Drill Small, Precise Holes.




Introduction: Drill Small, Precise Holes.

About: Creative swashbuckler. Writer for MAKE Magazine, presenter of inventions on TV, radio, magazines and newspapers. Professional problem solver. Annoyingly curious. Hacker of all things from computers to clot...

This Instructable well help you drill a line or grid of holes with 1/400th of an inch (0.06mm) tolerances. Or so. The holes in this photo are 1/32" (0.8mm) across and 3/64" (1.2mm) apart, but the same technique can be used to drill even smaller or closer holes. And you can go bigger too, the same method will use to drill a grid of holes of just about any size.

It's not super difficult, but it does take the right equipment, attention to detail, and practice. I probably drilled 30-40 holes before I got the technique down well enough to get even spacing most of the time.

It's worth noting that this works best on soft material like plastic and wood. Harder materials like steel are a bit tricky since I don't center punch the holes which can cause the drill bit will to wander a bit.

Thanks to my brother Nick for giving me the nudge in the right direction to figure this one out.

Step 1: Tools

Here's what you need:

  • Small drill press. The one shown is an adapter for a Dremel rotary tool (Dremel #212), plus a small keyless drill chuck for the same. (You can possibly use a full sized drill press, but I'm not sure you'll get as much accuracy, and getting a #71 bit to fit in a full sized drill chuck is a pain.
  • Small drill bit. Or several of them, since they're so easy to break. If you're drilling soft materials don't spend a lot of money on them. This is the cheapo set I used.*
  • Right angle jig. If you don't have one I'll explain how to make a quickie out of old scrap wood (like this one) in step 2.
  • Business cards or notecards. Anything is fine as long as they're uniform thickness. This is what we will use to determine the space between the holes.
  • Rubber bands I use a number of them to hold stuff in place. If you have some small clamps or vice grips or whatnot, those would be useful as well.
  • Safety glasses (not pictured because they were on my face when I took the photo).
  • Practice Material. Scrap wood or plastic or whatever so you can practice before going at your final project. Trust me, you won't want to drill your final project the first time out. You'll probably also want something disposable to put under your material as you drill through it.

It's also helpful to have a dust brush, dustbuster, and/or vacuum cleaner around. While you're working keeping the workspace clean is vitally important because any small bit of sawdust or debris can throw off the accuracy.

* Often drill bits smaller than 1/16" are called "wire gauge" bits. This term can be helpful when shopping for them online.

Step 2: The Jig

You can skip this step if you already have a right angle jig. If not, read on...

We need something to hold our drilling target and our spacers securely in two directions. It's not hard to build with some scrap wood and a couple of bolts. You could even use an old picture frame.

To build a quick and dirty jig:
  • Scrap wood
  • Wood glue
  • 2 carriage bolts, washers and wing nuts. Get the appropriate size to fit though the holes of your drill press base. In my case 3/8" by 2" long.

  • Saw
  • Miter box, or protractor or some other way of determining 45o.
  • Drill.
  • Clamps.

First give the scrap wood a light sanding if there are any uneven sports. Then mark an angle at 45 degrees across the face of your scrap wood and cut the wood in two along the mark. A miter box or miter saw can help you cut it accurately.

Second flip one of the pieces over and put them together. This should make a 90o angle. If it does, glue and clamp them securely. If not, try again.

Finally after the glue is dry, drill appropriately sized holes through the jig so the bolts will be able to fasten it securely to the drill press table. (3/8" holes in my case.)

Got all that? Good, lets go!

Step 3: Prepare the Drill Press

First make sure everything is clean. Yes, that's far from easy in most workshops, but at least make sure there's no dust, sawdust, grit or other stray particles around the immediate vicinity. Getting a piece of sawdust in the works is really all it takes to throw off the alignment.

This goes for the drill chuck too. I needed to blow a bunch of air through it to get it clean. The first time I tried to use it there was a bit of grit inside that kept the drill bit from centering correctly.

Attach the jig. This should be pretty self explanatory. Make sure it's secure.

Check the Stability of the drill. Or Dremel in this case. Give it a little push left and right, backward and forward. Ideally it shouldn't wiggle or move at all. But it probably will. You might have adjustment screws that can be turned to reduce the wiggle somewhat, so try that first. In my case I still had a about 1/2mm of wiggle remaining, so I secured it by wrapping a rubber band around the body and putting both ends around the top of the depth stop. This got rid of the small wiggle, and since both the drill and the depth stop move at the same time it doesn't get in the way of any of the mechanics of the drill press.

Insert the drill bit. With very very fine drill bits it can be a bit tricky to get them perfectly centered. First close the chuck all the way. This makes sure the gripping jaws are centered and clear of debris. Open the bit very slowly while trying to insert the bit. When the bit slips in stop, adjust the location of the bit so the shaft is deeply in the chuck but the bit groves are all visible, and tighten. This will help clamp the bit securely and directly in the center rather than off to one side.

To make sure it's centered, put on your safety glasses and give the bit a good look while while turning the drill on. The bit should appear exactly the same width when spinning as still. If it looks wider at the bottom or really blurry in general it's off center, which will give you inaccurate holes and will break bits. (See illustration below.) Take it out and start over.

Step 4: Drill the First Hole

1) Adjust the location of your fence and drill for the first hole. All subsequent holes will be closer to the fence (see illustration) so plan accordingly.

2) Fasten the drilling material securely. If you are drilling through the material be sure to have something under it that's safe to drill into. I couldn't figure out how to get any of my clamps where I needed them for this project, so I used a bunch more rubber bands to both keep the box securely against the jig, but also to keep it from lifting during drilling.

3) Once you've got everything ready, drill your first hole.

Easy! Next comes the tricky part...

Step 5: Drilling a Line or Grid

This is where we really get down to business and find out if all of our careful planning and dust avoidance has payed off. Speaking of dust avoidance...

1) Remove any dust or drill shavings from the area.

2) Figure out how many cards you need to space your holes (center to center). For my example 3 of my business cards gives me 3/64" (1.2mm) distance.

3) Count out that many cards and put them between the jig and the drilling subject.

4) Drill your next hole.

5) Clean up your drill shavings.

6) Repeat steps 3,4 and 5 by adding layers of cards and drilling until you have as many in your row as you need. Be sure not to miscount the cards. (I did this more than once during practice and it will throw off your spacing and can cause spontaneous face palm.)

If you're just doing a line, then you're done!

If you want a grid, you need to make another line, offset from the first. Repeat the steps above, but also put cards at right angles to the first set. This will offset your material in two directions.

For advanced users you can draw a pattern using different numbers of cards and drill bit sizes. Like this amazing project, only smaller.

To do this at a larger scale size everything up and use sheets of plywood or square doweling as spacers. It makes the whole thing easier since you don't have to worry about sawdust or your drill press moving fractions of a millimeter.

Anything unclear? Ask in the comments and I'll try to help.



    • Fix It! Contest

      Fix It! Contest
    • Water Contest

      Water Contest
    • Creative Misuse Contest

      Creative Misuse Contest

    74 Discussions

    I am enormously gratified that you young uns are learning simple machine shop practices from each other. Some of us did nine year apprenticeships and are forever grateful to our teachers and the opportunities we were afforded by good public education.

    Depending on the drilled medium and the hole size, to debut them, consider any of these: dental floss, thread, or guitar string (steel). Of course, one would need to be careful not to change the size or shape of the holes in the process of demurring.

    1 reply

    Provided the back side of the hole (side needing deburring) is accessible. Taking a drill bit that is sizably larger than the holes just drilled, center the larger drill bit over the hole lightly debur the hole using the cutting point. Granted this process takes more time, but the results are difficult to compete with when done properly.


    2 years ago

    You could also make a simple system using threaded rod, that could be adjusted using the turn of a screw.

    It's similar to done CNC machines. Cool, idea. :)

    One example that comes to mind is printed circuit boards. One of the reasons I use surface mount parts is because I hate to drill holes in pcbs. It's difficult to drill the holes in line for something like a DIP IC. This is a nice approach.

    OTOH, if you don't make your own pcbs then the point is somewhat mute.

    I use to drill PCBs and to be honest I never had a hard time doing it without a jig (but using a dremel on a vertical press). Anyway I found your instructable useful to make holes for a speaker, for instance.
    nice one, thanks.

    to the OP, v nice, simple jigs make life easy ;) I often spend as much time setting up jigs as doing the work, measure twice, cut once! Well shared!

    to Pedrol46 and AttilaTheHun re PCBs

    Tungsten PCB bits usually have a larger diameter shaft than the tip and so are easy to centre in the chuck, no flute to get in the way. They cost more but are well worth it!

    If you clamp the board lightly with your hand, the board will centre to the drill as the bit is SLOWLY lowered into the copper, since it has a hole in the copper to align to. Once centred, hold tight. You can drill many holes in PCBs very quickly like this by feel as much as sight and get very accurate results without a jig!

    Oh, and a nice way to ensure that the centre of a drill lines up if you don't have centre bits. Place putty etc on the tip of the drill and apply a pin. Adjust until the tip does not wobble (rotating slowly) This is the center line of your chuck.... align work to the pin, clamp & drill.

    Good quality quill/bearings, lots of light and firm clamping make for accurate work. And jigs rule!

    Nice post and great idea. If you metric folks (yes, a lot of us in the US know you are superior) want something more useful than 382 um business cards then try 3M brand post-it notes (yellow sticky notes). They average 100 um and are remarkably uniform throughout the pad. It's been awhile since I was using them a lot but I think it was less than 5 um variation between sheets. I used to know the inventor and he told me that precise control of the manufacturing process was a key piece of the secret sauce.

    I know this is a necropost but nice job! I will put this to use.

    One rotary tool problem possibly needing to be addressed is the wobble of the bearing in the plastic housing molded into each side of the case. You can get quite a bit of play at the end of the bit causing breakage and inaccurate placement. Frank Ford posted instructions on how to use a small band of heat shrink tubing around the outside of the bearing, creating a tight fit when the case is screwed back together. Don't overtighten the screws when you put the case back together or you will strip the threads.



    2 years ago

    Wow that's super helpful! Thanks!

    Perfect timing, I was wondering how I was going to drill four holes in a coin to turn it into a button. This is a lot easier than having to rotate the coins exactly 90 degrees three times.

    Very good idea! I might use a round head woodscrew instead of card on one side. Measure the pitch of the thread and screw or unscrew one complete turn if the distance you require is one pitch. Fraction it if you want anything different.

    Put two screws in one face and one in the other. This keeps the three-point location rule.

    The gap the screw-heads create will also take care of any swarf or shavings that slip down the sides.

    Card is probably simpler though!

    1 reply

    aw shucks, I was going to recommend this approach smiles.

    As opposed to screws could use depth micrometers coupled with gauge blocks for gross distances and get within.001 accuracy consistently without a learning curve

    To drill precise holes, always at least start the hole using a "center drill", also called a "combined drill & countersink". It will cut into the material exactly where it is placed. If you don't have the exact size (they can be bought from 0.010" to 3/4" diameter) just use one close to what you need but only barely cut into the material leaving a dimple that will position your normal drill bit to finish the hole without wandering. It takes a few minutes longer but the results, if you need accuracy, will be worth it.


    2 years ago

    This is one of the best pieces of advice I have EVER seen regarding drilling a series of holes in a straight line - AND THEN TO TOP IT OFF, You've done it on a tiny scale with rather good precision! AMAZING! :D

    What is your experience drilling hard stuff like steel? any success with this technique on that?

    1 reply

    For something like steel you could glue a small piece of plastic on top. The drill would get started in the plastic and be stabilized when it reaches the steel.