Hi All,

I want to put together a couple of wildcats using Martini actions; I have all the parts, and a lathe, a mill, stocks etc. I have been learning to use the lathe, turning, threading, boring and contouring. I plan to use the 5.6x50R parent cartridge necked up to 6mm to form a 6x50R with a 32-degree shoulder. I have two Remington “varmint†contour 6mm take-off barrels, I’ve turned the barrels to .950†at the breech, I’ve cut the chamber section off and cut the shank to the major diameter ready to thread.

Now I have some (a lot) questions about the chambering, I would like to have some suggestions on the reamer holder to use and I am looking at the 6mm hole in the barrel and thinking that the reamer is going to have to remove a lot of steel, should I “pre-bore†the chamber? If so how is the pre-bore done? What about the cutting speed, I’ve heard everything from 60RPM to 300RPM, since I do not have a “through the bore†coolant system I guess I should keep it slow?

Any and all help, comments, suggestions are welcome and really appreciated, I hope to occupy my retirement years working on my gun projects and I’m learning as of now.

Thanks

Marcos (elalto)

You know Marcos, I'm in the very same situation (except that I'm hoping to occupy my new-found free time since finishing school and just dealing with my 9-5).

I was all set to buy a floating reamer holder on EBay when I came across this article on Mike Bryant's website: http://www.bryantcustom.com/articles/rebarrel.htm I think you'll agree that the simple tool he employs would be very straightforward and makable for you and I with our comparable comfort level/experience with our machines. There's great information regarding other chambering issues in the article as well.

My rookie barrel, by the way, is a 6mmbr for a special Ruger #3, so it looks like I'll get to use the mill to make that extractor cut... I swear I get a lesson every time I step into that garage (the sign of a neat hobby)!

many years ago I actually clamped a chambering reamer in a vice grip, turned the barrel in the lathe with a steady rest at slowest RPMs (about 100) and hand chambered the thing holding the reamer and vicegrip in my hands. It worked and worked fine.....

This I still do today...
rpm to be about 60-150 .....slow to avoid chatter.

HSS piloted reamer....I cut so few chambers that I cut the entire chamber with the reamer. I've never predrilled the chamber or roughed it. This has worked for me. My .25-06 reamer has now cut over a dozen chambers this way and is still fine.

Use lots of cutting oil and blow the chips out of the barrel often....at least every .100 depth of cut.

Today I make a centered pilot for the bore and turn a small amount on the barrel shank concentric to the bore. I then prepare a steady rest about that diameter and chamber from the tail stock.

There's probably better ways but this has done the trick for me.

Hey,

I envy you guys. What kind of lathes are you using? I've been looking at bench lathes from Enco, Grizzly, Wholesale Tool, Harbor Freight, etc.

On speeds for chambering, some smart folks addressed that in this thread:

https://forums.accuratereloading.com/eve/forums/a/tp.../240104823#240104823

I believe they suggested 60 or 70 rpms.

Steve

quote:

What kind of lathes are you using?

Mine is a Jet 13" X 40 bed with 1.5 hole thru

It's a cheapie I guess but for about $3,000 it does all i want except metric threads.

That's no cheapie... mine's a cheapie :-)

A 1952 Logan 11"X36" w/ a 1.375" through hole. It cost an even $1000, but it came with plenty of original tooling and looks like it just came out of the plant in Chicago. Probably the minimum size for hobby gunsmithing or under that in some folks eyes but it was a wedding present from my new wife and I think it'll do just fine.

What ever you do KEEP THAT WIFE.
Good Luck!

Elalto,
I use a JGS floating reamer holder on a boring bar attachment with the quick change tool holder on the compound. The ones sold on ebay are junk. The compound allows you to remove the reamer quickly and clean it much faster and ultimately more often that using the tail stock.

I don't chamber often, I learned this from someone who does. Brilliant suggestions don't generate in my head, I just pass them on.

quote:

Originally posted by vapodog:
many years ago I actually clamped a chambering reamer in a vice grip, turned the barrel in the lathe with a steady rest at slowest RPMs (about 100) and hand chambered the thing holding the reamer and vicegrip in my hands. It worked and worked fine.....

This I still do today...
rpm to be about 60-150 .....slow to avoid chatter.

HSS piloted reamer....I cut so few chambers that I cut the entire chamber with the reamer. I've never predrilled the chamber or roughed it. This has worked for me. My .25-06 reamer has now cut over a dozen chambers this way and is still fine.

Use lots of cutting oil and blow the chips out of the barrel often....at least every .100 depth of cut.

Today I make a centered pilot for the bore and turn a small amount on the barrel shank concentric to the bore. I then prepare a steady rest about that diameter and chamber from the tail stock.

There's probably better ways but this has done the trick for me.

vapodog,

Are you doing this totally hand-held or are you also supporting the reamer with a center in the tail stock?

years ago I actually did it totally hand held.....and with success on even .375 H&H size reamers.

I do it totally by machine today by carefully aligning the rifle bore to the steady rest and that to the tail stock. I then chuck the reamer in the yail stock chuck and control the reamer feed with the tail stock wheel.

I have also done a combination of these such as:

Notice the reamer has a square ground on the end. If you align the bore with the steady rest and then to the dead center in the tail stock and then hold the reamer between piloting in the bore and the dead center and using a small wrench to prevent rotation of the reamer you can feed it via center from the tail stock. Now you're actually causing the rotation resistance by the wrench on the reamer.

All of these methods have worked for me but the one I like the best is the one actually chucking the reamer in the tail stock chuck.

Use lots of cutting oil and feed slowly and clean the bore and reamer at least every .10 of feed.

One more thing. I like to chamber about .005 too deep and then after I measure the headspace I adjust it same as one would do a long chambered barrel. It's easier to control the depth to .001 facing the end of the barrel then it is to control the reamer depth.

I guess I shouldn't answer a question with a question, but here goes anyway...

Are you going to chamber with the barrel in the headstock, or in a steady-rest?

If you are doing it in the headstock, I think it pays to make yourself a "Spyder" so you can center the bore on both ends of the headstock. (one end of the bore is centered in the 4-jaw chuck, and the other end of the bore is centered in the "spyder".

Then, I also use a "range rod" to center the work "set-up" on the exact center of the bore...rather than on the outside of the barrel blank. (Outsides aren't always perfectly round, and bores aren't always in the exact centers of the blanks.) The "range rod" is a specially tapered rod...obtainable from commercial reamer makers. You put the rod in the bore, then set your dial indicator to bear on the portion of the rod protruding from the bore, and center from those indicator readings. (Just like with any other centering operations with long slender stock, it pays to center both ends of the barrel alternately several times before cutting a shank, threads, or the chamber, to get it really, truly, centered.)

Next. I personally prefer to use only "floating pilot" reamers, and I make my own pilots to within .0002" of the actual bore size (land diameter) of the specific individual barrel to be chambered. (Commercial barrels may vary up to .001" or even more in actual interior diameter from one barrel to another. Even though they each may be uniform to .0001" over the length of the bore, the actual diameter from which they do not vary may be considerably different from barrel to barrel, even when made by the same maker on the same day.)

When I chamber with a barrel through the headstock, I use a JGS floating reamer holder. This fixture allows the reamer to self-center as the pilot follows the bore, and the reamer holder compensates for any misalignment of the tailstock center (or reamer butt end) to both the headstock and the center of the barrel bore, up to .004". Of course, one never wants any such misalignment, but insomuch as barrel bores ofen are not perfectly straight, it can occur without your knowledge as the chamber deepens.

Of course, perfectly useable chambers can be cut and barrels fitted without the use of a floating reamer holder, a floating pilot, a range rod, or even a Spyder. It's just that if I am going to spend $300 to buy a high quality barrel blank and use my time to chamber & fit it to a fine action, I figger I might as well make everything as precise as I know how....

I have actually seen a production shop chamber barrels. This shop actually bores the chamber.they do not ream it.

I asked about concentricity of chamber to bore and was told that their tests showed that as long as the chamber was concentric to the rifle bore w/n .001 TIR all was fine and that they had no trouble doing that. Accuracy was not affected by .001 concentricity.

Most of us plan methods to yield perfection but in fact it never happens as well as we want. I find it hard to believe that given a proper chambering reamer that is piloted and the absense of side pressure on the reamer it must follow the bore.

From what I read from alberta canuck it seems he's an incredibly finnicky lathe man. Congratulations!!

vapodog,

I’ve done it with a hand held tap wrench on the reamer while it was supported by the tail stock so I could “feel†the reamer cutting...but had never tried hand holding a reamer with a pair of vice grips in a spinning barrel before. You must have some serious hands and arms on you!

I do like Chic does...I mount a floating reamer head to my quick-change tool post and use the carriage feed to move the reamer into the barrel, held with a four jaw chuck, with the majority of the barrel going out through the spindle bore and through a plastic bushing in the spindle bore to help keep it centered and supported.

The lathe carriage is geared allot faster than the tail stock and you can insert and remove the reamer much quicker than with the tail stock ram.

I have an experimental project in the works where I will be boring and chambering hundreds of 12 inch sections of 6061 aluminum bars and I need to have a set up that will work really fast and accurate, so I can pump these suckers out.

quote:

I have an experimental project in the works where I will be boring and chambering hundreds of 12 inch sections of 6061 aluminum bars and I need to have a set up that will work really fast and accurate, so I can pump these suckers out.

Maybe this will help.....I once chambered a double rifle after the barrels was joined. I did it by mounting them vertically in the milling machine and chambered from the quill.

Can you do this too?

quote:

Originally posted by vapodog:
I have actually seen a production shop chamber barrels. This shop actually bores the chamber.they do not ream it.

I asked about concentricity of chamber to bore and was told that their tests showed that as long as the chamber was concentric to the rifle bore w/n .001 TIR all was fine and that they had no trouble doing that. Accuracy was not affected by .001 concentricity.



Hunting rifle accuracy differences are probably not detectable when TIR varies no more than that. There are so many other variables in shooting, especially in "the field", that minor chambering or alignment defficiencies are usually "screened".

-------------------------

Most of us plan methods to yield perfection but in fact it never happens as well as we want.



10-4! That's one of the reasons I have to work hard at it to get chambers to my own standards.

------------------------

I find it hard to believe that given a proper chambering reamer that is piloted and the absense of side pressure on the reamer it must follow the bore.



That is certainly correct for the nose of the reamer, assuming a decently fitting pilot. However, it can make for some oversized chambers to have the nose of the reamer bear off in one direction, while the tail of the reamer is held in a position which was previously well aligned but no longer is, due to a crooked barrel bore.

-------------------------

From what I read from alberta canuck it seems he's an incredibly finnicky lathe man. Congratulations!!

Yeh, I admit it's kind of a disease. Probably from doing my own barrel work when I was active in benchrest and was fitting & chambering my own barrels well enough to win at the national level 10 years ago. In top level competitive benchrest, the secret is to control every variable possible ahead of "Commence fire" time. Leaves you the time when actually shooting to try to deal with the variables you can't control.

Chamber concentricity with the bore, barrel fit to the action, and similar compulsiveness impulses are just variables. If you can build in control of them, you don't have to worry about them when a match or a national record is on the line.
-----------------------------

Frankly, I'm sorta relieved to be back just mostly shooting my childhood era lever guns right now.....when I can shoot at all.

quote:

Originally posted by vapodog
Maybe this will help.....I once chambered a double rifle after the barrels was joined. I did it by mounting them vertically in the milling machine and chambered from the quill.

Can you do this too?

I actually tried that idea, and it works, but the set up in the lathe using the bushing in the spindle bore is faster and more accurate for what I am doing. I’m not boring and chambering for a rifle, but I need extremely tight concentricity between bore/chamber and outside diameter of the finished product. I have a Smithy lathe/mill/drill combo machine and I can swivel the mill head to allow working on long stock off the side of the machine if I have to.

I could probably build some sort of holding fixture/jig for upright drilling that could match the set up I have in my lathe, but it seems a waste of time since I have pretty much got my lathe set up for this now, and it works perfectly for what I am doing.

quote:

I have actually seen a production shop chamber barrels. This shop actually bores the chamber.they do not ream it.

You tweeked my interest. What shop was that?

quote:

Originally posted by D Humbarger:

quote:

I have actually seen a production shop chamber barrels. This shop actually bores the chamber.they do not ream it.

You tweeked my interest. What shop was that?

Me too!

quote:

You tweeked my interest. What shop was that?

maybe that was confidential information.....so I'll say as much as I can and still keep the lid on...ok?

The shop was a CNC shop in Minneapolis MN They bought barrel blanks from Wilson and nachined them for a customer that uses them in a semi auto.. They actually was boring the .223 chamber.....a damn small boring bar I must say.

quote:

Originally posted by vapodog:

quote:

You tweeked my interest. What shop was that?

maybe that was confidential information.....so I'll say as much as I can and still keep the lid on...ok?

The shop was a CNC shop in Minneapolis MN They bought barrel blanks from Wilson and nachined them for a customer that uses them in a semi auto.. They actually was boring the .223 chamber.....a damn small boring bar I must say.

That's really interesting info Vapodog. Thanks for sharing it. Must say, I sure wouldn't want a chamber of that length cut with a boring bar small enough to do that work!

As probably everyone here knows, one of the basic cautions learned in Machine Shop 101 is that generally one can expect to get a lot of tool flex when cutting holes that are deeper than 3 times the cutting tool diameter.

So, to be cutting a chamber that is made with a boring bar that is likely about .100"-.125" diameter or so (it has to fit into the .255" or thereabouts neck of the .223 Rem chamber), there is likely to be some genuine care & skill needed to keep from getting a LOT of tool flex. Especially when the machine gets over an inch into the chamber...that's a hole more than 10 times deeper than the diameter of a .100" boring bar!! Flexing cutting tools means loss of control over hole dimensions, and in this case the "hole" is a bottle-necked cartridge chamber.

quote:

Originally posted by vapodog:

quote:

So, to be cutting a chamber that is made with a boring bar that is likely about .100"-.125" diameter or so (it has to fit into the .255" or thereabouts neck of the .223 Rem chamber), there is likely to be some genuine care & skill needed to keep from getting a LOT of tool flex. Especially when the machine gets over an inch into the chamber...that's a hole more than 10 times deeper than the diameter of a .100" boring bar!! Flexing cutting tools means loss of control over hole dimensions, and in this case the "hole" is a bottle-necked cartridge chamber.

This tool was a "coolant thru" tool that actually looked like a .223 cartridge in size with a single cutting edge. High pressure coolant actually flushed the chips foreward thru the barrel. The chamber was roughed with a three flute carbide reamer and the final cut with the boring bar was about .005 per side.

I was impressed with the speed and finish they got.

Aha! That sounds more like what is normally called a "spade reamer" than a boring bar. Spade reamer is another name for a single-fluted reamer.

So, rather than using a boring bar, sounds as if they were using a regular roughing reamer, then using a spade-type finishing reamer.

That is a much more sound practice.


(A true boring bar set up would not have a cutting edge for its entire length. Rather, it would have a short length cutting edge at the front of the bar (either made as part of the bar, or inserted into it). That edge would cut as the tool was inserted into the work, but would also have to be moved sideways on an angle to make the shoulder, then pushed deeper to make the chamber neck.

This sounds like a semantics to me. What is being described sounds like nothing more than a modified reamer with one cutting edge rather than multiple ones, and the ability to inject cutting fluid during the process.

I’m not sure why that would cut a chamber significantly faster than a regular reamer would.

I’m not sure why that would cut a chamber significantly faster than a regular reamer would.[/QUOTE]



Rick - Hi! Glad to see you up and around this a.m....

I doubt if a spade reamer will cut any faster than a regular multi-fluted reamer, in most situations. In this specirfic application, though, I can see why they MIGHT want to use the single-fluted reamer rather than a standard one for the final pass. First, the sides of the reamer which were not making the cut would not have to be pared away as much as when making additional cutting flutes. That will leave the reamer a bit heavier and less inclined to flex. Second, it may give a bit more useable "beef" to put the lube hole through.

Knowing how a lot of "job shops" think, that will likely make them feel better about pushing the reamer faster and counting on the high pressure lube flow to keep the chips cleared away. I wouldn't count on that, but the incidence of chip-scarred chambers probably is somewhat reduced...just probably not totally eliminated. Especially as they are only making one shallow pass with the spade reamer, they no doubt felt that they could get away with that.

I don't really care who was doing the cutting, but I'd sure like to know who was selling those barrels on their guns. I'd consider buying my firearms from someone who wouldn't accept that approach to the work. (That's IF the reason for using the spade reamer was to increase the speed of the chambering....it might have been done simply because it is easier and quicker to sharpen a spade reamer when it needs it...which it will if you're cutting a lot of barrels.)

Hey, Alberta Canuck...did you get my email the other day?

I’m hardly what I would consider a machinist...but I do tinker around a bit with my Smithy combo machine and have done a bunch of boring, drilling and reaming. This process sounds like “snake-oil“ to me if it is to be used for something as critical as a rifle chamber.

To add my two cents worth, I chamber in the headstock. I chuck the shank in the chuck and use a piece of Delrin to center the barrel. I turn a Delrin rod until it is a tight fit in the through hole, and then bore a hole till it fits the barrel at a position near the left end of the spindle. I have found that a lot of barrels can be held by a surprisingly few number of Delrin bushings.

For holding the reamer, I use a rather hefty tap holder on the reamer shank, and use the tailstock feed to push it. A live point will fit into the index hole on the back end of the reamer. I use my left hand to hold the tapholder handle just off the lathe bed so I can feel the cut. ALWAYS USE A TAPHOLDER THAT WILL REACH THE BEDS! I would never recommend any holder, tapholder, vice grips or whatever which can swing in the lathe. You are just asking for a broken arm or worse.

Rick -

Hadn't had a chance to check my "spam trap". Sure enough, it was in there. Will have to go make sure you are on the "always allow" list. Still have to feed the livestock, so will get back to you privately soon after that (this afternoon at the latest).

quote:

Originally posted by Rick 0311:
Hey, Alberta Canuck...did you get my email the other day?

This process sounds like “snake-oil“ to me if it is to be used for something as critical as a rifle chamber.

I assume (I know, bad thing to do....) you are talking about the spade reamer process?

quote:

Originally posted by Art S.:
To add my two cents worth, I chamber in the headstock. I chuck the shank in the chuck and use a piece of Delrin to center the barrel. I turn a Delrin rod until it is a tight fit in the through hole, and then bore a hole till it fits the barrel at a position near the left end of the spindle. I have found that a lot of barrels can be held by a surprisingly few number of Delrin bushings.

For holding the reamer, I use a rather hefty tap holder on the reamer shank, and use the tailstock feed to push it. A live point will fit into the index hole on the back end of the reamer. I use my left hand to hold the tapholder handle just off the lathe bed so I can feel the cut. ALWAYS USE A TAPHOLDER THAT WILL REACH THE BEDS! I would never recommend any holder, tapholder, vice grips or whatever which can swing in the lathe. You are just asking for a broken arm or worse.

Art,

I use the same set-up with the plastic bushing...but I would disagree on using a tap handle that won’t clear the bed of the lathe. I was taught that the idea is to be able to let go of it if the reamer grabs, and have it (and the reamer) spin free while you shut down the lathe.

I’ve had this happen and have never even come close to having the handle smack my hand when I let go of it.

I'm the guy who taught Chic how to chamber a few years ago. He was taking one of my classes at Trinidad State College. I've been chambering barrels for about 35 years. I have used both methods of chambering; through the head stock of the lathe and using the tail stock. I wrote a book a year or so ago and there is a chapter on this subject.

When I chamber a barrel these days, I use the head stock method with a plastic sleeve to help center the barrel on the out board side of the lathe. I use a JGS floating reamer holder. I mount the floating reamer holder in a boring bar holder. I have a method for aligning the bore of the boring bar holder and the lathe's spindle.

But which ever method use use, one of the keys for cutting a good chamber is clearing the chips from the reamer as often as possible. The gear ratio found in he lathe's carriage allows me to clear the chips faster and more often. Use plenty of cutting oil on both the barrel and reamer.

If you are going to think about buying a floating holder, I've looked at the all. Avoid the tool made Clymer, I've had students bring them to class and destroy there projects. The unit produced by Pacific Tools looks interesting but I think I'll stay with JGS.

If you use the tail stock method, hold on to the reamer with a lathe dog. Hold on to the reamer with your fingers pointed away from your body so the lathe dog can slip through your fingers if the reamer binds, when pull your hand away from the barrel. Then turn off the lathe and clear the chips and apply more cutting oil.

In both methods use the slowest spindle speeds possible. The slowest speed in back gear. Rearmers always give you a better surface finish with slower speeds.

We haven't set the date yet, but I will be back taeching at Trinidad State next year. Most likely one of the classes I will be teaching is Basic Rifle Barreling.

Mark,

I ordered your fine book awhile back and your chapter on chambering was extremely helpful for my project.

Your specs, diagrams and photos for jigs, tooling, and machine set ups alone is worth the price of the book.

A wealth of knowledge in a small package. Thank you for sharing that knowledge with us fledging metal butchers.

"OF HISTORICAL INTEREST ONLY"

Guys, I am not suggesting anyone try this, but the first chamber I saw cut was with a shop made spade reamer. In the late 50's, reamers were expensive. I was working after school in a small gun shop when the smith barreled a 98 using a surplus 30 cal machine gun barrel. He turned a blank from HSS with a long pilot a few tho over the bore. (this part took the bulk of the time) He milled a full length cut excluding the pilot and the shank. He then took off a few tho off the cutting edge side of the pilot with cloth backed abrasive until the pilot just fit in the bore. (the old shoe shine trick). After a quick heat and quench with oil, he drilled out the bulk of the chamber and finished with the spade bit. Total time to make the bit and chamber the barrel was about two hours. (I got there after school and was home for supper.) It takes that long just uncover the lathe and get a set up dialed in these days.

I don't think he ever used "store bought" reamers, much too expense. He also chambered by feel to fit factory cartridges, I am sure he did not use go/no-go. He made rifles for hunters, and made most of his own tools and fixtures. He had old cone drive machines, but knew how to use them. Remember, in those days, few hunting rifles achieved what was then referred to as the "mythical minute of angle". I do not have any of his barrels, but I bet a chamber cast would show they were quite close. I don't think the chambers I cut look any different than those he cut (but I know the rifles shoot better, maybe due to other factors.)

I have used shop made spade reamers infrequently for "one off" cuts. The problem is a very short life, they dull quickly, and with no clearance, get clogged by chips very easily. I don't have the skill or confidence to try this for a rifle chamber, especially with quality reamers from multiple sources available at reasonable prices.

Roger

Hi All,

I want to express my appreciation for all of the responses to my questions, a true education. I have the fine book by Mark Stratton and have read it several times, however, I have always felt more confident doing anything, once I have been exposed to and had an opportunity to evaluate as many ways as possible to do it. All of you have made it possible for me to proceed with a fair degree of confidence.

Just to fill in some blanks, my lathe is a 1987 14x40 LG SuperMax, it has a new chuck, steady rest, and a taper attachment, it will do metric and inch threads. I have made a Delrin “centering plug†similar to that used by Mr. Stratton and intend to thread and chamber in the headstock. The lathe has speeds of 40 to 2500 RPM is quite heavy and I doubt that I will wear it out though I will try.

Please accept a heartfelt “Thank You†for your contributions, I am sure that I will have more questions and can only hope that you all will be as gracious and forth coming in the future.

Thanks,

Marcos (elalto)

Well I'm glad you all like my book. I spent a lot of time putting it together. Sometimes you read a magazine article but they don't go into enough detail to be useable. I think the key is to have a digital camera sitting next to your machines with the willingness to use it. I've started on book two, there were a lot of things that slipped by me on the first one.

RogerR -

A good description, and perfectly put. What you described works very well, so long as one has a good idea what the finished reamer should look like...which any _experienced_ old-time (or modern) barrelsmith will have.

I too use home-made spade reamers for some cartridges where I don't feel like investing in a multi-flute commercial reamer, and they are relatively easily made from round stock of the proper size.

They are easiest made quickly if one has a tool post grinder, but still quite possible using simpler tools to shape the reamer. As has been pointed out they have less chip clearance than multi-fluted reamers in most instances...at least when made for cutting steel... Still, it is possible to make the cutting edge angle and back clearance such that they do rather well so long as you cut slowly and clear often. I like to go slowly anyway. With me the question is one of precision rather than production shop speed, so I don't mind taking up to half a day to do a good job of chambering, threading, and polishing

I also use an already fire-formed cartridge case for a headspace gauge in SOME chamberings...usually for my own BR rifles where I want to make sure the chamber is a really close fit to a specific lot of brass, and where I will be using the chamber myself, not cuttng the chamber for someone else's use.

As you know, using a cartridge case for a headspace gauge involves more "feel" than vision, so one does need to know what the bolt closing should feel like when using a case as a gauge.

quote:

...I mount the floating reamer holder in a boring bar holder. I have a method for aligning the bore of the boring bar holder and the lathe's spindle.

Mr. Stratton:

Would you please describe your method of aligning the bore of the boring bar holder? Seems to me that there must be some clever way, but so far any such trick has managed to escape me so I indicate a rod. Thanks.

Glenn

Hi hst,

I know that Mr. Stratton is a sign of respect, but Mr. Stratton was my father and he died some years ago, Mark will do just fine.

Here's who I align the bore of the boring bar holder and the spindle of the lathe. My boring bar holder has a .625 bore. My JGS floating reamer holder has a .625 arbor. I have another jacobs chuck with a .625 arbor. I use a 3-jaw chuck on the lathe. The lathe's 3-jaw has a .00003 run out, but it doesn't need to be this accurate because of the floating reamer holder.

I place the jacobs chuck in the boring bar holder and move the lathe's carriage toward the lathe's chuck so the jocobs chuck meets the lathe chuck. This is for squaring the two chucks. Now the jacobs chuck and lathe chuck are square to one another. Next, I mount in the lathe's chuck a turned rod with a center drill hole in it face. I mount in the jacobs chuck a Starrett center finder. This tool has an edge finder on one end and a center finder on the other. I adjust the boring bar holder with the center finder, I move the lathe's cross feed into place and raise or lower the boring bar holder into position. When done, I will set the cross side handle to zero, this is just in case I bump the handle, I know where it needs to be. I remove the jacobs chuck and insert the floating reamer holder. I set the lathe into the slowest speed in back gear. Mount the reamer into the floating holder and away you go.

All along the reaming process I check the progress by using the GO gauge. When you get close to the end, place a dial indicator against the carriage and you should be able to adjust the headspace to at least .001. I like to set the headspace a little tight. The bolt should tense up on the GO gauge. It doesn't come close to closing on the NO GO gauge.

If you want a more on this subject buy a copy of my book. The chambering and a whole lot more on setups, tools and fixtures. Everyone seems to be quite happy with it.

Mark:

Thank you for your reply and for the information. What you suggest makes perfect sense and I will see what can be done to adapt it to my tools. I have a pretty good idea as to what I will do, and it will be a lot easier than what I have been doing.

I would be interested in your book. How can one obtain a copy?

Glenn

Hi Glenn,

Just give me a call and use a credit card or send me a check and mail it to:

Mark Stratton Gunmaker
PO Box 813
Mukilteo, Washington 98275

My phone number is 425-745-8309

The cost is $75 plus $5 shipping

Mark -

Are you using a "Set-True" type of 3-jaw chuck?

Most of the 3-jaw chucks I see home-machinists buying these days have more like .001"-.002" run-out due to the tolerances in the automatic opening/closing mechanism. Just curious as to the "brand" you are using.

Might help steer the non-professional lathe person away from a 3-jaw chuck that might be less than precise....

Thanks.

You know, it doesn't make any difference weather your lathe has a .0003 runout or .005. If you use a good floating reamer holder it will be the difference between a good chamber or bad.

Do you think all rifle barrels are straight? You've gotten a tube from a good manufacture that when you place it between centers there's a run out. You don't need a dial indicator to see it. Sometimes it the fact that it's just the outside turning that's off center, maybe it's not. Sometimes you don't know where the problem is, but with a good floating reamer holder, the pilot of the reamer will follow the bore no matter where it goes or how off center it is.

Another thing, you get on these message boards and you get a tool and die maker and he likes only American made machinery. He thinks that everything else is crap. There are some good machine that are made somewhere besides the USA for a lot less money. We are rebarreling rifles not sending people to the moon. If you can rebarrel a rifle and have a 7 1/2 pound shoot a minute of angle or less, your lathe is just fine. Now someone help me off the soap box.