Tapping a Square Hole (Square to Your Material That Is!)

I have always been vexed by having to tap threads in a hole so that the threads are square to the top of the material I was tapping. I found a nice solution using a block with a groove in the side.

Start by putting the tap in the hole. Notice the tap I am using has a somewhat flat profile on it’s side.

Next, place the “jig” in place to align the tap. This jig is an old hydraulic valve with the right sized groove in the side of it. Start tapping the hole, while keeping the tap pressed against the inside edge of the groove.

After you have the threads established, you can slide the jig out the side to run the tap down further.