Barrel Nut Truing

[zp3design]

I'm getting ready to face some barrel nuts for my first time and I'm curious what setup others have used to accurately face true to the center line of the threads?

I'm thinking of an expanding threaded mandrel...?

Thanks,
Bob

 

[Preacher]

If I was going to face off one of those Savage barrel nuts I would turn a arbor, thread it and screw the nut on that and cut away....

 

[Robert]

I'm getting ready to face some barrel nuts for my first time and I'm curious what setup others have used to accurately face true to the center line of the threads?

I'm thinking of an expanding threaded mandrel...?

Thanks,
Bob

Bob,

I think a threaded expanding or conical mandrel the only logical method.

R.G.C

 

[Kenny474]

If I was going to face off one of those Savage barrel nuts I would turn a arbor, thread it and screw the nut on that and cut away....

Preacher knows his stuff, I would use his method if it were me.

 

[zp3design]

Thanks for the responses fellas.
Expanding mandrel is where I was headed originally...going to stick with that.

Bob

 

[p17enfeild]

go with pearcher!!!!
how much will it cost to make the expanding mandrel???

 

[Julietvictor]

+1 for the arbor. I have been putting it off myself. I will have to make one soon. If you do it right you can face the action too.

 

[therifler]

is your barrel going to have an expanding thread on it as well?

 

[shortgrass]

go with pearcher!!!!
how much will it cost to make the expanding mandrel???

Nothing but time if you are making it yourself. A simple machining job. If you cann't tackel a job like making the mandrel you probably shouldn't be truing a nut or cutting a chamber.

 

[zp3design]

Fellas,

I had originally posted this at two sites here and at benchrest.com where it drew many responses. I hadn't made a mandrel for this operation at the time and was asking for opinions on the same.

It ended up being pretty quick and easy...trued up a piece of 6061 to thread major diameter, cut threads to a size where nut would just screw on by hand with some effort. Didn't use a shoulder to stop nut or bottom nut on end of threads so all that was aligning nut was threads. Original shoulder was 0015" out of true, took two very light cuts to clean up...break the edges and I was done.

My 4 jaw is pretty accurate and repeatable so I marked the mandrel for jaw no 1 and will check mandrel for running true next time I use it. If the next nut doesn't fit threads I will go ahead and make it an expanding mandrel using the old pipe plug trick.

Thanks for responses,
Bob

 

[treeman]

how can an expanding mandrel stay true to the center line of the lathe? I don't see how it could.
treeman

 

[Marksman]

Once someone gets the process down, I'd be interested in getting my nuts trued.

 

[zp3design]

how can an expanding mandrel stay true to the center line of the lathe? I don't see how it could.

It's not imperative that the center line of a cylindrical part that you want to face or square to 90 degrees be held dead nuts on center but it must be held perpendicular to what ever tool (lathe, mill, surface grinder) is removing the material to make the surface square to the parts center line.

If the mandrel is designed so that the expanding portion is cut into equal quadrants the very slight expansion necessary to hold a part shouldn't move a part that is almost as long as it is wide out of square by much at all.

How about this: machine your mandrel with close fitting threads, then drill and ream a morse taper in the center then split the mandrel. To machine install part and tap in a matching morse taper to expand and hold part.

Still doesn't give the control of a collet closing inside and accurate housing but it might give a bit more accuracy than using a pipe plug to expand the mandrel.

 

[JDJones]

Here is what I do

Chuck up piece of 1.25" stock , turn down and thread leaving a shoulder ensuring that the threaded portion is .125" shorter than the nut length , thread it so that the nut goes on snug (class 3)
thread the nut onto the "mandrel" backwards so that the rear of the nut is facing the outside and face off.

If your lathe is running conventionaly and your not cutting off the back side the nut can't back off or get loose because of the direction of rotation.

you nut is riding on threads that were cut strait so when the nut is run up on them and the back of the nut is faced off it is faced off square to the threads

Its a very easy process

 

[jonbearman]

I lap my savage nuts on a high grade surface plate and screw the barrel in with the nut and blue it up to check contact.I have had great luck with doing it this way.

 

[Samdweezel05]

I lap my savage nuts on a high grade surface plate and screw the barrel in with the nut and blue it up to check contact.I have had great luck with doing it this way.

There is no way I could ever start off a sentence like that. You made soda come out of my nose.

 

[jonbearman]

I am glad I did,LOL