Tools & techniques for drilling holes

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Tools

Engineers square

You’re going to need a square. Six-inch is fine, it’ll be needed to mark out your holes, and square up your table if you’re using a drill press.

Buy a quality square. You’ll use it a lot. This is a good unit.

Twist drills

Just buy your drill bits from your favourite retailer. These are cutting tools, so buy the best you can afford. If they go blunt or break quickly, buying cheap ones a second time makes them expensive.

I’ve ended up with sets of both metric and imperial sizes up to 12mm or ½”. Sizes above that, I purchases as needed.

Bosch drill bits

Here in Australia I will only buy Sutton. In other places, I would look for a reputable supplier like Bosch.

Holesaws

For the really large holes that don’t have to be super accurate, you can use holesaws. You can use them in a handheld drill, but a drill press makes is easier.

Holesaws can be bought most economically in sets, then can be expanded with additional sizes as required.

The arbors are generally common, so holesaws from other manufacturers will usually fit.

I use these Lenox-branded ones in Australia and it seems they are available on Amazon too. This kit has both the arbors you’ll need.

Step drills

I’ve only got one step drill, which is a Bosch metric item that’ll drill 4mm to 20mm holes.

Again, being a cutting tool, buy the best you can afford.

Ask your local hardware store or tool retailer for more advice if necessary, but many places only carry one manufacturer of step drill. Or maybe one “premium” brand and one “el-cheapo” import version.

This particular Irwin bit ranges from ¼” to 1-?” and would be what I would purchase if I needed another one.

Steel rules

Stainless steel rules, six-inch and 12-inch, are very useful. The ones pictured have both metric and imperial measurements, which is helpful.

I’ve picked them up for a dollar each in the stationary aisles in some of the variety stores. When you get them for a dollar, I buy five or six and just leave them around my shop, so I’ve got one handy all the time.

They’re not very expensive, and they’ll be accurate enough for the sort of work we’re doing on our motorcycles.

Scribe

Double-ended scribes are a few bucks each in the hardware store.

I generally use this style when I’m welding, and when they get damaged they’re only a few bucks so I’m not too worried about them.

Punches

A center punch is essential to locate the start of your hole and guide the bit in the right direction.

You’ll need one center punch, around 100mm long.

If you want to spring for a dot punch, this helps a little. It has a sharper point, which helps to pick up on the scribed lines compared to the flatter point on the center punch.

Of course you could buy another center punch and regrind it to a sharper point if its cheaper!

Engineer’s hammer

Get a hammer. You’ll need to strike the punches with it.

Suggest you go to the store for the hammer. I prefer a 24oz weight, but that’s pretty heavy. You might want a lighter hammer – 16oz is another common size. Pick one up and swing it around. Watch out for other people while you do this. And don’t upset the security people swinging a hammer around in the store.

Buy the one that feels more comfortable.

Deburring tools

A deburring tool or countersink will let you finish the hole off beautifully.

Noga countersink deburring tool

I use a Noga countersink similar to this one, but Noga are a premium brand – their tools are excellent – but the price is premium too.

Also, this style is only good up to the diameter of the countersink. For larger holes made with a holesaw, you need this style.

Engineers Black Book

Engineer's Black Book - Pat Rapp

Yes its expensive, but its really useful. Has the drilling speeds table plus tons of other stuff. I’m dumb enough to have bought two. One stays in my shop and one is in my office next to my computer.

Steps to drilling the ultimate hole

1. Mark the center location

This is critical. Use the scribe, rule and square to carefully layout the location of the center of the hole.

If you have a dot punch, find the intersection of your marked holes, and strike the punch lightly with the hammer. Check the location. If it’s good, strike the center punch in the same location and open up the punch mark to locate the start of the hole.

2. Assess the best method/tool for making the hole

I’ve put this step second, as the location of the hole might limit what tools you can use to make the hole.

  • Small holes (under 13mm), use twist drills
  • Large holes (above 20mm), use holesaws
  • Sheet metal (under 4mm), use a step drill

The spot between 13mm and 20mm is the hard part. Twist drills for sizes in this range are expensive. Smaller holesaws are available but the hole is very inaccurate.

You’ll need to weigh up the cost vs accuracy you need for your project.

3. Select a pilot drill size (if necessary)

If you’re starting a large hole, select a pilot drill big enough to accomodate the centre web of the main drill size.

4. Set your spindle speed (on a drill press)

If you’re using a handheld drill, you’ll need to calibrate your trigger finger 🙂

5. Secure the work

Secure the work in a vice or use clamps to hold it down.

Put it on a scrap of wood if you need to drill through and don’t want to damage the surface underneath.

6. Apply some lubricant

Use a cutting fluid or some oil (this isn’t critical, use engine oil if its all you have) to cool and lubricate the drill.

7. Put on safety glasses

Chips will go flying. Don’t be a dick. Protect your eyes.

8. Get into position

If using a handheld drill, position your body so you can keep the drill steady and straight.

When using a drill press, be sure you can reach the stop button in the event of a mishap.

9. Turn metal into chips!!

Start your chosen drilling machine and apply steady pressure.

If you use too much pressure with a small drill bit, you’ll snap it.

If you don’t use enough pressure, the drill bit will rub and not cut, just generating heat.

This is a “feel” thing and you need to do it to learn.

10. Remove the part and clean up any burrs on the hole.

Use a deburring tool or countersink. Press it against the hole and twist. It should cut off any burrs. Then it should start to cut a nice chamfer on the hole. Keep going until you get the desired chamfer depth. Totally up the you.

Matt McLeod

About the Author

I teach people how to build custom motorcycles by helping them build skills and confidence with my coaching, articles and training videos. I provide better technical information for custom motorcycle builders. And I shorten the learning curve getting you there.


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