Truing a barrel nut

P

PEI Rob

New member
How is this done? Several have gathered and I was thinking of truing them. The only rational thing I could come up with is to sharp V thread a stub on a slight taper. More interested in learning how to do it than a need to.
 
That's the way I do it...on a tapered thread stud. The newer nuts are so good, I just wipe them across a stone till the burrs are gone.
 
I use the proper size USA made tap (for cleaning receiver threads) between centers and stop the barrel nut with a threaded collar on the tap. I true a shop cut center in the chuck each time and drive it with a small dog, done in less time then to describe.
 
I always put em in my junk drawer and barrel the Savage like a Rem 700. Much cleaner look and easier to bed.
 
Roger rodbolt said:
I use the proper size USA made tap (for cleaning receiver threads) between centers and stop the barrel nut with a threaded collar on the tap. I true a shop cut center in the chuck each time and drive it with a small dog, done in less time then to describe.
Click to expand...

You may be able to answer a question for me. In general, how far off are they? i.e. how much of a cut does it take to have them clean up?

I was thinking of making a mandrel between centers with both sizes of threads on it and using that.

Fitch
 
Fitch,

How much they are off is similar to receiver faces in that they vary. From my limited experience I'd say they are off more on average then the receiver face on a Remington or Savage which also causes the barrel to point a direction other then the scope mount.
 
If i was going to do it i would put the barrel in the lathe and dial it in as if you are going to chamber and then put the nut on the barrel with another jam nut then cut the face of the barrel nut and then it would be true with the barrel and it will then lock up the action true with the barrel.
 
bibsmachine said:
If i was going to do it i would put the barrel in the lathe and dial it in as if you are going to chamber and then put the nut on the barrel with another jam nut then cut the face of the barrel nut and then it would be true with the barrel and it will then lock up the action true with the barrel.
Click to expand...

I under stand your point. Makes perfect sense. Carrying that a step further, I'd think the time and way to machine the nut is right after threading the tenon. Screw it on with a lock nut, machine it true to the threads. It would take just a couple of minutes and it's done. That accomplishes your goal of having the nut faced perpendicular (orthogonal) to the new chamber.

I dial the bore on the breech end to be on the spindle axis, then I machine and thread the tenon so it is coaxial with the bore and the new chamber. Having done it that way, if I was going to use a barrel nut, I could just screw it on the tenon with a jam nut and machine it true before removing the barrel.

Fitch
 
Thanks Fred. I thought of making a dedicated tool out of 4140 for both the actions and nuts but dialing it in would take as long as a making new aluminum one each time and not as true.

Guys, I think using a lock /jam nut will cock the nut and it will not be true to the threads after facing.
 
PEI Rob said:
Guys, I think using a lock /jam nut will cock the nut and it will not be true to the threads after facing.
Click to expand...

I agree. I figured that out and logged on here to post that thought and found you had beaten me to it.

A slightly tapered holder is better than the barrel. Thinking about this yesterday evening, I decided that I am not a fan of the barrel nut design for varmint rifles or any rifle requiring sub minute accuracy. I'll be truing the receiver faces and machining shoulders on all new barrels because that way I know I have a true surface for the action to tighten against.

I was going to do that anyway, but now I understand why it's a good idea. It's always better to know why.

Thanks
Fitch
 
Tapered threads

I assume those that use a mandrel with tapered threads have a CNC lathe to cut them?
 
Bibs Machine

That will probably not work, unless the face of the other jam nut and the back of the barrel nut is dead true. It will just cock on the threads as it goes against any out of square surface.

Here is what I would do. Chuck up a piece of stock an drill a hole for a 1/2 pipe thread . Thread the hole with a 1/2 inch pipe tap. Then thread the piece to fit your nut as close as possible. Screw the nut on, and insert a pipe plug. Tighten the plug to where the threads expand enough to grip the nut. Then, gently face the nut square.

If you fit the threads very close, it will amaze you how little tightenning is required on the pipe plug to gain sufficient friction to drive the nut........jackie
 
jackie

you might be right.but maybe you could put the jam nut and barrel nut on a surface grinder and true up both sides first? just a thought.
 
bibsmachine said:
you might be right.but maybe you could put the jam nut and barrel nut on a surface grinder and true up both sides first? just a thought.
Click to expand...

Unless I'm missing something, all that does is make them flat with both sides equally misaligned. It doesn't make the flat surface orthogonal to the virtual thread centerline, which is the desired result - and it doesn't do anything to make them machine true when tightened against each other.

The problem with truing the barrel nut is the need to have it true to get it to line up if it is constrained by other than "swollen" threads.

Jackie's scheme is the basic expanding mandrel trick applied to a threaded mandrel. I think it is the best scheme so far.

I'm going to avoid the whole issue on new barrels, but I may make one of the expanding threaded mandrels for both sizes of Savage threads. It wouldn't take long to do that, and I have some 1.25" diameter 12L14 just begging for the job.

I'll center it in the 4J - it will be short enough that once it's centered in the 4J it won't move around much. The jaws in my 4J are remarkably true. Rod that is centered in it points parallel to the ways within .0002" in 12" which is good enough, and frankly surprising for an imported 4J that's not had the jaws ground. I'll take it.

Fitch
 
A quick check/remedy for barrel nuts is to mount the nut on the barrel/action with some lapping compound, and gently torque it down. A fixture with an expanding thread will hold things well for rough squaring in the lathe, and hopefully your nut is then pretty square, but if it isn't, the lapping compound will show you that it isn't. A few tightening and loosenings will show a pattern on the mating pieces and also show how much out of square things are. This takes into account any thread slop. My preference is to continue to lap things in, but others may know better...

Scott
 
Why not make a new one that's true? Seems easier than trying to true up a part that could be made new and straight for a few dollars.
 
Here Is Another Thought

It does not hurt if the nut has a tad more clearance on the pitch diameter.

You could chuck the nut up, as true as possible, take a light cut on the face, and then single point the threads dead true.

I bet you could do it without taking more than a few thousanths out of the pitch diameter.

I can tell by some of the answers that many lack some of the basic understanding of machine shop practice and basic tenants of how to establish surfaces that are truely straight and square.........jackie
 
Ya made me think Jackie, thanks. If one was to make a bar [an old barrel wouldn't be straight enough] with tapered threads, thread the nut over it, use the tailstock to align the nut in the chuck. Remove the bar to true the nut threads and face. If the nut was clamped too hard it should be easy to tell by the feel when removing the bar.

Then again, simply taper threading a stub would be as fast or faster and as true as your lathe can be. I see no reason for the nut threads to be out of round or require recutting unless the nut isn't set up true before the face is cut.

Pick your poison, thanks guys,
Cheers,
Rob
 
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