

Harold

[Lew Hartswick]

No one has mentioned the PCB material. If its something like G10 then the carbide is certainly desirable
but not mandatory. If youre using phenolic base material common steel bits will be just great.
...lew...

[chucketn]

Lew, the pcb material is from Radio Shack. The package does not state what type it is, but made in China... It appears to be brown in color looking at the edges. I have not etched it yet.

When it warms up a bit, I will take it out to the shop, cut it to size and put it in the ferric cloride to etch.

Chuck

[Lew Hartswick]

If it's brown it's phenolic. The G10 stuff is green and you can see "cloth" texture in it. That is the
fiber glass that makes it a beast to drill. (Note! "Fiberglass" is /or use to be/ a trademark)
...lew...

[CraigS]

Carbide bits are the way to go but they are very brittle, if you look at them wrong they snap. You need a good high speed drill press with minimal run out. Even then just a little movement holding down the board and the carbide bit it toast. My recommendation is to use a hand held tool and HSS bits. Keep a small pocket stone or some silicon carbide paper available to resharpen every once in a while.

I have done thousands of PCB holes with a little Pitman motor mounted to a pin chuck salvaged from a broken flex shaft. The little motor about (1.25” dia x 2” long) is rated for 12V but I run it up at 35V using a foot switch to turn it on and off. The foot switch shorts the motor when you take you foot off the button causing the motor to stop in less than a second. It helps if the motor is stopped when you move the bit to a new hole so the bit doesn’t wander and bugger up your traces. This setup can only be used with HSS bits, I tried carbide once, they snapped within the first few holes.

One of the RC aircraft or boat electric "inrunner" motors would work great.

Craig

[oldvan]

Harbor Freight offers a hard to beat 20 Piece Solid Carbide Micro Bit Grab Bag for $6.99.

As others have stated, trying to use them in anything handheld is a quick way to get
rid of them. A Dremel-type tool in their press might work OK.


I've had excellent results using carbide bits in my CNC router; it uses a Bosch Colt for its
spindle which I upgraded it to a precision 1/8" collet from Precision Bits. I hate
waiting for the board to etch, so use Isolation Routing and let my router cut the
traces for me.