drilling holes in PCb's

[Simon]

Well I've made my first board in my new house  but I think I'm having problems drilling the holes in it, how do you guys centre and drill your holes ? I use a dremel on a stand but really I can see some are not centred and I can't figure out how to do better as I'm doing it by eye.

Any tips ?

[Zad]

Yep, Dremel on a stand. Have you etched centre holes in the pads to help the drill locate? You can always tap a small recess in the pad with a punch or similar spike if you need to stop the drill skating about. What sort of drill bit are you using?

[mikeselectricstuff]

You MUST have holes in the pads in your artwork to act as centre-marks.
If you forget, use a sharp pointy thing to make centre marks.,
These holes should be smaller than the actual drill size to avoid a gap between the hole and the pad due to over-etching , which makes soldering harder. 20 mil (0.02") is a good  size for all drill diameters.
Drills should be carbide, as fibreglass eats HSS drills.
Make sure  your drilling area is well lit so you can clearly see where the drill is going. Dust extraction or blowing helps a lot. 

[Curtisbeef]

Get a peice of plexiglass and drill a hole in it, then line it up with the PCB hole you want to drill and use it as a guide.

[Simon]

Get a peice of plexiglass and drill a hole in it, then line it up with the PCB hole you want to drill and use it as a guide.

That's a good idea, yea I have all 0.51mm holes now so that they act as a close centre hole and to ensure I don't end up with any pad area without copper

[joelby]

At home, I use the Dremel and Dremel drill press stand, but my university has one that drills from below. You line the top of the board up with a guide and a built-in magnifying glass, and use a foot pedal to activate the drill. Much quicker and more accurate than using the drill press.

[djsb]

You mean one of these variodrills

http://www.megauk.com/pcb_drilling_machines.php

Had one in my last job, very good, but a bit expensive for home use.

David.

[mikeselectricstuff]

Even with a standard Dremel, a foot-operated on/off switch is useful.

[JohnS_AZ]

I've always found it best to hold the PCB is a small vise while drilling. The mass of the vise holds everything still while the drill bit takes it's first bite. Mine looks a lot like this one (although I spent a lot more) ...

http://www.harborfreight.com/4-inch-jaw-capacity-drill-press-vise-30999.html

[lhc]

Proxxon drill with drilling stand and foot-operated switch. Way better than Dremel.

[joelby]

You mean one of these variodrills

Yep, that's the one!

[Zero999]

I don't see the problem.

I tend to use large drills and can get away with up to 1mm for DIL pins.

Look at a typical piece of varoboard and compare the hole size to the pins.

[Simon]

well I just found 0.7 is the min size all round and is far easier to centre than the 0.5 bit

[mikeselectricstuff]

I don't see the problem.

I tend to use large drills and can get away with up to 1mm for DIL pins.

Look at a typical piece of varoboard and compare the hole size to the pins.

1mm makes neat soldering harder, especially if the pad size isn't very big. You'll never get a track between decent sized DIL pads with 1mm holes. 0.7 to 0.8 is optimal.

[Zero999]

1mm makes neat soldering harder, especially if the pad size isn't very big. You'll never get a track between decent sized DIL pads with 1mm holes. 0.7 to 0.8 is optimal.

That's it, I make the pads as large as possible and avoid tracking between DIL pads like the plague because it can cause problems with bridging unless a solder resist is used.

If I do need to track between pins, I'll make the pads smaller and use a smaller drill if needs be but it's not very often I'm forced to do it.

[wd5gnr]

Another thing to do is get a piece of perf board with the same spacing you need (almost always .1"). Drill one hole. Line up the perf board with the PCB and clamp it or otherwise secure it. Now you can count holes and drill. If you have small enough bits that won't be perfect, but it helps.

Another way to go is a cross slide vise or an indexing vise (one axis only). These aren't too expensive although they are probably bigger than the Dremel!

[Simon]

hey that's a good idea, some sort of vise, maybe home built that lets you slide it on the two axis's but still that's a lot of calculations to be hand done