Spiral Lock threads on tenon?

[boltfluter]

Anyone using this type of thread on the tennnon? Supposed to spread the load over more threads than conventional threads. Just curious .

Paul

 

[geo.ulrich]

doing a little reading from Harold Vaughn?

 

[Alex Wheeler]

Anyone using this type of thread on the tennnon? Supposed to spread the load over more threads than conventional threads. Just curious .

Paul

Yes, but there are others ways of doing the same thing IMO. Give a call if interested.

 

[BoydAllen]

Greg Tannel has, at least in the past. I have not discussed it with him in a while. Gre-Tan Rifles.

 

[Haasvf8]

Anyone using this type of thread on the tennnon? Supposed to spread the load over more threads than conventional threads. Just curious .

Paul

Being there is a lot of different threads, I am just wondering what your definition of a spiral lock thread is? Reason why I ask is I use spiral lock taps at work but I don't think that's the same thread form you guys are talking about

 

[geo.ulrich]

Yes, but there are others ways of doing the same thing IMO. Give a call if interested.

A lot easier ways than fitting a queer thread into a standard vee thread

 

[Alex Wheeler]

A lot easier ways than fitting a queer thread into a standard vee thread

LOL good way of putting it.

 

[Haasvf8]

A lot easier ways than fitting a queer thread into a standard vee thread

Yep, I guess you guys are talking about the same thread I thought you were. Not a good idea in my opinion

 

[#40Fan]

 

[mikecr]

A barrelnut works even better, as the nut pulls all threads instead of the first few threads themselves doing all the pulling. Similar to nuts pulling on studs in racing engines.
The barrelnut is also pulling the threads away from the boltface (preloading in same direction as forces challenging the connection), instead of toward the boltface.

 

[Alex Wheeler]

A barrelnut works even better, as the nut pulls all threads instead of the first few threads themselves doing all the pulling. Similar to nuts pulling on studs in racing engines.
The barrelnut is also pulling the threads away from the boltface (preloading in same direction as forces challenging the connection), instead of toward the boltface.

Guys post this often. My question is how do the threads on the shank that are inside the action know whether the shoulder is threaded on or machined on the barrel? Picture the loaded joint. That just does not make sense to me. A loaded thread joint is a loaded thread joint whether the shoulder is part of the barrel or threaded on the barrel. I used studs often in my drag engines for the benefits they offer. However loading the threads more evenly in the block was not one of them.

 

[carlsbad]

Barrel nut changes nothing.

 

[geo.ulrich]

Guys post this often. My question is how do the threads on the shank that are inside the action know whether the shoulder is threaded on or machined on the barrel? Picture the loaded joint. That just does not make sense to me. A loaded thread joint is a loaded thread joint whether the shoulder is part of the barrel or threaded on the barrel. I used studs often in my drag engines for the benefits they offer. However loading the threads more evenly in the block was not one of them.

Alex, I think you have figured it out, there is a flaw with the ramp threads. the engagement is only at the crest, this is why the tension is even the crest will give and allow for even pressure vs. a vee which contacts on flank of thread which has less give. matching vee threads will have more strength in a given application. vee threads torqued are going to be stronger. theres always someone trying to make a better paper weight.

 

[Alex Wheeler]

Alex, I think you have figured it out, there is a flaw with the ramp threads. the engagement is only at the crest, this is why the tension is even the crest will give and allow for even pressure vs. a vee which contacts on flank of thread which has less give. matching vee threads will have more strength in a given application. vee threads torqued are going to stronger. theres always someone trying to make a better paper weight.

The simple solution at least for me has been to cut a small taper in the p.d. of my tenons to try and engage more of the threads.

 

[geo.ulrich]

The simple solution at least for me has been to cut a small taper in the p.d. of my tenons to try and engage more of the threads.

Yep same as I had done, I'm really not convinced it does much. But I am not a fan of lets say tight threads as most are I'm sure you already know the reasons...

 

[carlsbad]

There is no reason to engage more threads. 60 degree threaded joints have been used in safety related applications for a very long time. There has been no reason to replace them. There are many ways to calculate thread engagement required for full strength. After you get full strength, there is no reason to add any more strength. Because you can't.

As an engineer it is funny to deal with certain codes that require significant safety margins. 100% safety margin makes sense on a beam, for example. It is easy to make the beam 2x as strong.

However, when calculating thread engagement, once you have 100% strength (won't pull out), then adding more thread engagement is a academic exercise. You can't make a threaded joint more than 100% strength like you can a beam. But sometimes the codes require it.

--Jerry

 

[JohnKielly]

Tig.

 

[Alex Wheeler]

There is no reason to engage more threads. 60 degree threaded joints have been used in safety related applications for a very long time. There has been no reason to replace them. There are many ways to calculate thread engagement required for full strength. After you get full strength, there is no reason to add any more strength. Because you can't.

As an engineer it is funny to deal with certain codes that require significant safety margins. 100% safety margin makes sense on a beam, for example. It is easy to make the beam 2x as strong.

However, when calculating thread engagement, once you have 100% strength (won't pull out), then adding more thread engagement is a academic exercise. You can't make a threaded joint more than 100% strength like you can a beam. But sometimes the codes require it.

--Jerry

I dont do it for strength. Here is my thought. If your engaging only some of the threads, potentially some are not engaged at all. At some point between engaged and not touching is a light touch. Something that could be a variable and could play a role in harmonics. Its just one of those little things I have thought of, came up with a solution for, and incorporate in my builds. It takes no extra time, costs nothing extra, and is one of those many small things I do to try and gain an advantage. Even though I dont believe there is accuracy in thread fit from what I have seen, its still something I do just in case.

 

[PWS]

There is no reason to engage more threads. 60 degree threaded joints have been used in safety related applications for a very long time. There has been no reason to replace them. There are many ways to calculate thread engagement required for full strength. After you get full strength, there is no reason to add any more strength. Because you can't.

As an engineer it is funny to deal with certain codes that require significant safety margins. 100% safety margin makes sense on a beam, for example. It is easy to make the beam 2x as strong.

However, when calculating thread engagement, once you have 100% strength (won't pull out), then adding more thread engagement is a academic exercise. You can't make a threaded joint more than 100% strength like you can a beam. But sometimes the codes require it.

--Jerry

Vaughn issue was inconsistent barrel alignment resulting from a very brief unloading of the threaded joint. He tried various methods of stabilizing the joint such as torques up to 250ftlbs, thread locker, tapered threads, forend pressure and finally settled on the Spiral Lock profile as a suggested way to fix the joint. He wasn't particularly concerned about safety or strength - except in some of the hellacious torque experiments where he achieved plastic deformation of the thread and/or recoil lug.

 

[Robert]

Barrel nut changes nothing.

Makes things more complicated and weaken the reinforce.
R.G.C