drill bits

[BURN]

Hi,
could someone tell me what size/number of bit I use to start/make a hole for the 0-80 tap....??

 

[richtrix]

Hi Paul, a #56 or a 3/64" both are just a little over .046 ........either will work fine.......Richie

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"Trust everybody, but cut the cards."

 

[Bruce Jensky]

I recommend you use a 3/64th" drill for a #0-80.

A 3/64th" drills a 0.0469 hole for a 75% thread pattern. Machinery Handbook recommends a 75-80% thread for machine screws.

A #56 drills a 0.0465 hole and that might be just a bit too tight and you will probably break off the tap. If you check some of the old notes in the forum, you'll see notes on the subject of busted taps...

Used a tap lubricant, go slow, cut no more than 1/4 turn and back out 1/2 turn. After 3 turns, back out the entire length to clear the threads and you will never break a tap.

Good luck and good tapping...

Bruce Jensky

 

[BURN]

Thanks.

I used the die for the tap and broke two of the only taps I had with it

. Will have to wait a week to try again but I'm going to tap them without a die this time. I didn't even make it into my liners with the tap before both of them broke off.