I'm trying to decide who to chamber my new barrel.

The methods that the smiths I have called use are:-

Concentric to the outsideof the barrel diameter (surely not good?)

Drilling a rough chamber with a drill to reduce reamer wear... despite claims of BR accuracy and minute run out, what the hell stops the reamer from wandering off and becoming eccentric from the bore?

Use of reamer from start with pilot to guide with finishing done by hand and T piece.

Starting to get confused. It's not as if this is going to be BR but it's a high quality cut rifle barrel and I don't want it done poorly through lack of knowledge!

A couple people discussed it here the other day, summed up it was:
Chamber and thread concentric to the bore
Rough drill to (approx) .050 undersize/short
With a carbide boreing bar, machine to .010-.005 undersize
Finish with a reamer

https://forums.accuratereloading.com/eve/forums/a/tpc/f/9411043/m/952108124

floating holder...

use a drill or endmill to bore to as close as possible...

finish with reamer

TG, the second bore, with a bar, is a setup and time eater!!

jeffe

Jeffe
Was attempting to condense the thread referanced, not making a recogmendation of methiod.

quote:

Originally posted by jeffeosso:
floating holder...

use a drill or endmill to bore to as close as possible...

finish with reamer

TG, the second bore, with a bar, is a setup and time eater!!

jeffe

Quick change tooling makes the job a breeze even for folks who are in a hurry.

Malm,
take me about 90 seconds to change to a boring bar... but it's NOT in my tailstock...

.040 aint enough, for me, to have a third opprotunity to screw upoperation
jeffe

you really should be negotiating accuracy guarantees with your smith and forget the method.

Ask what accuracy the smith will guarantee...see what he says.

I don't understand why a guy buys a barrel and takes it to the smith to be chambered and fitted. It's like buying a steak and taking it to a fancy steakhouse to be cooked for him.

FWIW I start out by making a piloted center out of brass and (not trusting the center provided on the barrel) make a light OD pass on the barrel so that the OD and bore as as concentric as possible.....well within .0005 IMO

I then use a steady rest on the OD and install my finish reamer (piloted) in the tail stock and ream the entire chamber (lubbing the reamer and blowing chips every .100 of depth of cut). This is hard on the finish reamer but I've never had one wear out but then again I've never cut more than a dozen chambers with any reamer yet.

I'm not claiming this method to be best....it's just my way.....and so far it's worked fine.

I like to dial in both ends of the bore with a 4 jaw chucks on either end of the headstock.

But when the barrel is too short to reach through my headstock, I must use the steady rest.

To get something round and concentric on the outside of the barrel [for the steady rest] is a real trick. I sometimes use pin guages convered in way oil with one end in the tailstock chuck and the other end in the muzzle as a pilot.

quote:

Originally posted by jeffeosso:

.040 aint enough, for me, to have a third opprotunity to screw upoperation
jeffe

Thank God for floating holders...

quote:

Originally posted by malm:

quote:

Originally posted by jeffeosso:

.040 aint enough, for me, to have a third opprotunity to screw upoperation
jeffe

Thank God for floating holders...

I didn't say RUN OUT!!!

quote:

Originally posted by jeffeosso:

quote:

Originally posted by malm:

quote:

Originally posted by jeffeosso:

.040 aint enough, for me, to have a third opprotunity to screw upoperation
jeffe

Thank God for floating holders...

I didn't say RUN OUT!!!

That's reassuring!

One of the smartest and best investments I have made in the last few years was an Aloris quick-change tool post. For any operation where you need to change from one cutting tool to another within the same set up they can’t be beat, especially for us novice machinists.

quote:

Originally posted by Rick 0311:
One of the smartest and best investments I have made in the last few years was an Aloris quick-change tool post.

Without a doubt! That and the Albrecht keyless chuck for the tail stock and mill are real time savers.

To an extent I'm much more concerned abou the dimensions the finish reamer is ground to than in the technique used to cut the chamber, though a response of, "I jus put er in the 3 jaw and letter rip" would tend to give me some trepedation

I'm thinking most smiths zero the bore on both ends of the headstock with a 4 jaw and spider, and then use a floating pilot reamer floating holder and dial indicator to cut to depth.

I have built match grade rifle for over 35 years, I hope I have it right.

The first thing I do is cut off the first 3/8" from the breach end using a band saw.
Next, chuck up the breach end in the chuck and face it off.
Next, chuck the muzzle end in the chuck and the breach in the tail stock center.
Next, very lightly turn the barrel down until it will clean up completely.
Next, turn the shank to size for threading.
Next, thread it.
Next, keep working on it till its done.

Please excuse me if this is a dumb question, I am NOT a machinist.
One of our local smiths chambers and threads from the same setup with the chamber end in the 4 Jaw chuck and the muzzle sticking out through the left side of the lathe. He said that he uses a piloted reamer and it will follow the hole in the barrel. Are there any advantages/disadvantages to his system?............DJ

The tail stock will NEVER line up perfectly with the spindle hole. No matter how well you think you are doing with this method the base of the chamber will always be oversize compared to the reamer. I call that the "short cut method"

quote:

Originally posted by DFC:
The tail stock will NEVER line up perfectly with the spindle hole. No matter how well you think you are doing with this method the base of the chamber will always be oversize compared to the reamer. I call that the "short cut method"

The tailstock damn well better line up with the spindle hole. If it won't, sell the machine.

quote:

Originally posted by DFC:
The tail stock will NEVER line up perfectly with the spindle hole. No matter how well you think you are doing with this method the base of the chamber will always be oversize compared to the reamer. I call that the "short cut method"

One of the main advantages to the quick change tool posts is that you can run the reamer, mounted in a floating holder, from the carriage table/tool post rather than from the tail stock, and you can align it perfectly with the set up that DJ mentioned. Using the same, perfectly aligned set up, your can swap between 60 degree center drill bit, twist drill bit, boring bar, reamer...whatever, without disturbing that alignment.

Rick, I think that's how they do it. There is only about 2" or so of the barrel sticking out from the chuck. Just enough to cut the threads. I don't think the tailstock could get close enough with the tool post? in the way..........DJ

Malm, gotta love ya....

Use a drill to get most of the meat out but then for goodness sakes, take a truing cut with a small boring bar... Then, and only then, is the drilled hole round AND concentric to the bore... Given the bore was properly indicated in.

I'll just put my .02 in here. I indicate both ends of the barrel, using a 4-jaw on the chamber end and a "spider" I made for the opposite end of the headstock. I rigged up a mount for a dial indicator that is bolted to the gear cover to indicate the muzzle end of the bore. Once I get both ends dialed in I ream the chamber using another dial indicator I mouted on the tailstock measuring depth. I pre-drill the chamber using a twist drill as close to the chamber size as I have. I don't think using a boring bar would add anything but time to the job.

dj, that is the way that I chamber and as far as I am concerned it is the only way to do it. As DFC says the tailstock will more than likely be off a bit, but I wonder how he holds his reamer when chambering. He is saying use the tailstock that isn't true to turn the O.D. of the barrel, plus who is to say that the center is running true. I have always used the headstock with a buck adjust tru chuck to indicate the bore with a .0001 indicator. Indicate the muzzle end in a home made spider with the same indicator. Turn the barrel tenon and thread. Chamber with a floating holder [only one that I have found to be worth a damn is J.G.S.]. Make sure that you get your measurement across a set of wires from a known barrel and you are set to go. It makes it a lot easier to indicate the bore if you have a full set of pilots and indicate off the proper size, a lot easier than trying to indicate off the lands or grooves. I have used my barrels in quite a few I.B.S. score matches and won probebly more than my share.

quote:

Originally posted by djpaintles:
Rick, I think that's how they do it. There is only about 2" or so of the barrel sticking out from the chuck. Just enough to cut the threads. I don't think the tailstock could get close enough with the tool post? in the way..........DJ

You can align the cutting tool of your choice dead on the money using that method once you have the barrel indexed off the bore.

Mark Stratton has great photos and text describing this in his book.

I’m nothing more than a self taught garage “machinist†and if I can get straight chambers using this method I would assume that just about anyone could.

Rick, how do you get the reamer or other tool set dead nut in both axies with it in the cross feed? I have tried this on barrel stubs and always felt better about the tail stock and a floating holder, I realize that some of them suck but the J.G.S. is a very good one. If you can cut a foot or longer piece of stock with no taper to it, the tailstock can not be far off. I grant you it can be a bitch getting it set up originally, but I think it pays off.

quote:

Originally posted by b beyer:
Rick, how do you get the reamer or other tool set dead nut in both axies with it in the cross feed? I have tried this on barrel stubs and always felt better about the tail stock and a floating holder, I realize that some of them suck but the J.G.S. is a very good one. If you can cut a foot or longer piece of stock with no taper to it, the tailstock can not be far off. I grant you it can be a bitch getting it set up originally, but I think it pays off.

I use a Dave Manson floating holder mounted in an Aloris â…†boring bar tool post. The Aloris tool posts are adjustable up and down, and the cross feed table is obviously adjustable side to side. Coupled with the floating holder and interchangable bushing piloted cutting tools, I don’t see how you couldn’t be able to get things lined up dead-nuts.

The other advantage to using the cross feed is that it seems to be faster at inserting and removing the reamer for cleaning/lubing than is the tail stock ram.

I just finished up a little experimental scope/ laser tool I’ve been playing with and I bored and chambered 150 pieces of one inch 60161 T6 Aluminum round stock using this method and it sure worked well for me. If anything is crooked the laser beam lets you know real quick when it shoots down the bore. Instead of getting a red dot, you get either no dot at all or a partial dot with halo’s around it.

Oh, the other thing you have to figure is that when turning on centers the tail stock ram is stationary and you can draw it all the way back in so there is no “wobbleâ€. When reaming it is extending and any play in the ram will effect the straightness of your cut unless your floating holder can compensate for it.

I wonder how many folks take a good .0001 Interapid and check the finished chamber for runout ??? I bet some would be dissapointed.

Rick, you are saying that you can line your tooling up dead nut, you sound like you are doing it by eye with no actual method of making sure that it is really on. At least with the tailstock I can attach an indicator to the chuck with a magnetic holder ans indicate off of a dead center in the tailstock and get it VERY VERY close, that with cutting a piece of stock that has no taper as a chech on the tailstock, I think that I will continue with what I am doing. If you had a way of varifying that the reamer was truly on [and there must be a way] I might agree with you. Along with a up and down axis the reamer must also be perfectly parallel with the bore in order to cut a true chamber. I make a cast of every one of the chambers that I cut and all seem to be right on as far as I can see. I agree with you on the Aloris tool posts I bought 3 different size sets at an auction of a shoe plant in Mass. and they are very nice. [got the 3 sets and a half doz. holders each for 75 bucks]

quote:

As DFC says the tailstock will more than likely be off a bit, but I wonder how he holds his reamer when chambering. He is saying use the tailstock that isn't true to turn the O.D. of the barrel, plus who is to say that the center is running true

I have found on most machines the tail stock center will always be higher or lower than the headstock center. The only way to know is put a dead center in both and take a look.
I have a floating reamer holder and it works well.

quote:

Originally posted by b beyer:
Rick, you are saying that you can line your tooling up dead nut, you sound like you are doing it by eye with no actual method of making sure that it is really on. At least with the tailstock I can attach an indicator to the chuck with a magnetic holder ans indicate off of a dead center in the tailstock and get it VERY VERY close, that with cutting a piece of stock that has no taper as a chech on the tailstock, I think that I will continue with what I am doing. If you had a way of varifying that the reamer was truly on [and there must be a way] I might agree with you. Along with a up and down axis the reamer must also be perfectly parallel with the bore in order to cut a true chamber. I make a cast of every one of the chambers that I cut and all seem to be right on as far as I can see. I agree with you on the Aloris tool posts I bought 3 different size sets at an auction of a shoe plant in Mass. and they are very nice. [got the 3 sets and a half doz. holders each for 75 bucks]

Just cuz I said I was an amateur, self taught “garage†machinist doesn’t mean I eye-ball my set ups! I was just trying to say what I used, not trying to write a technical manual on the subject.

I am not claiming to have invented this technique...it was recommended to me by professionals who do allot of precision barrel work.

Use whatever works best for you...this works great for me and I will stick with it until someone shows me something better.

DfC
Read Beyer's post, right before your last, you can put an indicator on the chuck jaws, bring your tailstock within reach, and sweep the interior of the taper of the tailstock.. Then you can sweep a dead center that is in the tailstock. This will give you a hell of a lot better results than eyeballing a pair of center points...

Rick, didn't mean to say anything to upset you, I was just curious as to weather you had a method to line up the reamer in the toolholder with the bore of the barrel. As I said I imagine there is a way, and I would like to know it. I am an amature myself, retired from Verizon after 40 years. Sorry if I said something that rubbed you the wrong way.
DFC, you can always grind or shim the tailstock ways to get it the right height.

quote:

Originally posted by Pat B.:
I wonder how many folks take a good .0001 Interapid and check the finished chamber for runout ??? I bet some would be dissapointed.

I have on many occasions checked the runout of a chamber and the needle remains on zero. I don't now use, or, never have used, a floating reamer holder, and I guess I just don't understand the need for one if the chuck, bore and tailstock are aligned. I don't find fault with those who choose to use them, I just never seen the need.

I use a live center and tail stock to feed the reamer. I attach a lathe dog to the shaft of the reamer to keep the reamer from spinning. I actually use to hold on to the lathe dog with my left hand while advancing the reamer with my right so that I could feel how things were progressing, but that got old real fast. Now I let the leg of the lathe dog ride along the compound rest as I advance the reamer with the hand wheel. I still keep my hand on the lathe dog, but I've long ceased trying to keep it from turning. The above technique is simple but it requires that certain pieces of the machine be aligned. It doesn't take much to check and maintain tail stock alignment. The lathe is a precision machine tool and is designed to be adjusted. Using the above method, if I've done my part, the finished chamber will be centered, concentric and no larger than the reamer.

quote:

Originally posted by b beyer:
Rick, didn't mean to say anything to upset you, I was just curious as to weather you had a method to line up the reamer in the toolholder with the bore of the barrel. As I said I imagine there is a way, and I would like to know it. I am an amature myself, retired from Verizon after 40 years. Sorry if I said something that rubbed you the wrong way.
DFC, you can always grind or shim the tailstock ways to get it the right height.

Bob, if I was upset I wouldn’t have stuck in a happy-face. I don’t rile all that easy, so don’t worry about saying anything that rubs me one way or the other.

My only point is that whatever system of indicating and aligning you choose to use it is much quicker and easier (for me anyway) to line up the cutting tool when it is mounted to the cross feed table and a vertically adjustable holder than when it is mounted in the tail stock that only adjusts left and right.

Once I have the workpiece turning concentric to the bore using dial indicators and a range rod, I can stick a range rod in a 5C collet in my tool holder and insert it right into the bore and I then know that the tool holder is in alignment with the bore and that any cutting tool I put in the holder will also be in alignment with the bore. Is this the best or only way... I have no idea!

Malm, well done.

And yes, I know there are servals ways to go about chambering. Some give fine results, some don't..

quote:

Originally posted by Pat B.:
I know there are servals ways to go about chambering. Some give fine results, some don't..

Don't I know it. Why, if I had a dollar for every "out of whack" barrel and chamber that has come into this shop... Hey wait a minute, I did get a dollar. Never mind!

Some of the worst chambers that I have ever seen come out of the shops of so called pros. One imparticular was so screwed up that the fired case had to be indexed to get it back in the chamber. Another that had so much chatter in it that it was transferred to the case when fired. There are a lot of excellent gunsmiths out there but there are also a lot of real hacks.

The method they taught us at Trinidad: cut off each end of the barrel with the bandsaw and face to the "true" bore. Then mount between centers and take a light skim cut on each end to true that area to the bore. This is of course after the tailstock is checked for alignment using the indicator on the spindle and running it around the tailstock ram and the live center. Also the headstock center is checked and if not running true then a renewable center is cut in the three jaw. The barrel shank is turned to the proper o.d. and then threaded. The trued portion of the muzzle is then dialed in the 4 jaw and the steady rest mounted onto the cylinder. The bore is then checked for runout and adjusted if necessary in relationship to the tailstock. The bore is now pointed at the tailstock center. The chamber is then reamed with the tailstock center supporting the reamer which is held by hand with a lathe dog. They want us to feel the reamer cutting so that we can let go in case of rolling a chip or some other calamity.

The advantage to this set up as explained to us by our instructor, is that by aligning the tailstock and the bore at the far end of the lathe rather than right up at the headstock, then any slight misalignment between the headstock and tailstock is minimized. We also are taught the headstock and Aloris tool post method and are allowed to choose the method that makes the most sense to us after we have a few chamber jobs under our belts.

I suppose it really doesn't matter which method a fellow uses as long as concentricity is strived for and no assumptions are made as to the accuracy of the setup.

Brian Bingham