Tapered tenons?
- Thread starter alinwa
- Start date
I am not sure tapered threads have all that much more thread engagement.
Most threaded joints have only a very few actual threads engaged.
Sealing against pressure is not the same as thread engagement.
Tapered (NPT) is relegated to pipe threads for good reasons.
Most threaded joints have only a very few actual threads engaged.
Sealing against pressure is not the same as thread engagement.
Tapered (NPT) is relegated to pipe threads for good reasons.
Last edited:
Wayne Shaw
Active member
If I'm not mistaken, when Stiller started making his Viper and Python, his paperwork stated the inside threads had 7 tenths taper, tighter toward the bolt. That was a long time ago, I may be mistaken.
No, you are correct.....Jerry is a bright man
He did for the same reason I would choose to taper a tenon.
And I believe he quit doing it because people reacted negatively to it..... in complete ignorance.
I'm guessing you tested it with a PPC or the like. I don't think it could make any difference on a small round. Shucks, most PPC setups are only tightened to 50ftlb
The big chamberings do offer some different challenges. As I've tried to illustrate before, once you start catching BIG fishes, once you start running 18-20-30lb drag pressure, you gots to learn all over again how to tie your fishing knots...... the old "Trilene Knots" and "Palomar" and "Clinch" and such go right out the window..... and in the same way, BIG chamberings IMO make things show up that aren't issues with smaller chamberings
My big goal right now is a 600yd setup that allows me to see bullet holes on the blue target....getting a 338 to shoot like a "Dasher" is a BIG challenge
Pete Wass
Well-known member
In the "Sniper World"
What are the folks who make those rifles doing? I am assuming to shoot at the distances they do at a human, they need to have some kind of reasonable accuracy and need to know, pretty much, where their bullets are going?
Having said that, I noticed one of the winners at the recent Southwest Nationals was shooting a 308.
Pete
What are the folks who make those rifles doing? I am assuming to shoot at the distances they do at a human, they need to have some kind of reasonable accuracy and need to know, pretty much, where their bullets are going?
Having said that, I noticed one of the winners at the recent Southwest Nationals was shooting a 308
.Pete
Dave Tooley
Active member
I know a little bit about what's being used. Most, if not all, are not capable of shooting the difference. Tier 1 groups have basically custom built rifles. They have smiths who take care of their barrel work. One I'm familiar with carries 338 Lapua's. Not the most accurate round. The actual number of rifles is smaller than you think. The tier II guys, SF , MARSOC, Seals etc have custom barreled rifles like the Mk13. Which while it has a custom barrel is more of a production item because of the larger numbers involved. Then the knuckle draggers have Remington production 700's. The M2010 . Soon they will transition over to the Barrett Mrad multi caliber system. That will be fun to watch. "Son here's your 25 rounds of 300 Norma Mag ammo for training this year"
Oh tapered tenons. No on all the above.
Oh tapered tenons. No on all the above.
Pete Wass
Well-known member
What are the folks who make those rifles doing? I am assuming to shoot at the distances they do at a human, they need to have some kind of reasonable accuracy and need to know, pretty much, where their bullets are going?
Having said that, I noticed one of the winners at the recent Southwest Nationals was shooting a 308
Pete
"Sniper World"
"reasonable accuracy"
IME with this crowd 1.5moa is top-o-the-pile altho they call them "1MOA" cuz "3-shot groups" and "averages" and "means" and "pulled shots" and "bad wind calls" and "throw out high and low" and all sorts of other Magical Mathematicks.....
MilGunsmith
Member
We were doing the acceptance testing on the.300WM M2010 rebuilds here for a while and the requirement was for 2MOA 10 shot groups at 300 meters. Not very good, my shop reworked some of the failed guns and got them into the 1.5MOA range using the supplied barrels. The barrels were Remington supplied with bad or off centered crowns, we had to pick through the supplied barrels to find any that we could use. The barrels were nitride coated, which I don't think helped accuracy.
Interesting. I have no doubt that on paper it works.. I remember reading Harrold Vaughns book which had a detailed chapter on thread engagement. However i think "a few tenths" of taper would be lost in the drive train and backlash of most manual lathes.. Add in a bit of uneven wear of the lead screw on an aging machine and who knows what kind of actual thread engagement one actually achieves?
If tenons were threaded on a well maintained high end CNC then that perhaps would be a different ball game, but on your average used tool room manual lathe, i'd be surprised if it made much difference..
Cheers
Lee
Dave Tooley
Active member
The majority of the time you get some taper from work piece deflection.
"not on my lathe, with my setups!!!"
lol
Which is adjustable, usable and somewhat repeatable
depending on;
-extension from chuck ("overhang")
-diameter of tenon/taper/bbl
-carbide VS HSS tooling
-threading inside-out produces a different taper than threading toward the headstock
-offset of tailstock is also an option
And we're not necessarily talking tenths here in my case. Couple thou of taper is easily realized manually and very repeatably....and on the tenon side consisting of raw fresh-cut threads (VS the action side of CNC cut, burnished and most often with a hardened surface) there is more smear, distortion, compression. In real life it's possible to do work such that one can FEEL thread engagement occurring before the shoulder abutment touches down......
Contrary to popular belief CNC equipment is not "more accurate" than manual equipment as much as "real machinists" would like to think it is. (("Real Machinists" also believe in rigidity as the be-all and end-all of accuracy LOL))) Confirming work over wires is the same whether you programmed it or whittled it with a 3-corner file. As long as surface finish is analogous.
BTW I'm reasonably sure Stiller was well aware of the doubling effect of him tapering receiver threads for barrels which are quite normally flared to begin with.
And btw what Leeroy is actually saying is "Al, yer foolin' yerself" and I get that.
doesn't make it TRUE
Which is adjustable, usable and somewhat repeatable
And btw what Leeroy is actually saying is "Al, yer foolin' yerself" and I get that.
doesn't make it TRUE
Yeah you got me AL.. I was having a little poke at the whole concept but i didn't mean anything by it.
I've a great deal of respect for the posters in here and i am happy to admit there are folks out there who are way smarter than me and are doing things for reasons i probably don't understand properly. So for my own (and others) edification, what are the benefits of a tapered thread junction on barrel/receiver joint over a standard parallel thread? (Genuine question).
Cheers
Lee
As Harold Vaughn illustrates visually here
The way threads work, the way threads MUST work due a simple thing called "stacking tolerances" is such that unless one can reduce stacking tolerances by introducing a progressive engagement method of some sort it's physically impossible for the deep threads to have anything but air between them.
This is easily proven by the introduction of oil into the front VS rear screw holes on certain action rings. Or by the simple expedient of making a threaded fixture (threaded lamp rod works for this)
Look at how a chain drive works, or watch the tracks on a dozer under a heavy load........
I am currently building several BMG's and one of the actions was designed with no thought for "form" nor to accommodate anyone's preconceptions but from calculations.
Here's how many threads are on this monster!
Scary
But the FACT is that no matter what I think of it, it's adequate.
Many things like the length of the tenon on a rifle action are set to standards based on misperception or "common knowledge"...
What I mean is..... A LOT OF PEOPLE make decisions based on supposition with zero supporting data..... For instance I know of people who will tout a certain manufacturer of action over another because "so-and-so has a longer tang". And BTST I know of people who think and actually state out loud that "Kelby's make their tangs too short". These same people will pick on Tiger Woods' golf swing...
I don't make decisions this way.... I'm incapable of it. If I've learned one thing over the years it's that "stands to reason" and "common sense" and "everybody knows" are generally WRONG
The way threads work, the way threads MUST work due a simple thing called "stacking tolerances" is such that unless one can reduce stacking tolerances by introducing a progressive engagement method of some sort it's physically impossible for the deep threads to have anything but air between them.
This is easily proven by the introduction of oil into the front VS rear screw holes on certain action rings. Or by the simple expedient of making a threaded fixture (threaded lamp rod works for this)
Look at how a chain drive works, or watch the tracks on a dozer under a heavy load........
I am currently building several BMG's and one of the actions was designed with no thought for "form" nor to accommodate anyone's preconceptions but from calculations.
Here's how many threads are on this monster!
Scary
But the FACT is that no matter what I think of it, it's adequate.
Many things like the length of the tenon on a rifle action are set to standards based on misperception or "common knowledge"...
What I mean is..... A LOT OF PEOPLE make decisions based on supposition with zero supporting data..... For instance I know of people who will tout a certain manufacturer of action over another because "so-and-so has a longer tang". And BTST I know of people who think and actually state out loud that "Kelby's make their tangs too short". These same people will pick on Tiger Woods' golf swing...
I don't make decisions this way.... I'm incapable of it. If I've learned one thing over the years it's that "stands to reason" and "common sense" and "everybody knows" are generally WRONG
As Harold Vaughn illustrates visually here
View attachment 25406
The way threads work, the way threads MUST work due a simple thing called "stacking tolerances" is such that unless one can reduce stacking tolerances by introducing a progressive engagement method of some sort it's physically impossible for the deep threads to have anything but air between them.
This is easily proven by the introduction of oil into the front VS rear screw holes on certain action rings. Or by the simple expedient of making a threaded fixture (threaded lamp rod works for this)
Look at how a chain drive works, or watch the tracks on a dozer under a heavy load........
I am currently building several BMG's and one of the actions was designed with no thought for "form" nor to accommodate anyone's preconceptions but from calculations.
Here's how many threads are on this monster!
View attachment 25407
Scary
But the FACT is that no matter what I think of it, it's adequate.
Many things like the length of the tenon on a rifle action are set to standards based on misperception or "common knowledge"...
What I mean is..... A LOT OF PEOPLE make decisions based on supposition with zero supporting data..... For instance I know of people who will tout a certain manufacturer of action over another because "so-and-so has a longer tang". And BTST I know of people who think and actually state out loud that "Kelby's make their tangs too short". These same people will pick on Tiger Woods' golf swing...
I don't make decisions this way.... I'm incapable of it. If I've learned one thing over the years it's that "stands to reason" and "common sense" and "everybody knows" are generally WRONG
Well yes of course, i read Vaughn'd book as well, and without a doubt both you and he are correct about the increase in thread engagement.
No doubt that in your specific circumstance, with such a large cartridge, and such a short tenon that having more (or all) of the threads make contact would be a worthwhile endeavor, at least in terms of added peace of mind.
Perhaps a better question to ask then is, for an average 1.062" x 18 or 16 TPI tenon, do you think that increased thread engagement will result in a stronger or stiffer joint, considering the relatively low torque we use to put barrels on? And more importantly, would that translate into measurably better accuracy/precision?
Cheers
Lee
GeneT
Active member
Spiralock
So why not just go with the "Sprialock" thread that was Vaughn's solution? IIRC, the company that owns the Spiralock name only makes cutters for female threads, but you could sure grind a cutter for male threads (which they made back when Vaughn was published...). I'm assuming here that you have control over the barrel, but not the receiver.
GsT
So why not just go with the "Sprialock" thread that was Vaughn's solution? IIRC, the company that owns the Spiralock name only makes cutters for female threads, but you could sure grind a cutter for male threads (which they made back when Vaughn was published...). I'm assuming here that you have control over the barrel, but not the receiver.
GsT