Drilling a PCB

[robmdall]

Searching around here I have found some great tips on drilling component holes in PCB's. Drill press, 'quality bits', center punching each hole, etc

One aspect that I am suspect on is if you should place the PC board on top of a piece of scrap wood or other substrate while drilling. I have seen the occasional photo of a PCB being supported by a drill vise with nothing underneath, completely supported by the vise.

Is there a preferred way? Is there a method that allows for better control over the drilling process, better bit life, etc

Thanks in advance for any thoughts.

Rob

[John Lyons]

I have never used anything under the board.
The drill press I use has a metal table with a large
hole in the center.
Use the fastest speed you can and the sharpest bits.
(carbide for a drill press...try drill bit city online.
The board is so thin and the speed so fast that there really
is no need to back up the hole(s) to be drilled.

[Joe]

This is what I do:
-When drawing the layout, make sure there is a small hole etched in the middle of each pad. This eliminates the center-punching, as the etched hole serves the same purpose of centering the bit.
-Tape the PCB to a 2x4 scrap, and drill the holes with a normal hand-drill, holding the board sideways. It's a lot faster than using a drill press.

[soggybag]

I have a Dremel Drill press, which works well. Though I'm not sure that it's the best for the job. It was cheap, $30 or $40. So if you have a Dremel tool this might work for you. If you can get one of those PCB drill bits they work better than the standard type drill bit.

Definitely etch the center of the hole at each pad this is probably the best piece of advice. The drill will center on the hole since goes through the fiberglass easier than the copper, where the bit tends to skate.

[T1bbles]

I use double sided sticky foam (used for making '3D' greetings cards) and fix the board to an old door panel, I then get a printout of the PCB and stick that to the top of the board also using double sided sticky foam (pushing the bit into the foam acts as a good guide for centering the hole) Then I sit on the floor with the panel, pull out the dremel and drill the holes by hand with a teeny tiny bit, not sure how big the bit is, I just made sure it pushed snugly through a perfboard hole.

After all the holes are done I peel off the foam from underneath, and the foam from on top. Then I have all the right holes drilled in all the right places.

Bear in mind I do this BEFORE etching as I draw on my layouts with a pen, so it's like playing join-the-dots.

That's my method anyways, works for me

[tiges_ tendres]

I was in a pinch and bought the smallest bit I could get at a hardware store (Black Oxide).

My usual technique is to make sure that my bits dont drill into anything but the pcb in order to prolonge the life of the bit, however, when I tried this method with the hardware store bit, the backside of the hole was chipped and busted up.  Putting a scrap piece of wood behind the board helped a little with this issue, but the real solution was to use a bit designed especially for the purpose.

I get mine from Jameco.  The shank of the bit is larger so that accurate placing in the chuck is easier.

[G. Hoffman]

It's a lot faster than using a drill press.

No, its not.  Sorry, but it is not as fast, and it is not as good a job.  Its impossible to keep a hand drill as square as a drill press, and you are always going to take longer to line up the bit with the holes.  That's just the physics of it.  You're moving something heavy into a precise position, vs. on a drill press where you are moving a small light piece into a precise position.  You may be more used to doing it by hand, so it may be faster for you right now, but if you got used to a drill press you would be much faster than you are now.

I've tried it both ways, and I like backing up the board (the exit holes are a bit cleaner), but there are some problems with it.  You need to move the backing boards along with the circuit board or the bit can be pulled sideways, which will reduce the life of high speed steel bits, and can shatter carbide bits.  (I'm not saying it always will, but if you do it too much it eventually will.)  I like the idea of clamping or screwing the board (presumably through the mounting holes) to your backing board.  That would make it much easier to remember to move the backing with the board.


Gabriel

[Skruffyhound]

No, its not.

I beg to differ. Maybe. If we are talking about a hand drill like a battery powered Makita/Dewalt/Bosch etc, then I can see the point, I think that might be slower, but if we are talking about hand drilling with a Dremel/clone then it's got to be faster than a drill press.
I drill all my boards looking through a magnifying glass, by hand and it is fast. I've never broken a bit and I've never messed up a pad.
Having said that, you are right that they are not as straight as a drill press would be, they all have a (very very) slight lean to one side, but since I maintain the same position to the board all the way through, they are uniform. On double sided boards this angle would be a potential problem (slight as it is), on single sided it's irrelevant, and the tedium of drilling can be over in half the time .
I could use the drill press standing next to me all day but I prefer not to.
Horses for courses, I just prefer to take the pain quickly since I etch a limited number of boards, if I needed to do this one day a week I would use a press, or maybe just shoot myself

[Ibanezfoo]

I don't put anything behind my boards when drilling.  I have a cheap Harbor Freight drill press that has an iron plate with a hole in the middle.  I don't know what kind of steel the drill bits are, I've been lugging these thing around for years and so far they haven't dulled from all the boards I've drilled.  They drill fast and clean, no tearout.  I drill after I etch and the bits just kind of center themselves inside the pads.

[R.G.]

And now for the eccentric old guy's method~! 

Take a Dremel drill press invert it under a plywood surface. Screw it to the bottom of the plywood so it can drill UPWARDS through the hole in the plywood you have so thoughtfully put there before beginning. Adjust so the dremel forces the drill bit just a bit (actually, 0.075" or so) above the surface of the plywood.

Arrange the plywood on some kind of stand so it can become a mini worktable for drilling.

Arrange a small USB camera so it rests immediately above the hole the drill bit comes up through. Affix it there so it doesn't slide out of position.

Put an undrilled PCB on the plywood, and adjust camera/dremel/etc to get a close up and in-focus view of the surface of the PCB on your computer screen in real time. Remove the PCB. Extend the drill bit to be fully through the thickess of the PCB, and stretch two threads over your video screen with masking tape on each side to make crosshairs *exactly* where the drill bit point comes out.

When this is all in place and checked... well, you have lept to the end already. Place the PCB, then slide a pad under the crosshairs. Hold the PCB firm and stroke the Dremel. If you have done your work well, a hole appears right under the crosshairs as the bit drills through the board from the bottom. Repeat as needed.

How much magnification you get depends on your camera. A USB microscope will give you an up-close and personal view.

Happy holes!

[Skruffyhound]

 

[puretube]

And now for the eccentric old guy's method~! 

Take a Dremel drill press invert it under a plywood surface. Screw it to the bottom of the plywood so it can drill UPWARDS through the hole in the plywood you have so thoughtfully put there before beginning. Adjust so the dremel forces the drill bit just a bit (actually, 0.075" or so) above the surface of the plywood.

Arrange the plywood on some kind of stand so it can become a mini worktable for drilling.

Arrange a small USB camera so it rests immediately above the hole the drill bit comes up through. Affix it there so it doesn't slide out of position.

Put an undrilled PCB on the plywood, and adjust camera/dremel/etc to get a close up and in-focus view of the surface of the PCB on your computer screen in real time. Remove the PCB. Extend the drill bit to be fully through the thickess of the PCB, and stretch two threads over your video screen with masking tape on each side to make crosshairs *exactly* where the drill bit point comes out.

When this is all in place and checked... well, you have lept to the end already. Place the PCB, then slide a pad under the crosshairs. Hold the PCB firm and stroke the Dremel. If you have done your work well, a hole appears right under the crosshairs as the bit drills through the board from the bottom. Repeat as needed.

How much magnification you get depends on your camera. A USB microscope will give you an up-close and personal view.

Happy holes!

Around the year 1971 we used a similar construction @ the Siemens R&D field-lab...
some .5mm bits lasted for up to 2 holes,
others for> 4000...
(vastly depending on the amount of nicotine&coffee the young dude had used before...  )

[G. Hoffman]

No, its not.

...but if we are talking about hand drilling with a Dremel/clone then it's got to be faster than a drill press.
I drill all my boards looking through a magnifying glass, by hand and it is fast.

Let me start by granting that I'm extremely spoiled for available tools - I grew up in a shop most people would covet as their dream shop and when I go into most tools stores I don't see anything I don't already have - and that may color my view, but I can't understand the appeal of cheap tools and not using the right tool for the job.  Also, I tend to measure most things to the nearest thousandth of an inch.

As for the Dremel; all that does is insure your holes are oversized and oval.  Don't get me started on the "bearings" they use in Dremel "tools", but one thing you will never achieve with a Dremel is accuracy.  The amount of run-out in their spindles is huge (ever seen a slow speed close up of a bit in a Dremel?  It isn't pretty).  There are only two things I use a Dremel for, and neither of them require accuracy - one because I am just using the Dremel to remove the larger portion of the material before I clean it up with a chisel and gouge, and the other because I will be filling in around inlays with charcoal dust that will invisibly eliminate all of the slop left by the Dremel.  While the bearings in a cheap drill press may not be much more expensive, they are larger, which makes it much easier to machine them with an acceptable amount of run-out.  

We used to use Dremels to rout saddle slots for acoustic guitars (still an unfortunately common practice in some shops), and getting a good straight slot was a nightmare.  The day we switched to a laminate trimmer was a moment of revelation around here.  All of a sudden, you didn't have to fiddle with things - they were just right.  You could take deeper cuts in each pass without the bit going all over the place, you didn't have to struggle constantly to make things right, and the job was done in less than half the time (a big deal when you run a repair shop, because time really is money).  

Plus, Dremels still have the problem of trying to move and accurately position the heavy thing with awkward balance instead of the light thing, which is always slower than moving the light thing while the heavy thing remains stationary.  The only way I can see that being faster is if you are not marking your holes with a center punch, but in that case the accuracy is going to be even worse.  

I can't begin to tell you how much I hate Dremel "tools".  Second rate tools for doing second rate work.  The only thing they have going for them is that they are cheap, but the only thing they are really good at is filling a dumpster!  Oh, you can figure out work-arounds to achieve decent results, but it will always take longer than it would using the right tool, and in my life, my time is far more valuable than the cost of buying good tools.


Gabriel

[R.G.]

Around the year 1971 we used a similar construction @ the Siemens R&D field-lab...

The bottom-drill was a staple of the PCB industry - in industrial strength versions, of course, which the Dremel-and-USB cam are clearly NOT.

It's an old, old solution, but one which is cobble-able by the DIYer now with a camera replacing the optics. My earlier version of this, which I posted on usenet before there was a WWW, used a cheap rifle scope, with internal crosshairs, modified for the purpose to focus to 2".

[R.G.]

Let me start by granting that I'm extremely spoiled for available tools - I grew up in a shop most people would covet as their dream shop and when I go into most tools stores I don't see anything I don't already have - and that may color my view, but I can't understand the appeal of cheap tools and not using the right tool for the job.  Also, I tend to measure most things to the nearest thousandth of an inch.

You're correct - that just means that you have luxuries that most techies can't even imagine.

As for the Dremel; all that does is insure your holes are oversized and oval.  Don't get me started on the "bearings" they use in Dremel "tools", but one thing you will never achieve with a Dremel is accuracy.  The amount of run-out in their spindles is huge (ever seen a slow speed close up of a bit in a Dremel?  It isn't pretty).  There are only two things I use a Dremel for, and neither of them require accuracy - one because I am just using the Dremel to remove the larger portion of the material before I clean it up with a chisel and gouge, and the other because I will be filling in around inlays with charcoal dust that will invisibly eliminate all of the slop left by the Dremel.  While the bearings in a cheap drill press may not be much more expensive, they are larger, which makes it much easier to machine them with an acceptable amount of run-out.

But "accuracy" is relative. Relative to a hand-held electric drill, which it the next most common competitor, the Dremel is a wonder of accuracy.

I do prefer drill presses, but didn't get acceptable runout until I got a jeweler's drill press. Expensive, but good for the job. I quit breaking bits.

I can't begin to tell you how much I hate Dremel "tools".  Second rate tools for doing second rate work.  The only thing they have going for them is that they are cheap, but the only thing they are really good at is filling a dumpster!  Oh, you can figure out work-arounds to achieve decent results, but it will always take longer than it would using the right tool, and in my life, my time is far more valuable than the cost of buying good tools.

I think that you may be missing that the average DIYer is, in fact, trying to achieve 1960s accuracy with 1800AD tools, for under $100 for whole tool inventory.

Shoot **I** wish I had the tools you hint at and I've been a tool collector/buyer for my entire adult life.  I encourage you to take the challenge I've been wrestling with for a few decades now - how can I enable others without the tech background or training to become self sufficient enough to make fun musical toys? If you can help think of ways to let them achieve good results from the side-effects and throwaway leavings of today's technologically rich society to do their hobby, you will be doing them a huge service.

[G. Hoffman]

Shoot **I** wish I had the tools you hint at and I've been a tool collector/buyer for my entire adult life.  I encourage you to take the challenge I've been wrestling with for a few decades now - how can I enable others without the tech background or training to become self sufficient enough to make fun musical toys? If you can help think of ways to let them achieve good results from the side-effects and throwaway leavings of today's technologically rich society to do their hobby, you will be doing them a huge service.

Your probably right.  I'm just a tool junkie, and just like a heroin junkie doesn't like cheap dope, I don't like cheap tools.  Dremels just don't do anything very well, and a cheap drill press is so much better and not much more expensive.  I also can't let go of the idea that time is money, so a cheap slow tool costs me more than an expensive fast tool.

As for my tool collection, well, it is one of the benefits of being in a 40 year old family business.  Believe me, I do understand how lucky I am in that regard.


Gabriel

[mth5044]

A question along the lines of drilling a PCB -

Is there any powder/shrapnel that needs to be considered when drilling a PCB? I don't mean big pieces flying around like when I drill enclosures, I mean dust from the PCB. I live in a one room apartment, and I'd really like to do up my own PCB's, but I'm a bit worried about drilling at my desk, which is a only a few feet away from my bed, some more feet away from my kitchen, etc.

[G. Hoffman]

A question along the lines of drilling a PCB -

Is there any powder/shrapnel that needs to be considered when drilling a PCB? I don't mean big pieces flying around like when I drill enclosures, I mean dust from the PCB. I live in a one room apartment, and I'd really like to do up my own PCB's, but I'm a bit worried about drilling at my desk, which is a only a few feet away from my bed, some more feet away from my kitchen, etc.

There is dust, and if you can set up a little dust collector/vacuum near where you are drilling, it would be a good idea, but it's probably not super critical if you are only doing a few occasionally.  If you were doing a lot, you might have to worry more.


Gabriel

[robmdall]

Thanks for all of the responses. RG you're killing me  I added your suggestion to my to do list.

So what I gather is that the best for me would be:

1) Design PC B's with hole in center of pads.
2) Use the best drill bits I can afford.
3) Drill press  using fast speed (Bench or Dremel). I have access to both.
4) Drill PCB with no substrate under it. (I do worry about the effect on the component side of the board).

On a side note: I too get all horny regarding purchasing new tools, however, I believe, like most here I suffer from FD (Financial dysfunction). This is an illness that keeps my tool corral kind of slim.

I also believe in the true DIY spirit, make use of what you have and do the best you can do.

Again, thanks for the great responses.

Rob

[G. Hoffman]

4) Drill PCB with no substrate under it. (I do worry about the effect on the component side of the board).

You'll get a bit of blow out on the top layer of the board (or bottom, I guess), depending on how sharp your bit is.  It shouldn't ever be enough to cause problems.


Gabriel