What size drill bit for a 1-72 tap?

[killgar]

I'm going to be drilling and tapping some holes in stainless steel. I will be using 1-72 screws and a 1-72 tap (obviously). What size drill bit should I use to drill the holes prior to tapping. Thanks.

 

[dr_fosg8]

#53 wire gauge drill.

 

[PT Doc]

This is a great chart to have

http://www.brokenbolt.com/images/starrett-inch-metric-tap-drill.pdf

 

[Nathan the Machinist]

Rigid tapping 1-72 in thee Olde Grey Pig gives me cold sweats. You can't even see it through the door, you have to open the door and blow things off to see if things survived.

...I hate tiny taps in stainless...

Moly Dee and OSG roll form taps save the day here.

 

[12345678910]

If at all possible, check your designs to see if you can go up a thread size


two and four are much easier to do than zero, and one and two

 

[killgar]

Thanks all.

I had a feeling that tapping stainless with such a small/fine tap might be tricky, and this thread has reinforced that feeling. I took 12345678910's advice and re-evaluated the task in question. I'm attaching a small leaf spring to the outside surface of the liner of a folder. I've decided to take a safer route and instead of tapping the holes I will run some flat-head screws through from the inside surface of the liner and secure them with nuts. The spring and nuts will be completely hidden under a hollowed-out space in the handle scale so I think it will all work out fine (and I won't have to buy a tap).

Thanks again. And a special thanks to PT Doc for the link to that chart, I've saved it on my computer for future use.

 

[Chuck Gedraitis Knives]

Use a 1/16 and you will break less taps. I switched to a 1.65mm for a thread forming tap.