Thread: Tapping holes

Originally Posted by ClintO

I have to tap a couple of dozen 3/16"UN and M4 holes in 1.6 and 2mm mild steel sheet.
In the past I have done it by hand for smaller numbers of holes but I really hate using tap holders and have trouble keeping them square to the steel.

Is it feasible to do the tapping with a cordless drill? If it is I would appreciate some hints.

Clint

Can't help you with cordless drill.

But for only a couple of dozern holes whats wrong with a hand tap? If the taps tapered it helps. Easier to start than bottom end. Tends to find centre by itself even if you start off a little crooked.

In any case what I found makes a big difference is a industrial type lubricant. Just a drop of that and the taps cut through like going through butter. Can get the stuff from bolt suppliers etc. But you probably already know that.

I have used a cordless drill in the past to tap small holes in steel and it is easier to keep it plumb but because you can't "feel" the tap cutting it is very easy to break the tap.

I do agree with tripper about making sure you have tapered taps to start, It makes the job a lot easier.

Rowan

Hi,
I would not use the cordless drill.Taps (and dies) operate by cutting grooves in your metal. The waste material must be broken off before it jams itself under the thread cutting teeth and could snap the tap, so to speak.

How would you keep the cordless drill square,if you can't keep the tap wrench square ?

Try putting your tap into a drill press and drop of the motor drive belt.

This will keep your tap holes square. Pull the chuck around by hand and keep firm downward pressure until the tap bites. Reverse half a turn every full turn or there abouts to break off the waste.

Do use tap lubricant. Yes it will be slow but you won't break a tap.
If you have only 1.6 and 2 mm to play with you will have bugger all thread engagement.

An alternative might be using Cleco nuts which are like pop rivet type nuts which attach to the sheet. I think a set of Cleco pliers would come in under a $100.

Cheers
Grahame

G'day All.

When tapping holes in thin sheet. I drill a hole smaller than needed and then dent the hole down by hitting a centre punch into the hole and then drilling the right size hole.
This gives more metal for the tap to bite into.

Hooroo.
Regards, Trevor
Grafton

For the size you are tapping you WILL more than likely break the tap. The process requires a clockwise anti clockwise back and forth motion to cut and clear the cut. A trick to keep it all square is to set the tap in your drill press mount your job on the bench and WITHOUT turning on the drill use your hands to turn the tape as you would with the tap handle.

Another option (If you are going to be doing a lot of tapping) is to purchase a spiral or gun tap.

Spiral and gun taps do not need to be backed off. They are used in production manufacturing.

Greetings
Use the right size tapping hole and usage of Treflex then using a battery drill for tapping is a breeze.

I wish you well
_Richard

A battery drill works great for small taps in thin material. I do it all the time.

Just don't press the trigger at the same time as turning the brain off

Take it easy, feel the pressure you're putting on the tap and back up half a turn when needed.
That's what the variable speed and reverse switch are for. (aren't they??)

You're more likely to have a problem with the keyless chuck not gripping well enough on cheap battery drills than anything else.

"Tap Magic" is the lubricant to use, it's brilliant. Just one drop on the tap before each hole.

Greolt

cordless drills work fine for tapping holes in thin material like you are doing just drill the tapping drill 0.1mm larger and use a gun tap, these are machine taps which will push the swarf through the hole rather than using a hand tap which will just clog up with chips.