Chambering in the steady rest new idea I am going to try

My new lathe is longer through the headstock (about 32") so I am chambering between centers. I don't know if anyone has tried this but here is my plan.

The spider I made on my lathe I turned the id and od.

1. center drill muzzle with piloted reamer and turn od for 3/4" or so concentric with bore.
2. With spider mounted in lathe as if I was doing a receiver install the barrel in it with the chamber end out enough to cut tennon. Place steady rest on spider. Center the barrel using Gordy range rod.
3. Release the spider from the 4 jaw. slide the steady rest with the spider and barrel down so that I can clamp the muzzle end up in the 4 jaw with copper wire holding it
4. Indicate again with rod in chamber end adjusting only the 4 jaw holding the muzzle. Mark high spot on muzzle. Do not adjust spider jacking bolts as they should be set from when it was mounted in the 4 jaw. Note the muzzle may not be centered so there would not be any stress on the barrel.
5. Cut tennon and chamber.

In theory this should get the throat, chamber and tennon all aligned. When this is done flip the whole thing around to do the muzzle the same way (crown and/or thread)

The problems I see.
1. I don't know how to set up my flush system this way. I thought about tapping the end of the barrel and running a pipe to the outside of my headstock where I can attach the flushing bearing.
2. Time consuming and a complicated.

Another option I am considering is creating a long spider with heavy wall pipe and support it on the end in the steady rest
1. I can then create jacking bolts every few inches to support any length barrel.
2. I would not have a way to indicate the muzzle end in this setup to find the high spot.

I really would prefer to be able to use through the barrel flushing with my carbide reamers. Any ideas are greatly appreciated. Thanks in advance.

You are turning the simplest way of doing this into a hocus pocus marathon. Try reading this thread:
http://www.practicalmachinist.com/vb/gunsmithing/chamber-reaming-between-centres-230343/

You might search for other posts by Speerchucker as he has it down pat. There is no indicating, range rods. or other hocus pocus. The reamer IS the tailstock center. The steady catches the barrel when you pull the reamer out, nothing else. The pilot has no option but to follow the bore. He has many other very good posts. Certain assholes here annoyed him until he left. I think he can be found at The Home Gunsmith. He has done this for a living for 35 years so is the real deal, not a home shop hack.

I prefer to work in the spindle, and have to with long barrels because I don't have the center distance. When I was using a long spindle Monarch I made a center to go in the spindle that I could dial in at both ends. With my Graziano, and a short barrel, I have a center that slides in a collar threaded on the tail end of the spindle.

Does it run true to 2 tenths? No. Two thousandths? Piece of cake. And with a 20" barrel that translates to 2 tenths over the 2" length of a chamber. And 30 millionths over the width of the bore for crowning. Seems good enough to me.

Tried real hard to talk myself into aligning with the bore at the chamber end and letting the muzzle wander like you're doing. Couldn't come up with any good reason to bother based on the math, and the added complexity of timing the bore offset to the receiver.

As for the tube running in a steady rest, I talked with a guy awhile back about this as a way of setting up to prebore a chamber on a lathe with a spindle bore too small to fit the barrel thru. The more I thought about it the more I liked it. But there's still the issue of dialing in the muzzle end inside the tube. You might have to get a bit creative about accommodating different barrel lengths with a sliding center, or changing the length of the tube.

Another thought was to measure from the OD of the tube to the barrel with a depth Mic' thru extra holes. Or set up a dial indicator with enough travel to clear the tube OD as you rotate it. Could even indicate off a pin in the bore this way.

wesg said:

As for the tube running in a steady rest, I talked with a guy awhile back about this as a way of setting up to prebore a chamber on a lathe with a spindle bore too small to fit the barrel thru. The more I thought about it the more I liked it. But there's still the issue of dialing in the muzzle end inside the tube. You might have to get a bit creative about accommodating different barrel lengths with a sliding center, or changing the length of the tube.

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I don't know how I'd accommodate different length barrels but I was thinking more and more about the muzzle end and I think what would work is using a center in the headstock. If you made a brass one you could make it really shallow so that it's not taking up bed space. The spider at the end of the tube would have to be set against the tenon shoulder because it would need to keep the barrel from moving in the Z.

You don't need to worry about the muzzle end. How much could the concentricity be out? Hold the muzzle in a collet. Now you have a barrel length noodle that has no choice but to align with the pilot. It will probably droop more in the center than the run out at the muzzle. A rifle is a very simple machine and what happens at the chamber end is insignificant compared to the last few inches of rifling.

milotrain said:

I don't know how I'd accommodate different length barrels but I was thinking more and more about the muzzle end and I think what would work is using a center in the headstock. If you made a brass one you could make it really shallow so that it's not taking up bed space. The spider at the end of the tube would have to be set against the tenon shoulder because it would need to keep the barrel from moving in the Z.

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I've forgotten the details already, but you can go up to 3/4" in a collet? And what was the spindle bore diameter and inside of the drawtube?

Thinking a piece of 3/4" drill rod, or precision ground 'something' (4140?) with a point at one end. Held in the collet, with a guide bushing at the tail end of the drawtube to hold it centered and prevent whipping. Center distance for different length barrels is set by sliding it to where it needs to be and tightening the collet.

The center is your thrust stop for chambering. Shouldn't be much there anyway, as I've never seen a barrel move with nothing but 4 set screws at each end. In fact, with the setup I had in the big Monarch, the barrel would get loose a bit and rattle on the center as the spindle warmed up. If it was moving in the 4-jaw with a copper wire, or fancy split aluminum sleeve, on the OD, it sure wasn't being pushed back.

I think the collar at the end of the tube should be a pretty stout chunk of steel. As big as you can get in your steady rest, within reason. With a couple of 'thin' wall sleeves I've used, I can see them distorting out of round as the screws are tightened. If you need any help turning up a piece like that let me know.

As for TD's comment, this isn't necessarily about what he 'should' do, or what he 'needs' to do, it's about what he 'wants' to do. I don't see anything fundamentally wrong with Spearchucker's method. It works for him and I'm sure it would work for any of the rest of us too.

But there are some things you can't do with it. Like preboring to rechamber a 6.5-06 to a .264 like came up in a recent post. No way to get the thing to run on the pilot until it's too late. Can't fix a crooked chamber by setting the barrel back either, unless you can cut all of it off.

As a side note, just to brag a bit, I did a .308 recently. In the spindle, prebored of course. Chamber runout was for all practical purposes zero. And this was a Palma reamer with a .298 pilot, in a standard bore barrel that would take a .3005 gauge pin. And I used my knurled aluminum collar on the reamer, held by hand, with nothing supporting the tail end of the reamer. Probably a damn good thing it was too long to do between centers ;-)

wesg said:

I've forgotten the details already, but you can go up to 3/4" in a collet? And what was the spindle bore diameter and inside of the drawtube?

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Spindle bore is 25/32", but the spindle nose is a 3MT and I did find a 3/4" 3MT collet, so I figured that I'd get a more bed by shoving the barrel tenon into the 3/4 collet.

wesg said:

Thinking a piece of 3/4" drill rod, or precision ground 'something' (4140?) with a point at one end. Held in the collet, with a guide bushing at the tail end of the drawtube to hold it centered and prevent whipping. Center distance for different length barrels is set by sliding it to where it needs to be and tightening the collet.

The center is your thrust stop for chambering. Shouldn't be much there anyway, as I've never seen a barrel move with nothing but 4 set screws at each end. In fact, with the setup I had in the big Monarch, the barrel would get loose a bit and rattle on the center as the spindle warmed up. If it was moving in the 4-jaw with a copper wire, or fancy split aluminum sleeve, on the OD, it sure wasn't being pushed back.

I think the collar at the end of the tube should be a pretty stout chunk of steel. As big as you can get in your steady rest, within reason. With a couple of 'thin' wall sleeves I've used, I can see them distorting out of round as the screws are tightened. If you need any help turning up a piece like that let me know.

As for TD's comment, this isn't necessarily about what he 'should' do, or what he 'needs' to do, it's about what he 'wants' to do. I don't see anything fundamentally wrong with Spearchucker's method. It works for him and I'm sure it would work for any of the rest of us too.

But there are some things you can't do with it. Like preboring to rechamber a 6.5-06 to a .264 like came up in a recent post. No way to get the thing to run on the pilot until it's too late. Can't fix a crooked chamber by setting the barrel back either, unless you can cut all of it off.

As a side note, just to brag a bit, I did a .308 recently. In the spindle, prebored of course. Chamber runout was for all practical purposes zero. And this was a Palma reamer with a .298 pilot, in a standard bore barrel that would take a .3005 gauge pin. And I used my knurled aluminum collar on the reamer, held by hand, with nothing supporting the tail end of the reamer. Probably a damn good thing it was too long to do between centers ;-)

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I think that would work with an adjustable spindle center but at this point I don't see myself working on a pile of different length barrels. I do have a nice big 2-3/4" timken bearing in a pillow block that I might setup as a four screw steady if need be. For now thought I'm going to take one of these older toast barrels, stick it in the steady and pre-drill it. Just going to see how "off" that method is (maybe not much at all).

Thread is timely, as I'm an 07 FFL, just completed the rebuild on the new-to-me South Bend that has a small spindle bore and was looking at methods other than what seems to be the "preferred" one of thru-the headstock.

I'm attaching a video from a smith that had (retired professionally since) a tremendous reputation on one of the premier precision rifle forums. His method, is similar to one I was reading up on by Steve Acker.


Mr. Suarez submits that working with the steady is no less accurate than working through the headstock (as does speerchucker in the linked thread above). As far as a Grizzly/indicating rod to indicate the bore- his argument that it is unneeded is logical to me. A floating reamer holder will allow the reamer to align itself to the bore, making a few thousandths TIR irrelevant. Acker also uses the 60 degree chambered pilot to cut centers- and I found it interesting that Suarez uses a dead center with lube in the tailstock- which I too will do. Eliminates any runout of a live center (and good ones are $$$$$$)- and given the low rpm and limited time the barrel spends on it makes sense to me.

One thing that Acker does in addition, is after the trueing cut is made on the barrel end- he drills a holes completely through and inserts a roll pin, biased against one of the chuck jaws to eliminate any possibility of the barrel spinning in the chuck. Obviously, this goes away when the barrel is cut/crowned.

Like I said- I'm learning as well- so comments/feedback are appreciated.

He uses the dead center to eliminate the error of the runout of a live center, then goes to setup the steady rest with the (precision roller bearings) and thinks there is no runout in the steady rest bearings. He's even using high quality Brownells chambering oil.

Popcorn time!

I am going to build a dead center with through coolant capability for the chamber flush system like was done above So that I can flash with lubricant while reaming. My thought on the complicated setup was to align the bore and throat up.

I also prefer to have my muzzle timed so that if there is any deflection it is aimed to the top. This way shot variance is vertical. With this method my windage should be centered.

I believe the 2 most important parts of the barrel are the chamber/throat and the muzzle/ last 2 inches or so. That is my reason for trying something like I came up with above.

paracongo308 said:

He uses the dead center to eliminate the error of the runout of a live center, then goes to setup the steady rest with the (precision roller bearings) and thinks there is no runout in the steady rest bearings. He's even using high quality Brownells chambering oil.

Click to expand...

Point is taken- but what's the TIR on the roller bearings? And as he states in the beginning, there comes a point when the inconsistency in machining likely can't be distinguished from that of the barrel. Where that lies is what I'm trying to figure out. Like I said, I checked out the smith, do a search on him at the Hide. His rifles back up his rhetoric.

Vid didn't show him chambering with the Do-Drill (just cutting the centers). Mebbe the Viper's Venom was offscreen...

C'mon Holescreek- seen your work at the Files. You don't just wanna sit back and get fat on popcorn, do ya?

cgmaster said:

I am going to build a dead center with through coolant capability for the chamber flush system like was done above So that I can flash with lubricant while reaming. My thought on the complicated setup was to align the bore and throat up.

I also prefer to have my muzzle timed so that if there is any deflection it is aimed to the top. This way shot variance is vertical. With this method my windage should be centered.

I believe the 2 most important parts of the barrel are the chamber/throat and the muzzle/ last 2 inches or so. That is my reason for trying something like I came up with above.

Click to expand...

Though I fully support "clocking", I wonder how "shot variance is vertical" can be controlled with the presence of barrel distortion and animation during the shot cycle.

Sometimes empirical process are sufficient to accommodate good intention.

C'mon Holescreek- seen your work at the Files. You don't just wanna sit back and get fat on popcorn, do ya?

Click to expand...

I post on a lot of gun boards and have been a member here for a long time. One thing I've learned, especially in the last two years, is that few here can agree on anything and everybody likes to fight. Nothing brings it out faster than topics involving chambering.

My suggestion is that you search for all the old barrel chambering threads here you can find, read them, then forget that video (or at least parts of it).

Hmm, cleaning up the center by rotating the reamer with the barrel stationary. I believe that to be flat out wrong.

wesg said:

Hmm, cleaning up the center by rotating the reamer with the barrel stationary. I believe that to be flat out wrong.

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Can you explain why?

This novice doesn't understand why a tightly-piloted, true 60-degree form tool like this one from PTG, can't be used to cut a very accurate center concentric to the bore. Is it because the pilot itself is not long enough (as an indicating rod would be) to accurately center?

60


Holescreek: Thanks,will do.

New to machining, but a lifetime as a contractor in the trades and know there are often many roadmaps to the desired end result (and 1,000 yard shooting is our hobby). To me, if there is one method that is more "correct" than another, it needs to be manifested at the target- not just theory. And at a point, it becomes irrelevant if the result is that 99.9% of the shooters driving the rifle can't tell the difference.

Holescreek said:

I post on a lot of gun boards and have been a member here for a long time. One thing I've learned, especially in the last two years, is that few here can agree on anything and everybody likes to fight. Nothing brings it out faster than topics involving chambering.

My suggestion is that you search for all the old barrel chambering threads here you can find, read them, then forget that video (or at least parts of it).

Click to expand...

Agree. I think that the 'discussion' of the different ways to go about chambering is good food for thought for a novice. It should lead to a better understanding of how to use your lathe and equipment for your own purposes.
But once you have done the best job with what you have, there is no garantee that the rifle will shoot. Top competitors will replace a 'bad' barrel with a new one that has been machined in exactly the same way. In my case the machining I do has to be good enough so that it can be confidently eliminated as a possible cause of inaccuracy of the rifle. There is no magical chambering technique that will win you matches or a clean kill. [/I]

tobnpr said:

Can you explain why?

This novice doesn't understand why a tightly-piloted, true 60-degree form tool like this one from PTG, can't be used to cut a very accurate center concentric to the bore. Is it because the pilot itself is not long enough (as an indicating rod would be) to accurately center?

Click to expand...

Mainly stirring the pot, but ...

If the tailstock isn't centered the reamer will cut off center. Driving the barrel 'should' average that out. That assumes it's running true at the other end. Even if not, it's so much longer than the reamer that the angular error is much smaller.

Running the reamer, or a grinding stone, is how they true centers in parts for cylindrical grinding. But they support the other end on a center, not on the OD in a chuck. I've trued centers in a similar way, with the reamer in the spindle and a center in the tailstock. Still the issue of alignment, but it's over the length of the barrel this way.

If the pilot is good enough, why bother with the lathe at all? Again, just complicating the setup and wasting time for little to no gain.

And be careful with 'tight' pilots. A lot of these barrels are flared a bit at the ends from lapping. So what you think is a good fit at the end becomes too tight as you go deeper. I've seen them burnish the tops of the lands. Don't know that it did any real damage, but it's not something you want to see through a bore scope.

If you've never done a barrel before, I think you're wasting your time trying to figure out the 'best' method. I probably used 6 different methods on my first 4 barrels. And another 3 or 4 different ones after that.

First was an AR barrel in a Monarch EE. Barely fits between centers to begin with. How are you gonna chamber that? Simple, you turn the front sight base journal and hold it in a collet, and support the other end in the steady rest. And then you find out the only steady rest we have is for the older EE and the center height isn't the same. So I'll have to use the older one, but it won't cut a decent thread, so ...

In the spindle is sooooooo much easier.

Wesg,

Understood, thanks. Makes sense.

I'll add that Acker in the book I mentioned above does submit to exactly your point. He uses the 60 degree center- but does also say he prefers using the indicator rod. Most barrel manuf's do recommend cutting an inch off the muzzle end as you say; if length allows perhaps it would be a good idea to do it at the beginning (if a piloted center were to be used), then another cut-off later to remove the trueing cut/shoulder before crowning.

As I said, self-teaching- and with some mentoring by a lifetime smith down the street who's forgotten more than I'll ever learn and is helping me now with the work I get in prior to me deciding I'm ready to fly "solo".

Having an FFL sure doesn't make me a gunsmith... and damn if I'm going to screw up someone's gun out of the gate (I'm sure it will happen eventually, though!) As you say, I know trial and error is all part of the process. Just gathering input so I can begin making mistakes and learning from them.