Cutting a hole in a PC Board?


I have an odd question I hope some of the more experienced members can help with. I am building a prop. The base of the prop is this board :

To accommodate the attachment of a small panel-type meter (part of the prop), I need to cut a round hole in the board. The hole is about the size of a quarter. My question is, is it possible and how to cut the hole safely? The rest of the components on the board will be dummies. The meter is controlled by an Arduino mounted behind the board.

Many thanks :roll_eyes:

First you need to determine if that board is fiberglass, such as FR4 used in standard pcbs, or if it's some other kind of material, like phenolic [usually a lot cheaper]. If it's fiberglass, you will want to take extra precautions in cutting or drilling it, to keep the dust cloud down, and out of your lungs especially.

other than the dust, yes its possible, the trick with it is anything you use will want to grab onto those already drilled holes and tear out. I have used crude methods such as a really fast drill, a hole saw and basically no pressure

If the hole is 1/2" or less, just use drill bit.

If it’s bigger than that, you can drill a starter hole and use a jigsaw to cutout the hole… then a half-round file to smoothen it, then sandpaper the edges deburr it.

Just DO NOT gather the PCB dust, line them up, and snort them like cocaine. Nope… use the real thing.


Is it possible to just cut it with a utility knife if one goes over and over on the same spot? Will it eventually go through?


A utility knife?

I'd bet you'd cut your finger first in an accident before your blade goes through the PCB.

Probably true, bad idea. :blush:

you can use a knife to score, break, and cuss about the horrible quality edge you got, cause on most boards a sharp knife hardly makes a scratch

These come in various sizes:

Besides what I said in my original post, I actually do drill FR4 pcb material on occasion, but I use a hand drill, and actually pack it top and bottom with "wet" tissue or clothe to catch the dust. Of course, this won't work for a hole almost 1" in diameter. That large a hole is a problem.

You're never gonna do this sort of thing well with a utility knife, without, as mentioned, having a high probability of cutting your finger off, or slitting an artery. I would try to think up another way to mount what needs to be mounted.

Edit: I just had a different idea. The hole punches elsewhere mentioned are amazingly expensive, but possibly a nibbling tool might work. You start with a smallish hole that could be drilled with a hand drill, and nibble it to size. Looks like it will do up to 1/16" thick material,

GreenLees are expensive (and overkill) I think.

BUT I FOUND THE SOLUTION… (without using a jig-saw/file)

I sometimes use a step drill bit to bore large holes in aluminum. But haven’t tried it in PCB material.
So quickly went to the shop and tried it on scrap PCB…

It’s like cutting butter! No problem at all, no chipping, smooth edges (just a little sanding to make it baby-butt smoother).

Buy something like this.

Of course, your largest hole will be limited by the biggest diameter in your step drill bit. (1" to 1-3/8", depending on what you buy).

But first, you need to drill a 1/2" pilot/starter hole, so the step drill bit can actually go through.

Photo of my quick test.

yea, that did pretty good. I keep saying I need to get a step bit, now theres a new reason

I expect you'd need to either grind the whole, or drill it using an extremely high bit speed to prevent it from grabbing. Since you probably don't have a means of turning a bit that size fast enough, I'd use a Dremel grinder and either a stone or cutting tool about the right size. You can easily file the hole out with a round file once it's started, but if you have a Dremel available that would be a far easier way to do it - a cutting wheel will go through fiberglass as though it was butter. The dust isn't [u]especially[/u] dangerous, but I'd suggest either do it outside and keep yourself upwind of the dust, or use a face mask and damp the workpiece to keep the dust down.

Trust me on this... Use a hand reamer. Start with a pilot hole drilled at reasonable speed. Watch the dust.

Then finish it by hand with a hand reamer. They look like this:

There is NO other way to get a good, clean hole in my experience. I have 4 different sizes, and have been using them for years and years without sharpening even when doing lots of sheet aluminum holes (1/8"!!)

There is NO other way to get a good, clean hole in my experience.

Check out my photo above using the step drill. It's like pressing down a knife into butter.

Hand reamer, cool idea. Can you get them in quarter size - about 25 mm?

Get a step-drill/Unibit & cordless screwdriver/drill, will do a nice job without grabbing & ripping. Large diameters available. Home Depot carries them.