Introduction: Tapping a Straight Hole With the Aid of a Drill Press

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About: I am the co-director, co-founder and lead instructor for the Customs for Urban Teens Program (CUT Program). Started in 2009 we take at risk youth and teach them how to build custom cars. I am a journeyman mach…
This is a description of a simple operation that might make tapping holes a little easier! Ever wondered why your taps have a little chamfered hole in the top? Read on and learn

Step 1:

tools and supplies:
material that needs a tapped hole
drill press
center punch
hammer
center drill
tap drill ( sized to tap )
chamfer
live or dead center
tap
tap handle or wrench
tapping fluid
safety glasses

Step 2: Center Punch Hole Location and Center Drill

Using your center punch and hammer locate where the hole is to be tapped. Centet drill hole location ( sorry forgot pic ) I cannot stress enough the importance of a centet drill when hole location has to be accurate!!

Step 3: Drill Hole With Appropriate Drill Size

Now drill your hole with the drill you selected. There are charts available for this. There is also a formula for this as well.

Step 4: Chamfer Your Hole

Using your chamfer tool, chamfer the hole. I like to go slightly larger than the major diamter of the thread to be tapped. This gives a nicer lead into the thread with no burrs. It also looks better.....

Step 5: Line Up Tap

So at this point install your live/dead center in drill press. Install tap handle on tap. Line up your taper tap with drilled hole. Now the tricky part. Bring your live/dead center down on the little hole in the top of the tap. Now you should be lined up dead cenrer on your hole.

Step 6: Start to Tap

Ok now apply some cutting fluid. Apply pressure to drill press and rotate tap handle. If you dont have a tap handle any wrench will work with this method. For every rotation of 360°of cutting action rotate tap reverse 1/4 turn to break off chips. If this is not done broken taps may be in your future!!!
If you are tapping a blind hole start with a taper tap and once full thread engagement is achieved switch over to a bottoming tap.

Step 7: Finish Up.

Once you are finished tapping the hole clean out all the chips and cutting fluid. If done correctly you should have a nice straight tapped hole.
I use this method quite frequently when I have to tap very large holes. If everything is locked done to bench tapping a 3/4" npt hole is pretty easy.
Hope this helps make life a little easier
Enjoy