Author Topic: Powder tube thread pitch  (Read 18741 times)

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z4lunch

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Powder tube thread pitch
« on: July 20, 2012, 10:52:58 am »
Anyone no what the thread pitch is on the powder tube, where it
Threads into the top of the charge bar housing
Thanks
Steve

fc60

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Re: Powder tube thread pitch
« Reply #1 on: July 20, 2012, 01:20:27 pm »
Greetings,

The thread size is 1/4-27 F-PTF.

You will not find a tap at the local hardware store. It is a special thread.

Cheers,

Dave

z4lunch

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Re: Powder tube thread pitch
« Reply #2 on: July 21, 2012, 11:00:18 am »
Thanks Dave...
Email sent
Steve


Greetings,

The thread size is 1/4-27 F-PTF.

You will not find a tap at the local hardware store. It is a special thread.

Cheers,

Dave

askimball (Doc)

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Re: Powder tube thread pitch
« Reply #3 on: July 21, 2012, 04:48:38 pm »
Dave
Who has those for sale....??
Doc - I.Y.A.A.Y.A.S.
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fc60

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Re: Powder tube thread pitch
« Reply #4 on: July 21, 2012, 08:19:18 pm »
Greetings All,

I sent an email to McMaster Carr for a tap. I have been unable to locate one on the Internet.

I have a 1/4-27 NPT tap I was going to shorten.

I decided to set up a piece of scrap in my lathe and tap it full length with my existing tap. Bad news, it does not cut large enough.

If McMaster does not come through, I will attempt to machine a tap myself. Or, at lease a possible thread forming tool. Enough to repair damaged parts and possibly thread new ones.

Cheers,

Dave

askimball (Doc)

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Re: Powder tube thread pitch
« Reply #5 on: July 21, 2012, 09:07:05 pm »
Dave
Aren't we talking about a 'DIE'  not a  "Tap' ... ???

Die for the Powder Tube.. :D

Tap for the Powder Slide Housing Cover Plate.. :D
Doc - I.Y.A.A.Y.A.S.
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fc60

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Re: Powder tube thread pitch
« Reply #6 on: July 22, 2012, 12:06:39 pm »
Greetings,

I am working on a tap to repair a powder housing.

Cheers,

Dave

fc60

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Re: Powder tube thread pitch
« Reply #7 on: August 13, 2012, 06:38:20 pm »
Greetings,

This thread has been most challenging and educational.

Based on SAE Document J476A (1961), (link below) on page 15.22 is a section that deals with non standard threads, such as the powder hopper cover.

So, my latest calculation indicates the thread is a 9/16-27 Dryseal SPL-PTF, OD 0.563.

So far, I have machined and heat treated my "special tap". All that remains is to get it sharpened and test it out. I have screwed it into several powder slide tops and I think I have a keeper.

Another note. There is someone selling powder shutoff devices on eBay. While looking at the photos of his/her parts, the thread did not seem tapered. I wrote and asked...

"Is the threaded portion a tapered or straight thread? My existing powder
hopper has a tapered thread."


The answer I received was...

"The threads in the special fitting ,and the threads in the valve are 9/16 -
24...
streaght....it works with my press ,and have sold alot of valves
with no complants...."


I suspect that the part starts into the Powder Slide Cover; but, with continued use will damage the original threads. Buyer beware...

http://www.google.com/url?sa=t&rct=j&q=sae.j476a.1961.pdf&source=web&cd=1&ved=0CEMQFjAA&url=https%3A%2F%2Flaw.resource.org%2Fpub%2Fus%2Fcfr%2Fibr%2F005%2Fsae.j476a.1961.pdf&ei=qH4pULjyOePqiwLYr4GQCw&usg=AFQjCNHWOzTtImODBbPwqCiWMW1fQLptTA&cad=rja

Cheers,

Dave

fc60

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Re: Powder tube thread pitch
« Reply #8 on: August 25, 2012, 12:21:33 pm »
Greetings,

I finished my special tap for the #70 Powder Slide Housing Cover.

If you have a Housing Cover with a buggered thread, contact me via email and I will see what arrangements can be made to remedy the fault.

Cheers,

Dave

Stillwater

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Re: Powder tube thread pitch
« Reply #9 on: October 01, 2012, 11:17:57 pm »
Greetings,

The thread size is 1/4-27 F-PTF.

You will not find a tap at the local hardware store. It is a special thread.

Cheers,

Dave

I just checked the thread, on a Star powder magazine, that I have by my computer... My Starret pitch guage says that dave is spot on with his thread callout.

Bill

fc60

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Re: Powder tube thread pitch
« Reply #10 on: October 02, 2012, 11:24:40 am »
Greetings,

The thread calculates out to  a 9/16-27 Dryseal SPL-PTF, OD 0.563

Again, taps are not available at the local supply houses.

I also found that the #54 Steel Ball Plug is the same thread size.

Cheers,

Dave

MikeA

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Re: Powder tube thread pitch
« Reply #11 on: October 02, 2012, 07:48:19 pm »
Dave,
If someone were to remove the ball plug and taking care not to cross thread the powder housings threads could the threads be chased using the ball plug female threads?  A lot like running  a buggered bolt onto a nut if you don't have the die.Just a thought.
Thanks.
Semper Fi
MikeA
Las Vegas, NV

Stillwater

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Re: Powder tube thread pitch
« Reply #12 on: October 02, 2012, 10:01:50 pm »
Greetings,

The thread calculates out to  a 9/16-27 Dryseal SPL-PTF, OD 0.563

Again, taps are not available at the local supply houses.

I also found that the #54 Steel Ball Plug is the same thread size.

Cheers,

Dave

Dave, is it tapered also?

I just happened to have one of the Steel Ball Plugs beside me here...

The ball plug does not want to thread into the powder slide, where the Powder magazine goes. It goes about two turns and then starts binding, While the powder magazine easily threads into and goes to the bottom of the threaded area.

Bill

fc60

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Re: Powder tube thread pitch
« Reply #13 on: October 03, 2012, 12:08:16 pm »
Greetings,

I took the tap I made and was able to thread it into the hole for the ball detent. Without access to the original drawings, reverse engineering is all I have. I did not try the ball detent plug in the powder housing. Perhaps I will out of curiosity.

I calculated the density of the powder slide housing and it "appears" to be a Zinc alloy, similar to Zamak-3.

You might get lucky trying to clean up the threads of the powder slide top with the ball detent plug; but, you could end up with two damaged parts. If your powder housing top is damaged contact me about repair.

If you have access to a good Machinist, give him/her the thread specification and have a male thread machined. You might be able to iron out the damaged thread with the steel part.

Cheers,

Dave

fc60

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Re: Powder tube thread pitch
« Reply #14 on: October 25, 2012, 02:35:05 pm »
Greetings All,

While machining some Powder Hoppers, I decided to post an image of what is involved in cutting the 9/16-27 Dryseal SPL-PTF, OD 0.563 thread

http://home.comcast.net/~fc60net/TaperThread.JPG

In the photo, you can see the part is shifted off axis, by moving the tail stock away from center,  to the correct angle for the thread. (3/4" per foot, the standard pipe thread taper.)

At the very right is the brass nose piece that is inserted and clamped in the aluminum arbor.

The indicator is to control the threading operation so that I do not nick the main body of the part as the cutting tool feeds to the left.

"Maschinenvergnügen" (The joy of machining)

Cheers,

Dave