Spiral Lock Threads?

R

robertb

New member
Can someone tell me if spiral lock threads are superior to typical V threads when fitting a new barrel to an action? With that said, how many 'smiths choose to use spiral lock over conventional threads?

Lastly, say I purchase a new custom action with threads in the tenon? If I want spiral lock threads on the barrel, will threads need to be recut in the tenon of said custom action? The action would be a Borden.
 
robertb said:
Can someone tell me if spiral lock threads are superior to typical V threads when fitting a new barrel to an action? With that said, how many 'smiths choose to use spiral lock over conventional threads?

Lastly, say I purchase a new custom action with threads in the tenon? If I want spiral lock threads on the barrel, will threads need to be recut in the tenon of said custom action? The action would be a Borden.
Click to expand...

Robert, after studying the chapter on barrel/receiver joint threads in Vaughn's book, I installed several barrels using the Spiral-Lock thread, but was never convinced that it offered any real advantage over the standard V thread. I went back to the standard thread and plan to stay with it.

No changes are made on the receiver threads when using the Spiral-Lock thread; only the barrel tennon.

If I were you, I would ask Jim Borden before using the Spiral-Lock thread in one of his actions.

Just my opinion, FWIW,

Later,

Gene Beggs
 
The Spiraloc thread is a self locking thread which, like any other, depends on deformation of the thread to lock. It is hoped this deformation takes place on the barrel and not in the receiver. It is also hoped it doesn't cause the threads to gall. A good fitting V thread is likely just as stable. Regards, Bill.
 
robertb,


I'm with Gene, I'd call Jim :)


BUT.........Now that I've got a lathe I'm going to try another method (Which Harold also mentions) in an attempt to promote a more balanced lockup. What Vaughn was actually trying to accomplish with his Spiral-lock experiments was a more CONSISTENT TRANSFER of threaded joint load. Vaughn showed how the first thread in a conventionally threaded joint takes 35% of the preload, the second 23%, the third 15% and so forth until the rearmost threads are barely loaded at all. In an attempt to make all of the threads take load I propose to play with tapering the threads in a Rem style action. (I wouldn't TOUCH the threads in a Borden, :) ....yet :D ) I THINK that if one were to cut the receiver threads with about .002 (this is a WAG at best) of taper such that the thread diameter at the face of the receiver was slightly larger than at the rear then the rear threads would grab first and begin to load sooner than the front ones. MAYBE this would promote better loading, or MAYBE I'm just asking for a permanently galled together action.......this explains why I'm gonna' try it on a Remington ;)


It works to seal plumbing pipe threads...........:rolleyes:


justanotherthought



al
 
robertb said:
Can someone tell me if spiral lock threads are superior to typical V threads when fitting a new barrel to an action? With that said, how many 'smiths choose to use spiral lock over conventional threads?
Click to expand...

To claim superiority of application would mean that first you'd have to define some things about the use. Is your intent to shoot one group, or, to shoot many and have a long term competive rifle?

If you intend to solve a problem, you first need to know what the problem is. They're a bit tough to solve without knowing that. What exactly is the "problem". The thread you speak of is definitely stronger, but, did you ever see a barrel with a stripped thread? Does this thread offer more total surface engagement? Is that even something we're looking for?

All good questions.

I think it is anyones guess how many "smiths" use these threads. I would say that number is very very few. In my early attempts at gun building, I tried a few different methods of threading. About all I could say for sure was that I could spend a lot more time on the threading with no visible gain. I had no problem to solve so, solving it was tough.

Lastly, say I purchase a new custom action with threads in the tenon? If I want spiral lock threads on the barrel, will threads need to be recut in the tenon of said custom action? The action would be a Borden.
Click to expand...

For the sake of proper terms, a receiver does not have a tenon. That's on the barrel. The receiver has a receiver ring, threads, etc. A tenon is a part that protrudes.

As a rule with this thread, only one part gets the thread with the additional material in the root. That thread more or less lives forever. The other part, has a standard V thread and that thread yields upon compression. So, that part after being installed one time will no longer be the same. The tops of some of those threads will be smashed over by design (those closest to the barrel face).

Harold in his book clearly had a problem to address and with this thread, he addressed it. He was using a wimpy action that was like, clinging to the barrel with it's fingernails. He had already cut the thing till all that was left was a potato chip. It stands to reason, anything at that point could be shown to help.

I use standard V threads on all my guns but I'm also not working with a Remington 721 like Ole Harold was. I don't think in the case of todays custom actions, that this thread could be shown to be of any advantage. jmo. I would guess that if someone on this board actually has found them to offer an advantage, they won't tell you here. Furthermore, even determining if they did offer an advantage would be a difficult job. With as well as the guns built for benchrest already shoot, showing the miniscule improvement shown by the Sprialock thread would be tough.

Also don't forget, Harold in his book was dealing with a tenon that was only .680 long. Most of the guys here are working with actions that have a thread length of 1" or greater. These are completely different animals from a Remmy. They also have about double the material around that tenon and that extra beef makes up for a lot of thread technology.

Remember, the premise of this thread is to spread out the contact area. It does not say anything about having MORE contact area. Just that less load is on each thread. If your action has an issue with the strength of it's threads, this thread will almost definitely help. The gun still goes bang, and there's still the same forces on the barrel/receiver when you pull the trigger. Harold showed in his book that there was a significant increase in the force required to remove the barrel after firing when using that thread. My guns don't have that problem. They're just the same torque after 2 years as they were day one (within my ability to estimate/measure).

Of the smiths I have ever talked to who bought the tools to do this thread (3), none of them say they do barrels that way.
 
4mesh,


Harold's work did change the way I look at the "long tenon" situation.........if only the first 6-8 threads are actually loaded then the length of the shank does essentially nothing, except add weight.


justathought



al
 
4Mesh, that is an indepth and well written response. You can't get more thorough than that; well done.

Gene Beggs
 
As I understand it, the problem that Vaughn identified was that the barrel was not always "returning" to the same point in the receiver. His test was to mount a second scope on the barrel, and he discovered that occasionally, the barrel scope went to a different position than the receive scope after firing. The next shot printed at a different point on the target.

Since there was a joint between the barrel & receiver, he went after that joint.

If this problem can be found in a benchrest gun, the straignforward solution is to mount the scope on the barrel. That way, the barrel and scope are always pointed in the same direction. This can be done by using a barrel block, making a base that cantilevers back over the action, and putting the scope base on the block. The penalty is weight. I've done this on a HV, shoots fine. It does seem to have fewer mystery shots. But there is no proof the scope mounting is the reason.

As 4Mesh says, you first have to determine if there is a problem.
 
Collar instead of threading barrel

Vaughn talked about using a collar to lock the barrel to the receiver. This would allow you to clock the barrel to see if it liked a different position. Has anyone tried it?
 
Spiralock thread

alinwa said:
robertb,
It works to seal plumbing pipe threads...........:rolleyes:


justanotherthought



al
Click to expand...

Hi Al.
I read Vaughn's piece on Spiralock and looked into the design a little. The shadowgraph, which showed the loading of the threads, was very impressive. As in all things mechanical, there are specific designs for specific applications. If memory serves me well the Spiralock design is superior in highly cyclical or vibration rich environments, as in aircraft applications. While superior in one type of application, it may yield no additional added benefits over traditional threads. Vaughn's concept was valid but is the cost/benefit ratio worth the extra expense for rifle accuracy?
Chino69
 
I believe that Greg Tannel of Gretan Rifles uses the Spiralock thread, and has for some time. You might give him a call.
 
Just My Opionion

As far as I am concerned, the use of such gimics as spirolock threads on the tenon of a Benchrest Rifle is a total waste of time..........jackie
 
Perfect Action!

robdaniel said:
Vaughn talked about using a collar to lock the barrel to the receiver. This would allow you to clock the barrel to see if it liked a different position. Has anyone tried it?
Click to expand...

Rob,
I have been wracking my brain for years trying to come up with a good way of doing this. I have even hinted around on this forum to the various action makers to go to work on the design, but if any took the hint, they are keeping it to themselves. It may be that the design shown on page 119 of "Rifle Accuracy Facts" by Vaughn is the way to go. I'm thinking that the answer lies in something like the Savage barrel nut.

Vaughn's design is pretty close, but the thing that has always bothered me about it is that tiny little threaded ring at the front of the receiver that holds the barrel in place. How would you get a good grip on that thing to tighten it? I know, I know,,on page 120 it shows the ring has holes drilled in it for a spanner, but I still don't like it. I suppose you could make the forward part of it longer so you could place it in the barrel vise; that might work. I have never built one like this, but plan to experiment with it in the future.

During the past few years, I have dreamed up what I believe would be the perfect benchrest action.

A receiver made of aluminum with the scope mount dovetail integral with the action. This eliminates any concern for alignment or security of the bases. The Kelbly Panda is perfect in this regard, but I wish it was available with a hard anodize finish like the Stiller actions. I love my Viper and Cobra drop ports, I love the hard anodize finish and the coating on the bolt body and handle that makes them soooo smoooth! And the drop port feature is simply unbeatable! Since Stiller has a patent on the drop port, I guess my dream action will have to be built in his shops.

The Viper and Cobras that I'm presently shooting are my all time favorites, although if I could have it ALL, I would wish for the following:

1. A 30 degree coned breech. I know, I know,, you can't have that and use that great Remington extractor, but I'm just dreaming. By the way, if you have any concern about the reliability of that Remington snap-in extractor, forget it, that thing is bullet and fool proof!

2. A barrel/receiver joint that permits easy indexing of the barrel as discussed in the first part of this post.

3. Firing pin travel of .250.

That's it! I know I'm dreaming but, what the heck; I can dream; can't I? :D

Gene Beggs
 
Al,

Concerning the longer tenons, If you think through what happens as Harolds thread load scenario plays out, that if the tenon has stretched enough that it unloads thread 4/5/6, it will also have stretched enough to reverse load threads 8/9/10 (or you get the idea). Provided of course the thread is not made with a mile of slop on the pitch diameters. I think in the case of most gunsmiths, they make barrel threads pretty much on the high side of the tolerance for a class 3 thread. I know mine leave very little room, but they're not overly close as to cause assembly issues either.

Tapered threads... Didn't Harold mention in his book something about a serious design issue with the tapered threads? Perhaps I'm remembering wrong. I was under the impression that he said there was some major mis-application problem with them but again, I may be mistaken. I don't even remember where that book is anymore.

Oh, and Al, Where Harolds design worked well you have to consider the differences between his rifles and a benchrest rifle.

First, he was using a remington with a 24" sporter weight barrel and factory stock. His amount of weight hanging on those short threads was considerably different than someone here with an 1.250 or 1.450 barrel hanging 30" out from the receiver (completely unsupported) and firing up to 20 shots at at time (getting scored on the last 5 or 10). Big difference.

Second, don't forget that every time Harold wanted to see if a problem was related to his gun or to his ammo, he went and grabbed a rail gun and shot the ammo in that. It's not like he didn't have a solid reference point to work with. Well, that rail gun didn't have spriralock threads in it! hehe. It was just a BR gun that shot because of it being a vastly different design. It was designed to be accurate, unlike the one he was working with that was designed to do not much more than go bang.

Jackie, that's about as outspoken as I've seen you here! Good Job! Lol

Gene, your dream action is waiting for you at the local steel supplier. Go buy a 1-3/4 hunk of 17-4 and a 1-1/4 bar of 4340 and get whittl'n. I also had an idea for a "dream action", cept, I just wasn't willing to wait for someone else to make it. (ps. it has v threads in it)
 
Thanks for all of the information/advice...I apologize I had my nomenclature wrong (tenon, receiver ring, etc.) It looks like you guys translated what I was asking.
 
threads and other smoke X witch oil

At over $200.00 a insert, that cut external threads,that the chief application engineer would not sign off on, could be a problem if something went wrong. Do to the 30 deg. root loaded side of thread shank major dia. is smaller. This application Pat. was intended for internal threads only. Not here to rock the boat,just want to row it a little. Like a good friend of mind said. (I think I can smell the fumes) please don't call the teacher.
 
#2 dis tat and utter Threads and other smoke X witch oil

there are actions on the market that have taper narrow in rear,just start checking, maybe you might own one.
 
I've thought about that issue after reading Harold's book and my understanding was there wasn't enough centering torque to securely lock the barrel in a fixed position, meaning it was able to cant a bit. With today's methods of trueing actions and ensuring everthing was square certainly would seem to correct that problem. BUT I've considered adding a 45 degree chamfer to the face of the action and a like angle at the tenon shoulder the barrel would center in and seat. I think there was mention of the same thing in the Houston Wharehouse article. Someday I'd like to machine my own action and if or when I do, I'd make two 45 degree chamfers, one at the action face, and one down at the end of the threads. Two 45 degree shoulders with threads in between seems like a rock solid lock-up to me. The shoulder at the barrel tenon/shank would also have a 90 deg surface. It would be a little tricky to get the dimensions machined properly for solid contact on all surfaces, but in my mind it would be a very solid arrangement.

This obviously wouldn't work with a sandwiched recoil lug arrangement though.

This is just 2 cents from my theoretical side vs. actual experience though.
 
alinwa said:
Chino69,


My post wasn't referring to Spiral-Lock but to tapered.


al
Click to expand...


Yes, I know Al. Pipe threads are tapered to seal and serve a different function than a component that will be threaded and unthreaded. When making up pipe threaded connections, the male end requires eleven threads with seven of those being full engagement threads. I don't know if those seven are loaded equally but they do form a wedging action when tightened. This magic number seven comes into play in calculating piping offset and pipe fitting. Pipe connections are not meant to be taken apart once made up as there is a degree of deformation involved; again the purpose is a leak tight connection. I'm not aware of a tapered threaded connection other than pipe and would be curious if one exists or any experimentation one has performed.
Chino69
 
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