On Tue, 21 Mar 2017 00:58:18 -0400, Bob Engelhardt
wrote:

On 3/21/2017 12:11 AM, DoN. Nichols wrote:
My lookup shows 4.4mm (usually metric sizes for roll taps for
imperial screws. That works out to 0.1732", while the #16 is 0.1770" so
the thread will be a bit poorly formed.

Good Luck,
DoN.


Ummm ... these are Balax taps and this Balax page shows that a .177
drill will give a 70% thread.
http://balax.com/products/thredfloers/12288-000

I'm not used to thinking about threads in percentage terms, but 70%
sounds pretty good to me.
70% will be plenty strong enough. If tapping punched holes in fairly
thin material you can get away with a slightly undersized hole because
the metal will just extrude away from the material surfaces. Remember
that a high pressure cutting fluid is good to use because the thread
is being formed.
Eric