Drilling out PCBs

[unknown_entity]

Where can i find some brill bits that are the right size for drilling out PCBs. The smallest I could find was 1/16in. I thought of using dremel bits but there all some type of tile cutter or goofy router thing. No regular drill bits.<p>The best I could find was some reconditioned bits from a surplus dealer.<p>This is the first time i actually tried to make my own PCB. I'm using the "dry transfer" traces and a double sided board from radioshack.
What would be easier, Drilling it out first then run the traces or the other way around?
Is there anything else that i should know that would make this any easier?

[haklesup]

Check out this link http://www.harborfreight.com/cpi/ctaf/D ... mber=34640 <p>50 piece set of just the right sizes for only $13 and they should fit in your dremel.<p>In case the link fails their item # is 34640-2VGA or search on "micro" I had trouble finding them searching on "drill bit". They also have a 20 piece set.<p>Got a set myself a while back. Hold the drill very straight, they are small and brittle and break easy.<p>As for drilling or laying out traces first I am not sure. seems like having the holes would help you align the top and bottom traces. Try laying out the desigh in a drawing program first then printing to scale and copying it onto the final board

[Chris Smith]

They are called "Number" Bits,... zero through sixty. <p>Any good hardware store carries them, or machinist supply.

[unknown_entity]

Well actually i've got a drill press so breaking bits shouldn't be a problem but it only goes up to 3100rpm.
What size "number bit" is used for standard lead size thru-hole compnents?
If I cant find someone who'll sell me just a few bits localy i'll end up buying those from harborfreight.
What I was going to do was just make a scale drawing, tape the drawing to the board then drill it out like that. Then I could put the traces on the board and etch it directly like that.
I've got a double sided board but i'll probably only use one side. So what would be better when drilling, copper side facing the bit or component side?<p> Thanks,
James<p>[ October 08, 2002: Message edited by: unknown_entity ]</p>

[Dean Huster]

The Harbor Freight deal is a good one, especially if they're sharp or resharpened bits. Carbide bits are the only way to go because glass epoxy board eats high speed steel for lunch and between meal snacks.<p>Hosfelt Electronics used to sell resharps. You'll find that most of these are about 1-1/4" long and have a 1/8" shank. Not just any drill press will handle them. I have a really nice machinists press, but there's just a little too much vibration with all that steel and it snaps the small bits. Instead, I use a Dremel Moto-Tool with their accessory drill press stand and the 1/8" collet -- don't use the cute little 3-jaw chuck because it's not true. Run the speed pretty fast, up around 10,000 rpm. Keep the mandril extension short, i.e., lower the head down within 1/8" of the pcb to reduce the slop.<p>I use one of those lighted magnifiers right in front of the work. Serves three purposes: light, magnification of the work and eye protection. And you must wear eye protection, because a carbide bit will break without fanfare.<p>I also have a boxer/muffin fan set up at the side of the work to blow the chaff away as I drill, keeping the marks in view.<p>Oh .. the reason for the edit: I forgot to mention to check the electronics surplus outfits for the carbide resharps. 1/16" is a BIG hole for pcb components!<p>Dean<p>[ October 08, 2002: Message edited by: Dean Huster ]<p>[ October 10, 2002: Message edited by: Dean Huster ]</p>

[L. Daniel Rosa]

I've done very few double sided boards. Disclaimer now given, I suggest laying out the top traces first and painting the bottom, then etching. Once side one is etched, use the dimples in the pads to start your drill bit, good alignment that way. Then strip the paint off the back, paint the top, lay your back artwork and etch again. You may find that laser printer transfer is less of a headache, even without the specialized films. I must admit though, that using rub-ons does allow one to work around imperfections.

[unknown_entity]

Right now I don't have a dremel. I've got a clarke metalworking drill press and it's less than a year old. If that doesn't work i could just use the college's equipment.<p>What really annoys me is that in the fabrication class i'm in they have done away with teaching how to etch your own board.
Oh by the way when I mentioned in one of my posts a while back I was going to college for an associates in applied electronics. I'm about 7 weeks into the first semester taking 13 credit hours. We just finished up flat-packs and tomorrow we start surface mount.

[MrAl]

Hello there,<p>In a pinch, i've used a pin.
Doesnt do as neat of a job, but it does
work in a dremel drill.
Also, ive ground down a 1/16 inch bit near
the end in a pinch also, so that it forms a
much smaller diameter bit.
Works untill you can find the right bits.<p>Also, i find that when using dry transfers it's
easier to drill after etching.
When using a hand pen, it's easier to drill the
holes first, then draw the pattern, then etch.
It also helps to use a 0.1 inch perf board
as a drilling guide if you are using dip
patterns and a pen.<p>Good luck with your circuits,
Al<p>[ October 09, 2002: Message edited by: MrAl ]</p>

[Dean Huster]

I agree with Al on when to drill the holes. I used to do all mine by hand before going to the toner transfer process.<p>With the hand process, the board was laid out on paper and this drawing was taped to the blank board. Then I used a punch ground down from a masonary nail to a really thin, sharp point to transfer the hole locations to the blank board. Then I drilled the holes.<p>The next step was to use Testor's #1103 flat red model paint to lay out the traces. I'd ring the holes first, then connect them together like a dot-to-dot puzzle using my paper layout as a guide. I used the bow type inking pens from an old set of drafting instruments for the paint. You could make thin, consistent lines with it as opposed to what an artist's brush could do. If it was a double-sided board, I let the first side dry and then added the donuts and traces to the second side. The pre-drilled holes made registration perfect, of course.<p>It's funny, but the #1103 flat red is the only Testor's model paint that would resist the ferric chloride etchant. The other colors wouldn't hold in the warm etchant and I don't know why. After etching, the paint comes off either by scraping or washing with lacquer thinner.<p>With the toner transfer process, I have four registration marks in the corners of the board. After transfering the first side to the board, I drill out those four marks and then turn the board over and apply the second transfer. That's where I found out that even the best LaserJets have linearity problems. Don't expect perfect registration over the entire length of the board.<p>Dean<p>[ October 12, 2002: Message edited by: Dean Huster ]</p>

[russlk]

My advice is to etch first then drill. Make sure your pads have a hole to act as a guide for the drill. Number 68 drill (.030 inches) will work for most leads, number 75 ( .020 inches) is the smallest I use, for IC leads.

[unknown_entity]

OK the board im doing is basicly 2 12v relays controlling a 120v a fan and xformer in sequence.
The terminals for the relay socket are not round like component leads the're more like a spade terminal so what would be better having a big pad and 2 smaller holes side by side so that the terminl will fit thru or a big pad and a single hole that will fit the terminal?

[russlk]

I would go with two smaller holes. Getting the solder to bridge all around a single hole might be difficult.