"Ignoramus9727" wrote in message
...
If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

Suggest download a chart.......

http://www.google.com/search?hl=en&l...rt&btnG=Search

--

SVL

..446 - .457


On 18 Dec 2004 18:49:35 GMT, Ignoramus9727
wrote:

If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

#7

Vaughn


"Ignoramus9727" wrote in message
...
If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

You can figure out any tapping hole size as follows:
-(tap drills for 75% thread)-
Take the O.D. (major diameter) of the thread and subtract 1 divided by
the pitch from it.
For example: 1/2 -20----- 0.500 - (1/20) =
0.500 - 0.050 = 0.450. Use 29/64 bit (0.453).

For example: 1/2 -13 -------- 0.500 - (1/13) =
0.500 - 0.077 = 0.423. Use 27/64 (0.422) for a good fit or 7/16 (0.4375) for
a looser fit.

Of course tables are available for this. I still use my 35 year old
Craftsman "How to run a Lathe" book for this. I have bookmarks in three
places: For the threading tables, For the decimal equivalent tables and
For the tables on diameters of numbered and lettered drills.

But I think it's good practice to work the brain now and then. Besides,
I am not always in the same place where the tables are.

Pete Stanaitis
----------------------------------------------------------------

Ignoramus9727 wrote:

If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

..446 - .457
On 18 Dec 2004 18:49:35 GMT, Ignoramus9727
wrote:

If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

Vaughn, I'm sorry, but a #7 is the tap bit for 1/4_20.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Keep the whole world singing . . . .
DanG (remove the sevens)




"Vaughn" wrote in message
...

#7

Vaughn


"Ignoramus9727" wrote in
message
...
If I want to tap a hole for 1/2"-20 threading, what hole size
should I
use? thanks

i

Ignoramus9727 wrote:

If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

29/64

"DanG" wrote in message news:YW%wd.94$ZL.33@okepread03...
Vaughn, I'm sorry, but a #7 is the tap bit for 1/4_20.

Omigosh! (blush) I should read what the post actually says, not what I
THINK is says.

Vaughn

Sorry for the duplicates - trying to learn to use a new News Reader.


"Ignoramus9727" wrote in message
...
If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

"Vaughn" wrote in message
...

"DanG" wrote in message
news:YW%wd.94$ZL.33@okepread03...
Vaughn, I'm sorry, but a #7 is the tap bit for 1/4_20.

Omigosh! (blush) I should read what the post actually says, not what
I
THINK is says.

Vaughn


Vaughn

I too read it as 1/4 20. Is it possible that the guy who posted this
question is wrong, and not us???

Jerry

Ignoramus9727 wrote:

If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

Diameter minus the thread pitch. Works with metric, too!

Cheers
Trevor Jones

In article ,
PrecisionMachinisT wrote:

"Ignoramus9727" wrote in message
...
If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

Suggest download a chart.......

http://www.google.com/search?hl=en&l...rt&btnG=Search

Or, if you have a drill index by HUOT, there is usually a chart
for tap drill and clearance drill for common threads. Not sure whether
there is anything as fine as 20 TPI for 1/2", however. The index is
downstairs, and I am not. :-)

Of course, _Machinery's Handbook_ has all the tables you could
ever need.

Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Ignoramus9727 wrote:
If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

one twentith of an inch less than one half inch. :-)
...lew...

Jerry Martes wrote:

"Vaughn" wrote in message
...

"DanG" wrote in message
news:YW%wd.94$ZL.33@okepread03...

Vaughn, I'm sorry, but a #7 is the tap bit for 1/4_20.

Omigosh! (blush) I should read what the post actually says, not what
I
THINK is says.

Vaughn



Vaughn

I too read it as 1/4 20. Is it possible that the guy who posted this
question is wrong, and not us???

Jerry


Yea. What is it with these guys that don't know to ask the right
question. :-)
...lew...

Well iffen a # 7 is for a 1/4 then you would use a #14 for a 1/2" wood't ya?
lg
Don't no how to make smilies.....

"Vaughn" wrote in message
...

"DanG" wrote in message
news:YW%wd.94$ZL.33@okepread03...
Vaughn, I'm sorry, but a #7 is the tap bit for 1/4_20.

Omigosh! (blush) I should read what the post actually says, not what
I
THINK is says.

Vaughn

"larry g" wrote in message
...
Well iffen a # 7 is for a 1/4 then you would use a #14 for a 1/2" wood't ya?

Nope. Wire guage sizes get bigger as the number gets smaller, so obviously
you would need a #3.5 drill for a 1/2". Right?

Vaughn

On Sat, 18 Dec 2004 15:26:46 -0500, "Michael Rainey"
wrote:

Sorry for the duplicates - trying to learn to use a new News Reader.


"Ignoramus9727" wrote in message
...
If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

Dear God..you are actually TRYING to use Outleak Exploder? Blink
Blink...why in God's name would you be doing that?

If you absolutely refuse to use Agent, try this free one. The learning
curve is very very small

http://www.mozilla.org/products/thunderbird/

Gunner

"To be civilized is to restrain the ability to commit mayhem.
To be incapable of committing mayhem is not the mark of the civilized,
merely the domesticated." - Trefor Thomas

Actually I was trying to use Agent. Outlook Express is what I've been
using - it's easy.


"Gunner" wrote in message
...
On Sat, 18 Dec 2004 15:26:46 -0500, "Michael Rainey"
wrote:

Sorry for the duplicates - trying to learn to use a new News Reader.


"Ignoramus9727" wrote in message
...
If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

Dear God..you are actually TRYING to use Outleak Exploder? Blink
Blink...why in God's name would you be doing that?

If you absolutely refuse to use Agent, try this free one. The learning
curve is very very small

http://www.mozilla.org/products/thunderbird/

Gunner

"To be civilized is to restrain the ability to commit mayhem.
To be incapable of committing mayhem is not the mark of the civilized,
merely the domesticated." - Trefor Thomas

On Sun, 19 Dec 2004 09:21:30 -0500, "Michael Rainey"
wrote:

Actually I was trying to use Agent. Outlook Express is what I've been
using - it's easy.

If you have questions about Agent, feel free to ask here on group..as
its very very commonly in use here.

I was looking at the headers you posted from, and it was Outleak
Exploder..so thats what I thought you were using.

Gunner


"Gunner" wrote in message
.. .
On Sat, 18 Dec 2004 15:26:46 -0500, "Michael Rainey"
wrote:

Sorry for the duplicates - trying to learn to use a new News Reader.


"Ignoramus9727" wrote in message
...
If I want to tap a hole for 1/2"-20 threading, what hole size should I
use? thanks

i

Dear God..you are actually TRYING to use Outleak Exploder? Blink
Blink...why in God's name would you be doing that?

If you absolutely refuse to use Agent, try this free one. The learning
curve is very very small

http://www.mozilla.org/products/thunderbird/

Gunner

"To be civilized is to restrain the ability to commit mayhem.
To be incapable of committing mayhem is not the mark of the civilized,
merely the domesticated." - Trefor Thomas


"To be civilized is to restrain the ability to commit mayhem.
To be incapable of committing mayhem is not the mark of the civilized,
merely the domesticated." - Trefor Thomas