DIYbanter - View Single Post - How can I automatically tap 500 holes in 5/16-18 thread size using ahand drill or drill press?

Trevor Jones

wrote:

Trevor, thanks for the cordless drill advice but Been there and done
that and $50 bucks down the drain

Well. Dunno what to suggest then.

Work up a set of callusses, maybe. :-)

At least, drill bigger pilot holes. Try to run about 60 percent of the
diameter of the tap for the pilot. Most tap drill charts are at about 75
percent, and if you are drilling any smaller hole than 75 percent thread
engagement, then slap yourself for making life harder than it has to be.
The loss in strength is disproprtionately small, compared to the ease in
tapping that you gain.

I've done a pile of holes, mostly 1/4 inch coarse and fine, and a
right pile of 10-32 ones with a cordless drill.

Done a pile with a reversing Sioux Air drill too, that was even faster.

You twitchy when holding stuff that's supposed to be steady? If so,
work out a way to support yourself for steadiness.

If the volume makes it worthwhile to spend the money, take a look
online for tapping arms. Just ar eversing air motor, with an arm that
keeps it pointed in the right direction. Pretty expensive, but usefull.

Gunpoint taps shoot the chip ahead of the tip, and are used for
tapping through a hole. If you have the clearance behind the hole, use a
starting tap and run it down in one shot, fairly fast. Use a lube. The
Tapmatic Al. stuff works well, as does beeswax, or the cutting lube sticks.

Have fun!

Cheers
Trevor Jones