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Thread Protector

 

I'm planning to make a thread protector for a rifle barrel.? My reference material doesn't list the drill bit size for a 1/2" x 28 TPI thread.? Can anyone help?

Pete
John Mattis
 

According to my "Machinery's Hdbk. 17 edition" for an external thread the major diameter is 0.4989 - 0.4924 and for an internal thread the dimensions are 0.461 - 0.470.
John


From: Pete Lilja
To: 7x12minilathe@...
Sent: Saturday, November 10, 2012 11:48 AM
Subject: [7x12minilathe] Thread Protector

?
I'm planning to make a thread protector for a rifle barrel.? My reference material doesn't list the drill bit size for a 1/2" x 28 TPI thread.? Can anyone help?

Pete
MERTON B BAKER
 

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That's a standard size, I think, NSF.? I think 1/4-28 is NF.
Mert
?

-----Original Message-----
From: 7x12minilathe@... [mailto:7x12minilathe@...]On Behalf Of Pete Lilja
Sent: Saturday, November 10, 2012 2:48 PM
To: 7x12minilathe@...
Subject: [7x12minilathe] Thread Protector

I'm planning to make a thread protector for a rifle barrel.? My reference material doesn't list the drill bit size for a 1/2" x 28 TPI thread.? Can anyone help?

Pete
 

I think it's listed in this old PDF printout of some website I made a while back:






Pete Lilja wrote:

I'm planning to make a thread protector for a rifle barrel. My reference
material doesn't list the drill bit size for a 1/2" x 28 TPI thread. Can
anyone help?

Pete
 

Pete, Try Paul's "Drill Sizes pdf" in the Group's Files - it's around 2/3 way down the list of files, and tapping sizes are on the third or fourth page.

Abdy

--- In 7x12minilathe@..., Pete Lilja <plilja@...> wrote:

I'm planning to make a thread protector for a rifle barrel. My reference
material doesn't list the drill bit size for a 1/2" x 28 TPI thread. Can
anyone help?

Pete
 

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WAM wrote......I think it's listed in this old PDF printout of some website I made a while back:.......
?
I don't know about anyone else, but this didn't come through for me. However, if it is a 60deg thread, then the tapping drill size is the major diameter minus the pitch, which would make this 13/28" which rounds nicely to 11.8mm dia.
Cheers.
??????? Ellis
 

That's a non-standard thread, you're probably not going to find it in a common drill size table. The easy way to figure the size is by subtracting 1/TPI from the nominal thread diameter.

Drill Size = 1/2 - 1/28 = 13/28 = 0.464

The closest common drill size is 15/32, 0.469"

Roy

--- In 7x12minilathe@..., Pete Lilja <plilja@...> wrote:

I'm planning to make a thread protector for a rifle barrel. My reference
material doesn't list the drill bit size for a 1/2" x 28 TPI thread. Can
anyone help?

Pete
 

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Roy wrote........The easy way to figure the size is by subtracting 1/TPI from the nominal thread diameter.........
?
As I mentioned in my post, this is only accurate for 60 deg threads. For those of us on this side of the pond, it doesn't work. But it can be used as an approximation, where the 'fit' is not too important.
Cheers.
??????? Ellis
 

Ok... my earlier link had the same info as this:


Second page show 1/2 - 28




Ellis Cory wrote:

Roy wrote........The easy way to figure the size is by subtracting 1/TPI from the nominal thread diameter.........

As I mentioned in my post, this is only accurate for 60 deg threads. For those of us on this side of the pond, it doesn't work. But it can be used as an approximation, where the 'fit' is not too important.
Cheers.
Ellis
 

So does this:




Ellis Cory wrote:

Roy wrote........The easy way to figure the size is by subtracting 1/TPI from the nominal thread diameter.........

As I mentioned in my post, this is only accurate for 60 deg threads. For those of us on this side of the pond, it doesn't work. But it can be used as an approximation, where the 'fit' is not too important.
Cheers.
Ellis
 

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WAM wrote......Ok... my earlier link had the same info as this ?
Second page show 1/2 - 28.........
?
And this gives quite a few different thread types, but some pages may need translating -

Cheers.
?????? Ellis
 

Thanks to all for the help in my query.

If anyone is interested here's a link to a pic of one of two similar thread protectors I made for my heavily modified Ruger 10/22. ?

I used a tap rather than lathe cutting the internal threads. ?These were pretty simple, fun projects that got my rifle looking more like I want it to look.

Pete


On Saturday, November 10, 2012, Pete Lilja <plilja@...> wrote:
> I'm planning to make a thread protector for a rifle barrel.? My reference material doesn't list the drill bit size for a 1/2" x 28 TPI thread.? Can anyone help?
>
> Pete
>

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