Information for the amateur

[benmychree]

There is no one size for the drill for a tap, it varies with material and % thread required

I have worked at the trade since 1964 and owned my own business for over thirty years, and have never had to worry at "picking nits" as you suggest; 75% thread is good enough for nearly any use.

 

[magicniner]

I guess you'll be having no truck with classes of threads then? ;-)

 

[David S]

Guys I think this was just meant as a quick tip for those less endowed with all sorts of stuff, and not building aircraft.

David

 

[magicniner]

My point was that the standard recommended drill usually yields more than 75% threads and can be problematic in Stainless or harder materials.
The suggestion that "One size fits all" is patently the wrong answer, even if you get away with it.

 

[Giles]

Guys I think this was just meant as a quick tip for those less endowed with all sorts of stuff, and not building aircraft.

David

Exactly--not rocket science--Thank you for understanding my post.

 

[Tony Pisano]

You guys all got it wrong. You're supposed to have all of that tap drill info in your head. No such thing as internet and smart phones during my early days in the shops. We memorized all of the fraction drill sizes and all of the common tap drill sizes. checked a wall chart or machinists handbook for backup.

 

[David S]

My point was that the standard recommended drill usually yields more than 75% threads and can be problematic in Stainless or harder materials.
The suggestion that "One size fits all" is patently the wrong answer, even if you get away with it.

Magic, sorry I didn't mean to dispute your advice. It felt that this thread may have been going sideways from the original intent. Of course there isn't a one size fits all on some of these things. There are certainly conditions that don't fall into the "general rule of thumb".

David

 

[benmychree]

I guess you'll be having no truck with classes of threads then? ;-)

Where appropriate, yes, but for 99% of what most of us do, the standard 75% is just fine.

 

[RollingPin]

You guys all got it wrong. You're supposed to have all of that tap drill info in your head. No such thing as internet and smart phones during my early days in the shops. We memorized all of the fraction drill sizes and all of the common tap drill sizes. checked a wall chart or machinists handbook for backup.

That might have worked at one time but since I’m 72 it doesn’t work now. At my age my mind is too full of bs like passwords and user names.


Sent from my iPad using Tapatalk

 

[T Bredehoft]

I h ad an instructor once who was fond of saying "I'd hate to drive over a bridge built from memory." Meaning, "Look it up don't try to remember everything."