How to Correctly Hand-Tap a Hole
Taps Are Brittle – Handle With Care
For taps and dies to cut, they have to be harder than the materials they are cutting. That makes them brittle, meaning, they can be easily broken.. something you want to avoid at all costs.
Lubricate!
Lubricating the cutting threads can reduce friction binding and help with chip removal. You don’t need a lot, a little goes a long way.
Take Your Time
You really don’t want to mess up a tapping job. Breaking a tap off in a hole —especially below the surface level will cause you untold frustration and possibly a rambling of crude expletives!
Remember, taps are crazy hard, so trying to drill one is not only difficult, it's guaranteed to ruin your part and your day. Take your time, go slow, this is truly one of those situations where haste makes waste —of several hours of your time and your wallet.
Break Up The Chips
Once the first full teeth begin cutting, the metal is removed is a long chips. The flutes provides clearance so the chips can be kept clear of the cutting teeth and pushed out the top of the hole.
It is extremely important that these chips be broken up to avoid jamming and breaking the tap. Turn the tap in the cutting direction until you start to feel it bind. At this point, turn the tap slowly in reverse until you hear, or feel a ‘click’ of the chip breaking away from the material being cut. The vast majority of tap breakage can be avoided by making sure you break the chips, and the smaller the tap, the more important it is, so stop every revolution or two.
Yes, this process is extremely labor intensive, and good luck if you more then one hole to tap. You are gambling all of the time you already put into that part, on each and every hole that you tap.. hoping and praying that your tap doesn't snap...
OR YOU COULD JUST STEP UP AND GET A TAPPING ARM ALREADY.
The A-32 starts at only $2900, can tap up to 9/16" with a tolerance of .0020". It takes SECONDS to tap a perfect hole, no broken taps, no hand lubricating, no breaking chips, no digging broken taps out of parts, no scrapped parts... It will literally pay for itself in one job.
