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.