Jackie's pics

Dennis

In general thread applications, such as standardized Nuts and Bolts, the length of the nut is no longer than the diameter of the thread. As an example, a 1/2 inch nut is generally 1/2 inch long, a 3/4 is 3/4 inch long, etc. This even carries up to the large nuts we make and use, a 5 inch diameter 4 tpi nut will be 5 inches long.

I suppose that under this general line of thinking, a 1.062 diameter thread should be 1 1/16 long to have maximum strength. Of course, by maximum strength, I mean that the thread will hold as much as the piece if material that it is threaded on.

I have overloaded pull studs, and the threads rarley fail. It is the piece if material that finally breaks.

One example of this happenned a few years ago. One of our Shipyard Customers was installing a large propellor shaft bearing. The Shell of the bearing is brass, was bout 15 inches in diameter, and 45 inches long. We fit the bearing to have an average .003 press fit. It should have taken about 120 or so tons of pressure to install it.

The shipyard has a 200 ton Hollow Ram Jack. It has a 3 1/4 hole in the center for a good reason. The workers, (the night crew, as it was), used one of their 2 inch pull studs instead of their 3 inch.. As the bearing was going in, the stud snapped just about when you would have expected it to. The nut assy flew about 30 yards out the back.

The thread did not fail. The stud pulled in half, about 12 inches in.

I have plenty of old barrels laying around. I could do what you propose with not much effort.........jackie
 
Donald said:
Gene,
Have you decided on a final size for your insert?

Donald
Click to expand...


Donald, I have not been doing anything with the index bushing project in the past few weeks. My time has been consumed by the 'Ultralite' stock project. I'll get back to the indexing project as soon as possible.

Bill Myers has been very successful with the differential thread bushing in his rimfire rifles. It's a natural for rimfires, but I am not ready to go into production with the centerfires. I am still shooting the original prototype which uses a .940 tenon in a Stiller Drop Port action chambered in 6mm Beggs 269 neck. It shoots terrific and no problems have been encountered but I would like to do more testing before putting them on the market.

Later,

Gene Beggs
 
Thread strength..question..

When looking a action thread strength..I guess I am missing something...in the event of a high pressure load effect on a rifle action...I would think that the threads would only be affected if the pressure thrust was only in line with the threads...Most of the rifle damage due to blocked bore and or over pressure load blows the receiver apart in direction of least resistance...and most of the time in all directions...as most detonations/explosions are omnidirectional...
In otherwords thread strength is only a part of the strength equasion...
 
eww1350 said:
When looking a action thread strength..I guess I am missing something...in the event of a high pressure load effect on a rifle action...I would think that the threads would only be affected if the pressure thrust was only in line with the threads...Most of the rifle damage due to blocked bore and or over pressure load blows the receiver apart in direction of least resistance...and most of the time in all directions...as most detonations/explosions are omnidirectional...
In otherwords thread strength is only a part of the strength equasion...
Click to expand...


go back to the begining....."this may be a silly question" post...

this was not about blowing up actions..it was about thread strength, specifically a 16/18 rework thread.
 
Mike

Was the thread that Jackie tested a 18 TPI, then recut to a 16 TPI?

I don't see where this thread started.
Please help.
 
Keith23 said:
Was the thread that Jackie tested a 18 TPI, then recut to a 16 TPI?

I don't see where this thread started.
Please help.
Click to expand...


the original thread is "May be a silly question"
its down about 20 lines or so on the gunsmith page

no, just go read all of both threads
 
Thanks Mike

You pointed me in the right direction.
It was an 18 tpi re-cut to 16 tpi.

"I then took an old unlimited barrel that is threaded for the Viper on my Rail Gun, which is 1.062 18 tpi. I cut the barrel off to 8 inches, and put the 1.125 12 tpi on the cut off end. I then established a 16 pitch thread on top of the existing 18 pitch thread, exactly the way I explained it in my first post on this thread. "

Who knew it would be that strong? Jackie apparently!
 
eww1350

Go back and read both threads in their entirety. I would like to know what you think as a unbiased onlooker........jackie
 
As an unbiased reader of the thread...I am going to keep my thoughts to myself and let the readers/participants share their thoughts...I don't want to be perceived as challanging your test results as they were realistic for the application of tensile strength testing.
But, I would like to see photos of a high pressure rifle blow-up that literally spit the barrel forward out of the action by stripping the threads...and caused no other damage to the metal parts of the rifle..
 
Have you heard of such a failure? I have not. That was sort of the point of my earlier post. Even when slightly reduced in strength, they are far from the weakest link.
 
me thinks you simply need to do a search on the web. lots of pics out there.

but...not seen what you ask,,,,how would a bbl splt, and pull out of the threads ??

typical is just a bannana peel of the bbl, with the recver intact. i can see one or the other but not both.....

rcver fails and spits bbl forward....

cannot see spitting bbl forward and then spliting bbl.....


mike in co
 
Mike in CO

The word I used is "SPIT" meaning thrust the barrel out of the action stripping the threads in the process...I knew better than to reply to this thread..:(
I was trying to point out that I have never heard of action threads failing during a high pressure blow-up..and tried to describe it in the terms of the barrel threads failing and allowing the barrel to be thrust out of the action..
Therefore in my lowly opinion thread pitch 14,16,18,20 is not relavent to safety during a pressure blow-up...Just a preference by the action maker.
Thread to thread lockup strength is merely a tensile strength factor..
 
eww1350 said:
The word I used is "SPIT" meaning thrust the barrel out of the action stripping the threads in the process...I knew better than to reply to this thread..:(
I was trying to point out that I have never heard of action threads failing during a high pressure blow-up..and tried to describe it in the terms of the barrel threads failing and allowing the barrel to be thrust out of the action..
Therefore in my lowly opinion thread pitch 14,16,18,20 is not relavent to safety during a pressure blow-up...Just a preference by the action maker.
Thread to thread lockup strength is merely a tensile strength factor..
Click to expand...


very good sir......i agree.
 
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