Finding the Center of an Existing Drilled Hole

Why would you need to find the center of an already drilled hole? You ask. What would be the point of that?

Well, let’s say you’ve drilled a hole in a piece of wood. Next, assume your initial hole drilled was a ¾” diameter hole. Now, assume the hole-diameter should have been 1-1/2”, for whatever reason. And, let’s also assume that the 1-1/2” diameter hole needs to be centered on the ¾” diameter hole already drilled. A whole lot of assuming  going on here. That’s why you need to know how to find the center of an already drilled hole.

The ¾” dia. drilled hole is shown in the following Photo. This is just a scrap piece of wood. It’s a visual aid; I like visual aids.


Here is the Step-by-Step Process to Find the Center of an Already Drilled Hole
1) First, a drill press is req’d for this method.
2) Take your wood member with ¾” diameter hole drilled thru it, and insert the ¾” dia. drill bit into the ¾” drilled hole as shown in the following Photo.



Next, secure the wood member in place with clamps. The following Photo shows the wood member clamped down. Note the use of both clamps and drill press table fence to lock in place the hole position relative to the drill bit.



3) With the wood member ¾” dia. hole & ¾” dia. drill bit lined up as shown in the above Photo, ensure that there is adequate clearance to remove the ¾” drill bit (from your drill press) and install your 1-1/2” drill bit. The 1-1/2” drill bit centered on the previously drilled ¾” dia. hole is shown the following Photo.

4) Replace the ¾” dia. drill bit with a 1-1/2” dia. drill bit, and drill the 1-1/2” dia. hole. Problem solved. Photo of 1-1/2” dia. drilled hole & 1-1/2” dia. drill bit is shown in the following Photo.



Final Thoughts
The above is a short & simple technique (which I always love), and it sure can come in handy. Good to know.


If you enjoyed this post, I would be very grateful if you would share it by email with a friend, or on Google+, and/or Facebook. While I am being needy, would you give me a “Like” on my Facebook page (Woodworking with AJO)? My Facebook page “Like” button is on the right side of this page, or you can click on the link shown below for my Facebook page. Thanks a bunch.

Woodworking with AJO | Facebook

Until next time, Take care