Handy Hole Size Checker

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Introduction: Handy Hole Size Checker

About: I am an automation engineer but I will give anything a go. I don't know if you call if pessimism or just being an engineer, but I look for problems everywhere, then I look for some weird, left field way to s...

We've all been there, we grab a screw or bolt that we need to fit, but wait! What size is it?

Normally I'm pretty good with sizing bolts by eye but screws are a different matter.

Seeing as you are going to end up at the drill bit box anyway, why not make it work for you.

Enter the hole checker...

Step 1: You Will Need:

Obviously, you need a drill bit box.

It is important to use a PVC type for several reasons:

  • They take far more punishment when in my van (metal ones dent then don't close)
  • Thet tend not to be as noisy as the metal ones
  • When you drill them (if the drill is fast enough) the hole is very close in tolerance to the drill bit, perfect for this intructable

You need ALL of the drill bits from the box

Finally, you need a drill

Step 2: Drill Pilot Holes

My set runs from 1mm to 13mm in 0.5mm steps (25 bits in all).

I drilled pilot holes with the 1mm bit.

I made a mistake here as I drilled the pilot holes for the bigger bits too close together and the holes would have met, you will see this in the next set.

Try to have the holes in a logical order.

Step 3: Drill and Mark Up

Once all of the pilot holes are drilled, take each drillbit in turn and drill out.

Keep the drill speed high and drill in a single pass (don't ebb in and out or the hole will be oversized).

When all the holes are drilled, mark them with a permanent marker.

The last image shows a machine screw being tested.

For a clearance fit, the bolt or screw should slide in easy, the test screw was M6 so 6.5mm was a nice clearance.

If you want an interference fit the screw should have to be threaded into the hole.

There you have it, an easy but time saving workshop hack.

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    5 Comments

    Now the only problem is telling metric from imperial drill sizes apart. And don't forget about letter sizes! Oh, how do I hate America's unit system...

    4 replies

    This link will I use a lot in the future! Thanks.

    Oh besides: the holes in the drillbox are handy too!