Barrel Nut Truing
- Thread starter zp3design
- Start date
S
squeakie
Guest
I for one will be following this thread as I know of no easy way to get it done. I took a hand full of the nuts one time and compaired them, and about .0015" varition in the pitch diameter (in OTW .003"). The only way I could figure out to get past this was to build a "hydra-loc" arbor that was threaded, and pray it would expand the needed amount. Never got time to finish the arbor, but I'm certain it's doable. In the end it was easier to just make a new nut.
gary
Bob Kingsbury
New member
You can of course do away with the nut
Damn search function isn't working very well, I was starting to think I was losing it.
http://benchrest.com/showthread.php?61000-Truing-a-barrel-nut&highlight=
http://benchrest.com/showthread.php?61000-Truing-a-barrel-nut&highlight=
Niccolo M.
Member
Greetings,
Dump the nut, fit the barrel with a shoulder and use a good quality thicker recoil lug. This is the way it is done in our shop and we have never had a customer come back to ask that the shoulder be removed and a “nut job” performed on his barrel.
Nic.
Dump the nut, fit the barrel with a shoulder and use a good quality thicker recoil lug. This is the way it is done in our shop and we have never had a customer come back to ask that the shoulder be removed and a “nut job” performed on his barrel.
Nic.
Bob Kingsbury
New member
Although in the scheme of things, we would like to true everything, it may not be needed.
I say this because something like a savage barrel nut would be made in one CNC set up.
In other words, the bore, threads and shoulder would likely be made perpendicular and square, then parted off at the small end. This probably leaves that part as true as it is going to
get.
I say this because something like a savage barrel nut would be made in one CNC set up.
In other words, the bore, threads and shoulder would likely be made perpendicular and square, then parted off at the small end. This probably leaves that part as true as it is going to
get.
S
squeakie
Guest
Gonna take a big pipe plug when your looking at a 1.05 thread. Use a light grease or heavy transmission oil in the arbor to expand it. I was planing on using a piston with a quad ring seal, that was being pushed with a .50-20 set screw. I'd think a 15/16" bore would be about right. Hydralock arbors are very accurate when built right
gary
N
NesikaChad
Guest
Bob,
To answer your question I think an expandable mandrel is the best idea for a number of reasons. As I read your title it's the first thing that occurred to me as my little OCD mind began churning through the question.
Reasons your probably already aware of:
1. Threading the unit onto something with a shoulder would probably work but if the face is out on the backside it's going to want to "kink" as the threads tighten up.
2. Grabbing it in a chuck/collet doesn't ensure the threaded portion is square to the face. It just makes the faces square to the OD.
If it were me I'd thread a male 5C collet that is expandable via the little screw in the center and then cut a relief with a parting tool on the backside of the barrel nut. This way you only change a tool and not the part setup. Just ensure your threads are parallel to the spindle axis (notice I didn't say concentric as in this case its really of little consequence) and give her hell.
Great question and great idea for those who choose to use the nut to snug up the barrel to an action.
To answer your question I think an expandable mandrel is the best idea for a number of reasons. As I read your title it's the first thing that occurred to me as my little OCD mind began churning through the question.
Reasons your probably already aware of:
1. Threading the unit onto something with a shoulder would probably work but if the face is out on the backside it's going to want to "kink" as the threads tighten up.
2. Grabbing it in a chuck/collet doesn't ensure the threaded portion is square to the face. It just makes the faces square to the OD.
If it were me I'd thread a male 5C collet that is expandable via the little screw in the center and then cut a relief with a parting tool on the backside of the barrel nut. This way you only change a tool and not the part setup. Just ensure your threads are parallel to the spindle axis (notice I didn't say concentric as in this case its really of little consequence) and give her hell.
Great question and great idea for those who choose to use the nut to snug up the barrel to an action.
M
Mrgunslinger
Guest
If you have the means to true up the nuts,then why not just make new ones?
That way they would be true.
Alittle more work but you know what you have when finished.
That way they would be true.
Alittle more work but you know what you have when finished.
I ran all these ideas through my head when I accumulated a few barrel nuts. What I decided to do was to turn a piece of stock to 1.055 diameter x 1 1/4" long. Then I threaded it for a good fit 5/8" long. Then I screwed the nut on until the thread in the nut bottomed out on the tread that I chased. Snugged it up as tight as I could by hand, then took light cuts (a couple thou @ a time) until it cleaned up. Usually .004 or less to get 100% clean up. This way you don't have to worry about anything being in contact other then the threads but they have to be a good fit. Simple easy inexpensive way to skin the cat.
Wayne Shaw
Active member
Actions are CNC'd too, but still need to be checked/tweaked, etc. Rflshotr has the right idea. Turn and thread a piece between centers, make a jamb nut, run the Savage nut against the jamb, and face it off.
Boyd Allen
Active member
If the shoulder of the nut can be off, why can't the front of the nut, that a jam nut would bear on?
My interest in originally posting this thread was how to accurately hold the part for a clean up cut.
Some seem to not realize that using a shoulder to jam against or using a jam nut method would only be accurate if the end of the part you’re jamming against is already square to the center line of the threads (assuming we have some thread clearance). The whole assumption in truing up the barrel nut is that it might not be square with thread center line. Indexing the part off the threads alone is the easiest way to assure that the center line of the threads are running true when you take a clean up cut on the shoulder. You could turn a mandrel with a thread fit so snug the part couldn’t twist much but a slightly smaller expanding mandrel with a normal amount of thread clearance would accommodate variations in manufacturing tolerances.
In the middle of another project right now…I’ll post a picture after I make what I have in mind.
Some seem to not realize that using a shoulder to jam against or using a jam nut method would only be accurate if the end of the part you’re jamming against is already square to the center line of the threads (assuming we have some thread clearance). The whole assumption in truing up the barrel nut is that it might not be square with thread center line. Indexing the part off the threads alone is the easiest way to assure that the center line of the threads are running true when you take a clean up cut on the shoulder. You could turn a mandrel with a thread fit so snug the part couldn’t twist much but a slightly smaller expanding mandrel with a normal amount of thread clearance would accommodate variations in manufacturing tolerances.
In the middle of another project right now…I’ll post a picture after I make what I have in mind.
Well I finally got time to machine a mandrel and true up a barrel nut…ended up being easier than I expected. I trued a piece of 6061 then chucked it up in the four jaw. I had expected to thread, drill and tap for a pipe plug and then spilt the threaded portion into four segments so it would expand easily. I had used this approach several times before on other mandrels with good success. While sneaking up on the threaded diameter I realized that with a tight enough fit I might not need the expanding feature. I reasoned that it shouldn’t take that much grip for the light cuts necessary to true things up. I got the thread diameter to where the nut would just screw on with some effort by hand. I still had my ¼” carbide boring bar in one of the tool holders from some previous work. The inserts that this tool uses have very sharp edges so that’s what I used to make two very light cuts which cleaned things up nicely.
Measuring before truing showed TIR 0.0015+, after truing, zero.
This was just one barrel nut, if the next one doesn’t screw on snug enough I’ll go ahead and finish making the mandrel an expanding version.
Before Truing
After Truing
Setup
Cheers,
Bob
Measuring before truing showed TIR 0.0015+, after truing, zero.
This was just one barrel nut, if the next one doesn’t screw on snug enough I’ll go ahead and finish making the mandrel an expanding version.
Before Truing
After Truing
Setup
Cheers,
Bob
pbike
New member
This is a great topic and We've all seen great ways to set up to do this operation, but the question remains, why not just set up the new barrel for a savage with a shoulder, like the Remington and others? This way the headspace is set up correct once and once brass is built and dies are set, each time you put this barrel back on the rifle no problems are encountered.
Paul
Paul
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T
TRA
Guest
FWIW
Tightening a nut or stud, anything threaded, up against the end of the thread causes the alignment of the parts to become skewed .
That's part of the reason all threaded assemblies use a shoulder to register against. Threads were never meant to be a means of precise alignment.
I would venture to say that those nuts are out more, now, than when you started.
To demonstrate what I'm saying, take a bolt and screw the nut down tight and spin it in your lathe and you'll see what I mean. You can probably do it in your hand and see the nut twist when it gets at the end of the threads. There was no common method to verify if it was out of square, nor if it is now.
Even if the nut is "true", it could still skew the barrel when tightened, due to thread tolerances of the 3 parts.
Tightening a nut or stud, anything threaded, up against the end of the thread causes the alignment of the parts to become skewed .
That's part of the reason all threaded assemblies use a shoulder to register against. Threads were never meant to be a means of precise alignment.
I would venture to say that those nuts are out more, now, than when you started.
To demonstrate what I'm saying, take a bolt and screw the nut down tight and spin it in your lathe and you'll see what I mean. You can probably do it in your hand and see the nut twist when it gets at the end of the threads. There was no common method to verify if it was out of square, nor if it is now.
Even if the nut is "true", it could still skew the barrel when tightened, due to thread tolerances of the 3 parts.
TRA,
I think you're making at least one assumption maybe two, I didn't tighten against the end of the thread. I was carefully bringing the thread diameter to size and where I stopped the nut could be screwed on by hand but with some force and would tighten a little more just shy of full thread engagement of the nut, not full engagement of the threads on the mandrel. My guess is that one of the parts has a very slight taper causing the pieces to snug just enough to allow a light cut. The second assumption, that I don't know enough to not run up on the end of a thread.
Cheers,
Bob
I think you're making at least one assumption maybe two, I didn't tighten against the end of the thread. I was carefully bringing the thread diameter to size and where I stopped the nut could be screwed on by hand but with some force and would tighten a little more just shy of full thread engagement of the nut, not full engagement of the threads on the mandrel. My guess is that one of the parts has a very slight taper causing the pieces to snug just enough to allow a light cut. The second assumption, that I don't know enough to not run up on the end of a thread.
Cheers,
Bob