This is an adjustable live center that I made from a boring head to taper barrels. I have to remake the cone as it was made from the wrong material & is way too soft! It works OK but you need to take lite cuts. Please excuse the photos. My monitor is going dark & I really see the true brightness of the images.

Doug

I guess the obvious question is why? I thought this is what the tailstock offset screw is for. You have created additional unsupported length of the tailstock reducting rigidity. With the tailstock offset and the barrel back in at minimum extension, you should be able cut up to the design limits of the lathe. A well lubricated dead center increases rigidity even more. The more rigid the set up, the heavier the possibly cut and the better the finish on the cut.

If you want to measure that offset, why not put a dial on the offset screw?

Roger

Doug

Once you get it perfected, and if you want to test it, I have a barrel you can recontour for me. I will let you work on it for free. Hows that for a deal?

I use it & it works well. The reason for it is that I HATE adjusting the tailstock.

Doug,
I understand why you did it and it is a great idea. No one likes screwing with the tail stock.
I much prefer a taper attachment but your boring head idea is much superior to fooling with the tail stock and then trying to get it straight again. I spent most of 5 years running an old tool room lathe. Somewhere between 5,000 and 10,000 hours of it.

Nice pictures D,

Very clear. Definitely one of those "duh, why didn't I think of that?" ideas. It also has possibilities for those "well worn" lathe ways. Without messing with the tailstock (which is centered for the distance from the head at which you do most of your work) you can adjust your tail radially to go directly to the sweet spot. That would likely be much quicker than 1/2 x, 1/2 y, re-check.

Kewl, muchos gracias, danke schon,
LD

PS,

I'm glad to see you had your live center circumcised. Now you can make kosher rifles.

LD

Roger-

from your post, I am assuming you do not run a lathe. Getting the tailstock center back to "dead-nuts-on" is a monumental task. It may look easy to those who have never done it (sure looked easy to me back before I stood in front of a lathe on a regular basis), but I can promise you it takes A LOT of time to get it just right. This time is unproductive and you get paid exactly zero dollars for resetting the tailstock center, all the while your fixed costs are bouncing along thier merry way and customer's work is sitting in the corner gathering rust.

Also, rigidity of the live center vs. adjustable center, while theoretically correct, plays no practical part in turning barrels. If a barrel is a little off one way or the other, it is no big deal. when chambering or doing action work then yes, you strive for maximum accuracy. But when it comes to changing a barrels outer dimensions, well, we are not making a nuclear plant here. A little more slop on the tail stock end has no practical effect.

If there is a custom gunmaker using a dead center these days, I have not met him. I am sure there are some out there, but would guess that most of them are old timers or too cheap to buy a live center. Surface finish on a barrel is a real bear anyway. You are turning a long, limber piece of hard steel. There are things you can do to reduce chatter, but using a dead center will not make a measureable difference.

I mean this in a purely teaching way and hope you take it as such. I said EXACTLY the same thing you did back before I actually had to do it to my own equipment. Guys told me the same thing I just told you, except they used a lot more colorful language!!!

BTW-where do you live? I am moving back to CLoquest in about 3 weeks. Just got back from a 3 week trip up there.


ireload2-

I have not seen a taper attachment that will come anywhere close covering the range of the length of a barrel. This is especially true for smaller lathes typically used in gunshops. Even large lathes usually have a tape rattachment with little more than 12". Of course you could turn the 12" and then resetup, but it is easier/faster and just as good to make an adjustable live center or, Gid forbid, offset the tailstock.


D Hamburger-

Thanks for getting back to me on this. I did make one for myself about 6 or 8 weeks weeks ago but have yet to use it. I have a barrel to recontour, but have not been able to get to it in the rotation yet. And with the above mentioned move, it will be a few months before I get to test drive it.

I posted the question on a home machinshop BBS and got some leads on the parts I needed. I bought a boring head with a #3 MT shank and bought a small live center with I think a #2 MT. I chucked the live center in my 6 jaw and turned the Mt shank to a .5" shaft. I then cut it off to where the small center just stuck out a little from the face of the boring head. My live center is a little larger than yours, but I really did not have the time to burn to make one that is a little smaller. Maybe I will one day when I get caught up on everything, but the odds of that happening are pretty slim!

Guys, I asked because I have not seen or used one of these. I learned to make chips long before I ever saw a live center, and yes, I use a live for most turning now. My WWII vintage Regal is old and tired, so I have a set of pointed centers I line up, and I turn each end of a test bar when I reset the tail after turning a taper. It is the way I learned, and like setting a 4 jaw, it really doesn't take much time to get it right. It certainly is not a "monumental task". And you are correct, I do not do this for a living, so my time is mine. I guess I do a lot of things the "old way". If I were on the clock, I certainly would look at these.

Marc, you are right; accuracy is not the point. Flex in the overhang leading to chatter was my condern. I recontoured a dozen 03A3 2 groove barrels back in the 60's,(they were $7 each by the case, and made decent sporter barrels) the biggest problem was dealing with length wise expansion. That may be the reason for the groove in Doug's live center. If that center was turning freely, why the groove?

Marc, welcome back to "God's" country. I am about an hour northwest of Cloquet, in GR. I do my own work, so I have not been looking, but I am not aware of anyone "in the business" in this area. Tim R is busy turning out stocks in Wirt, and there are a few doing minor repairs, but I am not aware of anyone full time on the range. If you are setting up a shop you should have lots of work.

Roger

neato.. I nearly said "looks like a borehead...." and then i READ the text

pretty darn cool!

jeffe
jeffe

I hope I don't sound critical but, the way that setup is hanging out of the tailstock, will, in itself cause the setup to lose rigidity. When turning anythin between centers, the less overhang there is on the tailstock the more rigid the setup will be.

As for setting the tailstock back to zero, try a magnetic base and indicator attached to a faceplate and spin the dial indicator around the center to align it. Helluva lot easier and less time consuming than turning a test bar each time.

Jim Kobe

quote:

As for setting the tailstock back to zero, try a magnetic base and indicator attached to a faceplate and spin the dial indicator around the center to align it. Helluva lot easier and less time consuming than turning a test bar each time.

That sounds like a neat trick Jim. I well know the setup that I made is certainly not the best answer but it does work if you take lite cuts & a piece of broom stick helps too.

Several of you have alluded to the problem of chatter while taper-turning a barrel, a problem which we've all experienced at one time or another. There seems to be some peculiarity involved in turning a long thin cylinder that sets up harmonics and leads to this. I'm sure that I'm not the only one who's ended up with a barrel that looked like a piece of braid after a couple of light passes. God knows I've spent countless hours trying different speeds, feeds, rakes, bits, etc. until I finally luck into a combo that I can live with. Sometimes, even after all of that, you're not able to completely eliminate it. So let's hear from all of you smiths out there! What's your secret to avoid or diminish the problem?

The best is a following rest with air cylinders. Check Jim Stratton's book. I first saw this at Harold Broughtons barrel shop many years ago. A plain following rest will help a bunch. 99% of the time, I will pay the barrelmakers unless something is special.
Butch

Jim

That will work if the lathe bed is in good shape (asuming it is leveled properly). I set the pointed centers nose to nose, then use an 18 inch "dumbbell" between centers and indicate from the compound at the headstock, then down to the tail for a quick final setting of the tailstock. I realize I am only checking the horizontal, but that is all I am moving anyway. I turn most short tapers by setting the compound, and I am more interested in being sure the lathe cuts are parallel for long cylinders. It takes about 2 minutes to put the dumbell between centers and take a very light cut and mic each end. I ahve used the same dumbell for over 30 years, it sits right below the lathe. This way I know I turn cylinders (at that distance.)

Ron

I find that it is much easier to take a very light cut on short large diameter pieces. With barrels, I use a midpoint steady and turn half at a time with lots of oil and a standard shaped HSS tool with the cutting edge honed and the tip rounded slightly. I always take a moderate cut at a fairly rapid feed. I think the flex of the barrel is less, and I get a better finish. I get chatter with light cuts. I do pay attention to the tailstock pressure as the barrel will lenghten. I don't push it until the machine groans, but the chips are blue. I am sure others that do this more have better ways, depending on the condition of their equipment.

Roger

Turning barrels on center with a taper bar is the best way, but you must make the taper bar long enough for your lathe. We had a 1/2in X 2 in. bar that was attached at each end of the lathe so you could run the full lenth without a problem. The cross slide had to be disconnected from the carriage bolt and connect to the taper bar. Chatter was controlled by using a dampener block of wood about 3 inches following the cutting tool. This block floated on top of the barrel with a little amount of weight to adjust for control. The tool bit was more of a square point like 75 degrees. To learn the control of barrel turning try making new taper on barrels from the German 98 of WII. These were some of the hardest to turn and keep straight. Barrel turning and straightening barrels requires a press along with a good eye. I have had to stop turning these military barrels and correct the bending problems. After you have turned a few hundred barrels it comes easy.

I think it is a good idea & i agree with you,i don,t enjoy resetting the tailstock as well. van

quote:

Getting the tailstock center back to "dead-nuts-on"

I have an accurate bar with two centers. I chuck up a piece of scrap and turn a point on it, that will be a "dead nuts center". The bar goes in between that and the tailstock. I then run my indicator back and forth ajusting the tailstock. A 5-minuet job?

As far as chatter, use your steady rest. Cut the taper in two halves. Yes it is a PITA. I believe most of the big boys use a grinding operation to taper a barrel. You could then put the load parallel to the barrel instead of perpindicular to it.

What?
No one has the Brownell's LATHE CENTERING BUTTONS?

Always wondered about the button method. I assume you adjust until a micrometer reads the correct diameter, when the anvil is across the two buttons meeting line, and the buttons are pressed between dead centers??

I think one feels the buttons align between forefinger and thumb.

This is interesting to me because I had the same problem. I run a big machine shop but I gunsmith in my own shop and the lathe I use (which I wouldn't trade for anything) does not have a taper attachment. I also push my chamber reamers with a dead center so I really don't like moving my tailstock once its dialed in. So.. after turning a few between centers with the tailstock offset and pulling my hair out I vowed never to do it again. In my world a good machinist not only hits his mark but he is fast and efficient. My solution was to set the barrels up in one of my bigger lathes and use the taper attachment. No its not long enough to do the whole barrel but here me out. You start by putting your steady rest toward the breech end and cut the taper on the muzzle end. Then move the steady to the other side of the saddle and turn down the breech end. One plus to this is that you can put a double taper on a barrel if you want. You don't get the chatter problems either. You can look at a douglas pre turned barrel and clearly see this is how they do it.

To summarize:

I went from turning 250 rpm .004 feed with High Speed Steel (like watching paint dry) to turning at 500 plus rpm and .010-.012 feed with carbide.

You can also see the steady rest bearing area if you look at a 1903-A3 Springfield barrel. They turned each end with the steady rest then cut the steady rest bearing down to sort of blend.

I ran an engine lathe quite a bit 3 decades ago. No one ever used a dead center to turn a taper if they could help it. Steady rests and taper attachments were the rule. Back then carbide tooling was not plentiful as now. I hand ground the standard Carboloy tool bits with a very deep chip breaker and a very thin edge. This reduced the pressure on the the work piece a lot and helped eliminate chatter. On long work pieces you can monitor the tailstock hand wheel for pressure to prevent bowing of the work piece. It is a bit of an art that you develop..all touch. Running coolant on it helps too.
You can reduce chatter by wrapping the offending work piece with a piece of inner tube.
With the old rocker tool holders you could clamp Vise Grips on at a strategic place to kill chatter too. Even your hand placed against a shaft or tool holder can deaden the chatter sometimes.