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eww1350
06-03-2011, 09:57 AM
I have notice that many barrel fitters are cutting a thread relief on the tenon when chambering new barrels...I have had friends ask me to set back a barrel to freshen the throat and that thread relief sure leaves an ugly uneccessary gap...I do not cut a thread relief just for that reason...you never know when you need to remove several threads to change a chamber without making the barrel too short....
Take a LV barrel at 21.750" and you want to set it back .500' or so every 300-500 shots and you can see where a thread relief ruins the usability of that fine barrel...

Just some observations...


Eddie in Texas

Dennis Sorensen
06-03-2011, 10:54 AM
If the action does not require a relief I don't cut one on the barrel... but you have to on some actions...

4Mesh
06-03-2011, 12:17 PM
Eddie,

you can always stick the relief in the action.

Cheechako
06-03-2011, 01:06 PM
Some purists look at a relief cut as a way to avoid the extra effort needed to thread a barrel without one. Maybe so, maybe not. I usually do not cut one but I have all the time in the world to thread without one, or to fix things up if I happen to hit the shoulder.

I have set barrels back when they had a relief cut and I don't think it hurts anything to have that gap. After all, it is hidden and you can always use the old machinist's excuse of, "Hey, that's exactly how I wanted it to look." ;)

Ray

YOOO VINNY
06-03-2011, 05:09 PM
Please explain, how do you thread full depth hard to a shoulder with NO relief ?
Are you tapering out to crest dia and relieving the first few threads in your reciever ?
Or what am I missing ???

4Mesh
06-03-2011, 05:20 PM
Most receivers have some relief in them. Either that, or the action has a recoil lug or other spacer. No further relief required.

Cheechako
06-03-2011, 05:49 PM
Vinny

It's not possible to cut a full depth thread hard to a shoulder, but if you are sober, turn off the Tv, and lock the door, it is possible to come pretty darn close. And, the pucker factor isn't too high since a wreck can be easily fixed.

But, as 4Mesh said, it isn't really necessary, regardless.

High School Machine Shop teaches you to always cut a relief on any thread that comes up to a shoulder, but a full thread looks more professional. And your friends will be impressed. Never underestimate the importance of peer acknowlegement.

Ray

Butch Lambert
06-03-2011, 06:54 PM
Several years ago before I started doing my own, I had one set back 3/8". It now had a .390 thread relief. They did not have to pick up the old threads. Everybody shook their head, but it shot lights out. It doesn't take but a few threads to hold it sufficiently. I thread to the shoulder or about .040 from it.
http://i51.tinypic.com/2q2jm8m.jpg
Not a good photo, but you can't get much closer without crashing into the shoulder. It really is easy as I have travel dials and set it to "O" when I want to disengage the half nut. It ain't hard and it will not hit the shoulder if you watch your Trav A Dials or indicator. It ain't necessary to thread to the shoulder but it looks better.
Butch

frwillia
06-03-2011, 09:55 PM
I recently fitted a barrel to an '03 Springfield. It has square threads @ 10 TPI and really can't be done right with a thread relief. So I threaded it to the shoulder. I set up a dial indicator on the ways where I wanted to turn off the motor, let it coast to a stop (from 35 rpm, which didn't take long), then pulled on the drive belt by hand to finish the last half turn or so to the shoulder. I used an HSS bit to cut the threads, carbide would probably have shattered cutting to a stop like that, but with HSS it worked great.

When I'm cutting normal "V" threads I just flip the spindle into reverse (I have a 3 ph drive motor on a rotary converter, do not try this with a single phase lathe!) and back off the cross slide. Works for me.

Fitch

Butch Lambert
06-03-2011, 10:55 PM
Fitch,
What would happen if you just disengaged your halfnut and didn't put it into reverse.
Butch

frwillia
06-03-2011, 11:09 PM
Fitch,
What would happen if you just disengaged your halfnut and didn't put it into reverse.
Butch

Flipping it into reverse with the half nuts engaged keeps the tool pretty much in the groove if my timing backing off of the cross slide is off a tiny bit. Disengaging the half nut stops the carriage but the spindle keeps turning so there is the risk of making a circumfrential cut. Flipping it into reverse, with the tool (cross slide) retracted (I use a cross slide stop when threading, do the feed with the compound) I just let it run, crank the cross slide in after I clear the work, advance the compound a few thou, flip it into forward, and make the next pass.

Truth be told, I didn't give it a lot of thought, I got started flipping it in reverse cutting metric threads that wouldn't pick up again on my imperial lead screw if I disengaged the half nut. In fact I converted the lathe to 3ph for that very reason - doing metric threads. A single phase motor won't plug reverse, it has to slow down enough to engage the starting capacitor.

Fitch

alinwa
06-03-2011, 11:17 PM
OK, let me just get this right.....Fitch you just HIT REVERSE with a couple hunnerd pounds in motion? (I realize that reversing force is probably only 20-30ft/lb but hey..... if it was hooked to my nose it'd hurt)

I know of hydrostatic drive heavy equipment where that's normal but that's because of bleeders and popoffs.. and routing. Does a three-phase offer such a smooth cushion that there's no shock or what?

al

TRA
06-04-2011, 12:54 AM
Does a three-phase offer such a smooth cushion that there's no shock or what?



Yup, just like power tappin.

Al, ya sayin ya never, oh gosh

3ph will direct reverse.

alinwa
06-04-2011, 01:09 AM
cool

4Mesh
06-04-2011, 02:15 AM
Al,

That doesn't mean you can just run em full throttle and hit reverse like you can with a 3 phase dc motor. Nothing really enjoys that sort of treatment, and I've even seen drives fail on big dc stuff when that's done too much. I know the one lathe at work has a spec on it that says what rpm you can reverse it at. Seems to me it's around 300 rpms. On any motor, a stalled rotor condition causes current to go through the roof. That's what you have when you hit reverse. Just don't be surprised if you do it at too high a speed and everything comes to a coasting halt after the breakers blow. Done at proper speeds, you should never see that.

alinwa
06-04-2011, 03:51 AM
I don't see myself ever doing it. But for production work in a machine shop environment I can see applications.

In this vein I used to rent a lot of equipment doing my own stuff. I BROKE a lot of rented equipment, generally by being too "gentle" with it. I'm now a perty good operator, I can get work done without every real equipment guy in the area getting knotted up just lissening to me work. :) I've grown up around machines, machine shops and machine people and can state as fact that I've actually learned how to drive certain rigs by watching the expressions of the other drivers........ so I'm fairly confident that there's a right way and several wrong ways to "hit reverse." :)

al

frwillia
06-04-2011, 06:44 AM
OK, let me just get this right.....Fitch you just HIT REVERSE with a couple hunnerd pounds in motion? (I realize that reversing force is probably only 20-30ft/lb but hey..... if it was hooked to my nose it'd hurt)

I know of hydrostatic drive heavy equipment where that's normal but that's because of bleeders and popoffs.. and routing. Does a three-phase offer such a smooth cushion that there's no shock or what?

al

Al, trust me on this, it works. Really. Why? Well, at the risk of TMI, I'll tell you why it works.

Well, first of all, the heaviest thing in the drive path is my 8" 4J chuck. I don't know what it weighs, but it isn't a lot, so the rotational inertia (Wk^2) is relatively small.

Second, I only do it when I'm threading which I seldom if ever do at more than 50 rpm, usually at 35 rpm, so there the angular velocity squared term is small.

Third, I'm hooked to a rotary converter which be default limits the current to the generated leg compared to a power company supplied three phase source.

Finally, if you look at the drive train, the gear ratio between the 1725 rpm motor and the spindle is about 34.5:1 when the spindle is set for 50 rpm. Inertia is reflected from the spindle to the motor inversly as the square of the ratio, which means the motor is seeing ~0.08% of the spindle inertia under threading conditions - in other words, the motor is seeing conditions not much more than if it was reversing itself. The inertia of the pulleys and the first couple of gear shafts are way more significant than the spindle, but they don't have a lot of inertia to them - and even the driven pulley will see a reduction of something like 1/9. Combine the small spindle inertia (that the motor can't even see much of) with the slow speed (very little kinetic energy) and the limited current and it is pretty much a non event.

I did it from full speed a couple of times as a test for the converter a couple of decades ago when I built it. Lathe slows down over several revolutions then accelerates back in the other direction to full speed. It probably puts about as much heat in the motor as starting it twice at full speed.

I'm running my 2hp 3ph spindle motor off a 5hp idler that's balanced (using run capacitors) to give a voltage of 108% of line between each line and the generated leg and a power factor correction cap that results in about 5 amps of idle current (no load). The whole thing is powered off a 20A 220V single phase circuit and will run the lathe and mill at the same time if I wanted to do that - and I've done that when I was flycutting the surface of a piece of metal in the mill feeding it as slow as the feed would go - mill motor doing almost no work.

If I wanted to make the reverse snappier I could turn on my mill (also 2hp 3ph) and let it run unloaded while running the lathe. That effectively turns it from a perfectly (my opinion) balanced 5hp converter into a poorly balanced 7hp converter with more surge capacity. I don't do that because there is no reason to. But I tried it after I built the converter because I wanted to know the limits of the system.

Anyway, if all this hasn't put you to sleep, it works a treat for threading if the drive motor is powered by a converter, or if it is powered from the power company 3 ph line. I've never tried it with a 3ph inverter (variable speed) drive. It might work, but I'd think it would have to be a programmed ramp down and back up, and it might not like it much - but it might work at low speed.

There ya go, everything you ever wanted to know about plug reversing a small lathe.

Fitch

Jim Kobe
06-04-2011, 10:06 AM
If you have a chuck that is threaded to the spindle, it can get mighty interesting when you hit reverse. We used to do tyhat in high school machine shop just for laughs, until we got caught.

YOOO VINNY
06-04-2011, 11:34 AM
OK, Thank You.
I dont see myself ever being concerned with it, as it isent effective for my needs or equipment.
But I understand what you'r refering to and can see how it makes good practice.

Cheers, YV

MilGunsmith
06-04-2011, 11:42 AM
Cut away from the shoulder with the HSS tool upside down and run the spindle in reverse. You can also cut to the shoulder using a Hardinge HLV-H or similar. There are quick retracting atachments that are similar to the Hardinge available.

SGS
06-04-2011, 02:43 PM
OK, let me just get this right.....Fitch you just HIT REVERSE with a couple hunnerd pounds in motion? (I realize that reversing force is probably only 20-30ft/lb but hey..... if it was hooked to my nose it'd hurt)

I know of hydrostatic drive heavy equipment where that's normal but that's because of bleeders and popoffs.. and routing. Does a three-phase offer such a smooth cushion that there's no shock or what?

al

Years ago I worked in a shop that made hydraulic cylinders. They contracted to make a bunch of cylinders for a Japanese forklift company with all metric threads. I ran a large LeBlond Makino lathe and I was amazed to see the 12" chuck stop and reverse from 220 rpm with no fuss whatsoever. We cut metric threads just as Fitch describes and it works! I don't have that luxury with my single phase Jet.

Scott Roeder

alinwa
06-05-2011, 12:33 AM
Again, cool!

:)

al

JonathanK
06-05-2011, 01:01 AM
Heres a video I made while apprenticing of a friend/gunsmith cutting threads cutting threads, this video was helpful to me when I got my own machine

http://www.youtube.com/watch?v=PeGxEvrZH6M&feature=channel_video_title

Leeroy
06-05-2011, 06:41 AM
I've never tried it with a 3ph inverter (variable speed) drive. It might work, but I'd think it would have to be a programmed ramp down and back up, and it might not like it much - but it might work at low speed.

Fitch

Actualy it works, and it probably works better than most rotary phase converters!
You are dead right about the programmable ramp down and back up, but that is only part of the story. Most modern VFD's offer dynamic braking and can be equiped with a suitable brake resistor. Once they are set up and configured to your motor and load, one can go from full speed forward to full speed reverse in complete safety and usualy VERY quickly. They are current limited so the drive will always protect it's self from damage (at the expence of ramp speed).
I have a 2.2KW VFD on my lathe (1.5KW motor) and i can go from full 1800 RPM to zero and back up to 1800 RPM reverse in less than 2 seconds in complete safety. Even with the 8" 4 Jaw chuck on (allthough limited to 1000 RPM with the 4 Jaw). At 300 RPM, reversal is pretty much instant! The brake resistor is about a foot long and nearly 2" dia and rated to 500W continuous power but still gets quite warm after several high speed reversals.
Combine this with the fact that i can dial up any speed between about 6 and 1800 RPM at the flick of a dial, a VFD is the only way to go..
With the cost of VFD's droping dramaticly over the last few years i cannot understand why anyone would be mucking arround with rotary converters.

Cheers
Leeroy

frwillia
06-05-2011, 11:50 AM
Actualy it works, and it probably works better than most rotary phase converters!
You are dead right about the programmable ramp down and back up, but that is only part of the story. Most modern VFD's offer dynamic braking and can be equiped with a suitable brake resistor. Once they are set up and configured to your motor and load, one can go from full speed forward to full speed reverse in complete safety and usualy VERY quickly. They are current limited so the drive will always protect it's self from damage (at the expence of ramp speed).
I have a 2.2KW VFD on my lathe (1.5KW motor) and i can go from full 1800 RPM to zero and back up to 1800 RPM reverse in less than 2 seconds in complete safety. Even with the 8" 4 Jaw chuck on (allthough limited to 1000 RPM with the 4 Jaw). At 300 RPM, reversal is pretty much instant! The brake resistor is about a foot long and nearly 2" dia and rated to 500W continuous power but still gets quite warm after several high speed reversals.
Combine this with the fact that i can dial up any speed between about 6 and 1800 RPM at the flick of a dial, a VFD is the only way to go..
With the cost of VFD's droping dramaticly over the last few years i cannot understand why anyone would be mucking arround with rotary converters.

Cheers
Leeroy

Thanks for the update on inverters. Sounds good. I probably won't go shopping for one any time soon, but it's good to know they are out there.

Why won't I be getting one? Well, as good as inverters may be today, my rotary converter (built 20+ years ago), has never failed to do anything I designed it to do, is about as reliable as gravity, paid for, and isn't broken. If it ever breaks, I'll consider an inverter, but since I built the converter myself, if it ever breaks I can't imagine anything on it that I can't fix for twenny bux.

Fitch

alinwa
06-05-2011, 01:04 PM
Actualy it works, and it probably works better than most rotary phase converters!
You are dead right about the programmable ramp down and back up, but that is only part of the story. Most modern VFD's offer dynamic braking and can be equiped with a suitable brake resistor. Once they are set up and configured to your motor and load, one can go from full speed forward to full speed reverse in complete safety and usualy VERY quickly. They are current limited so the drive will always protect it's self from damage (at the expence of ramp speed).
I have a 2.2KW VFD on my lathe (1.5KW motor) and i can go from full 1800 RPM to zero and back up to 1800 RPM reverse in less than 2 seconds in complete safety. Even with the 8" 4 Jaw chuck on (allthough limited to 1000 RPM with the 4 Jaw). At 300 RPM, reversal is pretty much instant! The brake resistor is about a foot long and nearly 2" dia and rated to 500W continuous power but still gets quite warm after several high speed reversals.
Combine this with the fact that i can dial up any speed between about 6 and 1800 RPM at the flick of a dial, a VFD is the only way to go..
With the cost of VFD's droping dramaticly over the last few years i cannot understand why anyone would be mucking arround with rotary converters.

Cheers
Leeroy

OK, now this is more concievable to me :):) modifications made, or machines made TO allow reversing on the fly are different IMO than just "hitting reverse" on your spinning lathe!

The first post about just hitting reverse just set my teeth on edge a liddle....... no arguments here, no attempt to argue with what IS, just hadda' question the idea a little. For the home hobbyist that's banging the hannle and wondering why the lights flicker.... :)

LOL

al

al

TRA
06-06-2011, 12:18 AM
Just poke the button, or flip the switch. With a Bridgeport type mill it's damned near every day they're being direct reversed, sometimes all day, even all week long. Ya just gotta replace the drive pulleys every few years.

If you break your lathe or mill by reversing it, you need to buy better iron.

Most quality machinery today all have direct tapping capability, so tapping heads are not as necessary as they once were.

frwillia
06-06-2011, 06:37 AM
Just poke the button, or flip the switch. With a Bridgeport type mill it's damned near every day they're being direct reversed, sometimes all day, even all week long. Ya just gotta replace the drive pulleys every few years.

If you break your lathe or mill by reversing it, you need to buy better iron.

Most quality machinery today all have direct tapping capability, so tapping heads are not as necessary as they once were.

I didn't think to mention it, but that's true. I have a tapping head but seldom use it. Instead I set the mill (a 3ph 2HP 16 speed belt drive 9x42 BP clone) for it's lowest speed forward and flip the switch to reverse if the tap starts to slip in the drill chuck, then back to forward. Works great.

Fitch

JerrySharrett
06-06-2011, 09:05 AM
If you set up properly you can cut right up to the shoulder without a thread relief.

Note the shallow thread just to the left of the last full thread on the left. That shallow thread is a portion where the tool is being withdrawn in a coordinated movement of disengaging the half nut while turning the cross slide dial out.

The best way to do this is to position the tool to where you want the thread to stop. Then with the carriage in that position, make a mark with a felt tip marker against the left intersection of the carriage wing and the bedway.

Before starting the threading cuts, practice watching that ink mark on the bedway and the approaching carriage wing. i.e. instead of watching the threading tool, watch this point. Do this a few times before you start cutting threads.

http://s2.postimage.org/3a30aexw/DSCF1523.jpg (http://postimage.org/image/3a30aexw/)

jackie schmidt
06-06-2011, 01:01 PM
I do it similiar to what Jerry is explaining, only I set the actual carriage stop.

I thread at 250+ RPM, to a shoulder. So you really do not need any fancy gimicks, you just need to learn how to do it.

As for Metric, none of our lathes will re-catch a metric thread if you dis-engage the half nut. But they do have an instant dynamic brake, on the Mazaks, it stops in an instant. But then, these machines are desined to take the shock. Some of the more popular "gunsmith lathes" being marketed might be suspect.......jackie

Dennis Sorensen
06-06-2011, 02:43 PM
I set up a dial indicator and set it so the dial is at zero when the tool is as close to the shoulder as possible with a little clearance... when the carriage is backed away the needle rotates and stops in about 40 thou of movement... it is this needle I watch and kick the threading tool out and throw the engagement out at the same time as the needle 'hits' zero. I thread at 45 to 90 rpm depending on how close I have to get... it doesn't bother me if I have to cut a 50 thou relief cut on the tenon, but in the past I set some actions up on a mandrel and cut the relief in the action.

Charles E
06-06-2011, 05:12 PM
I understand there is some pride involved in cutting the thread to the shoulder. But IIRC, about three threads do most of the work, with another 3 or so doing some moderate work. The rest of them are there, as Bruce Thom describes it, "for alignment." From that perspective, you can set the barrel back a number of times before losing any strength.

Am I missing something?

B.Johnson
06-06-2011, 09:16 PM
The lasr four, or five barrel's, I have turned the cutting bit upside down, and run the lathe backward. This leaves nothing for the bit to run into, and you don't need lightning reflexes which I certainy don't have. I made a dedicated tool holder just for this job, and also made a thread grinding jig to keep everything straight. Grinding the bit down to root diamater on shoulder side, you can start the bit right at the shoulder. This method, with these made tool's has for me, made threading just another turning job.

WSnyder
06-07-2011, 12:15 AM
The lasr four, or five barrel's, I have turned the cutting bit upside down, and run the lathe backward. This leaves nothing for the bit to run into, and you don't need lightning reflexes which I certainy don't have. I made a dedicated tool holder just for this job, and also made a thread grinding jig to keep everything straight. Grinding the bit down to root diamater on shoulder side, you can start the bit right at the shoulder. This method, with these made tool's has for me, made threading just another turning job.

When you are running your tool upside down and threading away from the chuck are you using a thread relief to start the tool before engaging the half nuts?

alinwa
06-07-2011, 01:26 AM
When you are running your tool upside down and threading away from the chuck are you using a thread relief to start the tool before engaging the half nuts?


perty much gottabe IMO

You can sure make the relief SMALL though!

:)

al

Ian_Owen
06-07-2011, 06:31 AM
Threading to a shoulder is easy with one of these, acts just like the compound slide on a Hardinge HLV, also you can buy the blades for 60 deg and 55 deg threads.
Since my lathe is 3 phase and has a metric leadscrew I flip the lever to retract the tool and hit reverse at the same time..........Ian

Tool extended
http://i21.photobucket.com/albums/b267/kiwishooter/Workshop/Tooling/Extended.jpg

Tool retracted by the flip of the lever
http://i21.photobucket.com/albums/b267/kiwishooter/Workshop/Tooling/Withdrawn.jpg

B.Johnson
06-07-2011, 07:16 AM
WSynder: The tool will automatically start it's own small relief. Since my lathes have all got threaded spindles I make sure the threads, and shoulders of the chuck, and spindle are clean, and mount with a small snap. I make small cuts with HSS, and measure when close with the three wire method. I have not ever had the chuck come loose, and wii remove with a slight snap as normal. The thing is making light cuts here. I use the same method cutting action threads, but the tool is upside right at the back of the work. This really works well on a blind hole where you certainly do not want to hit bottom.

Jim Kobe
06-07-2011, 10:22 AM
I do it the same way Dennis does except I use more than one revolution on my dial indicator, that way I can watch the thing out of the corner of my eye. When I see it start to move I watch until it hits the zero the second time and desengage the lever and back out the cross slide at the same time. I can usually get to within .005 of the zero everytime and I ain't a young guy with great reflexes. When threading for a metric thread however, it is a different story; I disengage the pulley lever and back the cross slide out and stop the chuck from spinning with my hand, then put it in reverse. A little slower, but it works.

Jim

MilGunsmith
06-07-2011, 07:38 PM
Threading to a shoulder is easy with one of these, acts just like the compound slide on a Hardinge HLV, also you can buy the blades for 60 deg and 55 deg threads.
Since my lathe is 3 phase and has a metric leadscrew I flip the lever to retract the tool and hit reverse at the same time..........Ian

Tool extended
http://i21.photobucket.com/albums/b267/kiwishooter/Workshop/Tooling/Extended.jpg

Tool retracted by the flip of the lever
http://i21.photobucket.com/albums/b267/kiwishooter/Workshop/Tooling/Withdrawn.jpg

Do you have any drawings of the tool? I am used to the Hardinge at work, and would like to have the same setup on my South Bend at home.

WSnyder
06-08-2011, 02:16 AM
Do you have any drawings of the tool? I am used to the Hardinge at work, and would like to have the same setup on my South Bend at home.

That's an Ifanger 3-RS tool holder found on page 31 http://www.ifanger.com/fileadmin/Webmaster/katalog/pdf/01_2006_e.pdf

There are other designs out there like this one http://www.hemingwaykits.com/acatalog/Retracting_Tool_Holder.html

Or this http://www.statecollegecentral.com/metallathe/MLA16D.html

skeetlee
06-08-2011, 06:32 PM
Kinda off topic again but if one were to set back a barrel how much do you need to go? I have a ppc barrel with 650 rounds fired and it still is a shooter but i would like to freshen it up a bit. How far do i need to go to do this properly? I dont have a bore scope so i cant look inside to know for sure. Lee

frwillia
06-08-2011, 06:38 PM
My suggestion would be to look before you leap. You get one setback out of most barrels, doing it too early wastes barrel life ($$$). If accuracy hasn't deteriorated, don't do it yet just to be "doing something".

That said, 650 rounds seems like really short barrel life for something burning as little powder as a 6PPC. I'd think it would go at least 3X that.

Fitch

Butch Lambert
06-08-2011, 07:39 PM
Fitch,
My experience says 900-1000 rounds is tops. It can fail you anytime after that.
Butch

frwillia
06-08-2011, 09:03 PM
Fitch,
My experience says 900-1000 rounds is tops. It can fail you anytime after that.
Butch

I'll take your word for it. That's a lot less than I'd have predicted.

Fitch

JerrySharrett
06-08-2011, 10:31 PM
I'll take your word for it. That's a lot less than I'd have predicted.

Fitch
Fitch, Butch is being generous with the 900-1000 rounds figure. Most give out at about 600-750 depending on the load used/. I wore out 4 barrels last year at about 550-600 rounds with RL-10x. This year I'm shooting SPP210 (IMR4198) and it is not going to be much better. Neither of these powders, though, chase you up and down the clicker as much as V133. I hate that stuff.

I got so spend a couple of days at the Super Shoot with Ron Reiber, Product Manager of Hodgdon and he tells me they ahave a powder coming in early 2012 that sounds really promising for benchrest.

He is supposed to send Greg Walley and myself some to test this Winter.

jackie schmidt
06-08-2011, 10:33 PM
I st a barrel back after the first 300-400 rounds, about .025, just to freshen the throat. I do this again after the next 300-400. I then, on the 3d time, cut the entire thread tenon off and treat it like a new blank.

This is not practicle unless you do your own work. Plus, the way I chamber my barrels in the beginning lends its self to easy set-up for setback.........jackie

skeetlee
06-08-2011, 10:41 PM
So say this barrel is ready to set back, how far should a fella go, or is this an un answerable question

frwillia
06-08-2011, 11:17 PM
Fitch, Butch is being generous with the 900-1000 rounds figure. Most give out at about 600-750 depending on the load used/.

Wow. The barrel life cost per bang is significant. It wouldn't take too long for a serious benchrest shooter to make back the cost of a lathe and the tooling to just fit and chamber barrels (no action truing, just fit and chamber barrels). I'm used to hunting rifles that last a lot longer. But then so does the .30BR.

Fitch

Charles E
06-08-2011, 11:18 PM
Something else to remember -- there are "club match" barrels, "regional match" barrels, and "national match" level barrels. I believe it was Mr. B who remarked that a barrel capable of winning at the national level had 250-300 rounds worth of life. Most of us aren't national-level shooters, but a barrel no longer quite good enough for that kind of competition will still perform at club matches, and may for a period of time.

When you get a real good one, no matter what you shoot -- point blank or long range -- you should save it for big matches.

FWIW

JerrySharrett
06-09-2011, 08:07 AM
So say this barrel is ready to set back, how far should a fella go, or is this an un answerable question
Each barrel presents a different case as not every barrel erodes the same per round fired. That said, if you are setting them back, go a full turn of the threads or multiples of a turn, 0.055" for 18 TPI, 0.062" for 16 TPI, etc. This brings any engraving/stenciling of caliber, neck diameter, etc., back to the same location.

Butch Lambert
06-09-2011, 12:53 PM
Melonite QPQ your barrel and at least triple it's life.
Butch

JonathanK
06-09-2011, 04:42 PM
I have been thinkin bout sending off a barrel or two to be Melonited. I havnt seen any point blank rifles sporting black barrels yet, is anyone out there doing any good with a Melonite/SBN barrel in short range?

Butch Lambert
06-09-2011, 05:03 PM
JonathanK,
This is your contact. The barrels cost $60.
Send to :
MMI-Trutec, Inc.
2609 N. 12th Avenue
Paragould, Ar. 72450
ph 870-236-6920
Attn: Rodney Lanier

Maybe I can get Joel to post an email from the US Army regarding it. It goes into quite a bunch of detail about the process in both their battle weapons and match rifles. I have several black rifle barrels, but I am not an elite shooter. That has nothing to do with the effectiveness of the barrel treatment.
Butch

JonathanK
06-09-2011, 06:18 PM
Thanks Butch! I will be contacting them

skeetlee
06-09-2011, 07:09 PM
I think i may send them a barrel as well. Just how clean does the barrel have to be before i send it out? I can clean it to the best of my ability, but without a bore scope how would i know if it is? I sent a barrel to a fella around here a short time back that i would have bet was spotless but it had some copper in it and a little carbon. I just didnt know. How will that effect the treatment, or will it? Lee

B.Johnson
06-09-2011, 08:53 PM
Is this tread about threating barrels' or when?

alinwa
06-10-2011, 12:26 AM
Melonite QPQ your barrel and at least triple it's life.
Butch

You state this as fact Butch.... is it?

al

Butch Lambert
06-10-2011, 12:52 AM
Yes Al I do. What will it cost you to try it? It was free to you a few years ago. Now it is $60 plus freight.
Butch

Butch Lambert
06-10-2011, 12:53 AM
Is this tread about threating barrels' or when?

b.johnson, it is about or what.

alinwa
06-10-2011, 01:43 AM
Yes Al I do. What will it cost you to try it? It was free to you a few years ago. Now it is $60 plus freight.
Butch

And now, a few years too late some one FINALLY states as fact that BAT's can be blackened......

I think

al

dennisinaz
06-10-2011, 03:43 PM
It is my understanding that most actions can be treated. The ones that cannot be treated are 416 SS actions (Stiller et al) and cast actions such as WBY and Ruger. I had my Defiance Machine action treated but it is CM steel. I had another one treated and the customer took it to have it Cerakoted and the guy grit blasted all the black treatment off and Cerakoted it black!:confused:

This isn't a thread about treatments so I will stop here.

skeetlee
06-11-2011, 12:23 PM
I sure would like to see a picture of something that has been treated. Id like to see just how dark the finish really is? I really really like the look of CM bat actions, so much so that i just ordered one. Lee

Al Nyhus
06-12-2011, 05:42 PM
I sure would like to see a picture of something that has been treated. Id like to see just how dark the finish really is?

Lee, here's a die of mine that was treated.

Treated die (lt.) and untreated die (rt.) -Al

http://img.photobucket.com/albums/v467/tenxal/d1-1.jpg

skeetlee
06-12-2011, 05:59 PM
Thanks Al

Superman
06-15-2011, 01:29 AM
Here are a few more photos for you Lee:

http://i15.photobucket.com/albums/a375/kgunz11/FGW%20Pistol%20Builds/DSC_0251.jpg
http://i15.photobucket.com/albums/a375/kgunz11/FGW%20Pistol%20Builds/DSC_0253.jpg
http://i15.photobucket.com/albums/a375/kgunz11/FGW%20Pistol%20Builds/DSC_0213.jpg
http://i15.photobucket.com/albums/a375/kgunz11/FGW%20Pistol%20Builds/DSC_0097.jpg
http://i15.photobucket.com/albums/a375/kgunz11/FGW%20Pistol%20Builds/DSC_0073-1.jpg

As far as I know, if you contact Joel Kendrick and have a barrel or action to send in, he is going to send you to me unless you have a Type 7 FFL. MMI now only processes barrels for firearms manufacturers and they have a minimum batch fee of $200. If you want 1 barrel done, you can ship that to Freedom Gunworks to be included in the weekly batch. Turn around is typically 3-4 weeks and the cost is $75 per barrel. This post is not to serve as an advertisement for Freedom Gunworks but more as a public announcement for those interested. At one point, I was named the official gunsmith for MMI, as far as I know that hasn't changed.

As for what Butch said, we're seeing a 100% increase in barrel life. I can't claim 3 times the barrel life, but in my experience that would be more caliber specific than anything. The black discoloration is a side effect of the process. It is a thermo-chemical induced hardening process. A barrel COULD be set back after it's been treated, but it would quickly dull a reamer. IMO, it be advisable to replace the barrel vs setting it back.

As for blasting the black off and "cerakoting" it, nothing wrong with that. I have a few theories on rust. Rust is a decay of the surface material, the metal erodes, the brown we associate with rust is the waste evidence of this reaction. If that metal is so hard that the level of degradation is minimal, corrosion or "rust" will be minimal. Surface discoloration generally. I've processed a part, blasted it, then observed the rusting characteristics. With 4140 carbon steel, surface rust will form overnight. On a processed part with the "black" blasted off, even with excessive sweaty hands handling, there is no rust formation. After prolonged exposure, discoloration might appear, but that has been the extent of it. I'm not advocating this to be the norm, just something I have noted in a very small test sample (6" part, but only 1).

I'll answer what questions I can.

Jim Borden
06-15-2011, 05:32 PM
Here is a poor picture (took with my phone)-but illustrates threading up to shoulder. Done on Victor 16x40 lathe at 320 rpm manually. I use a full form ISCAR Threading Tool

http://i243.photobucket.com/albums/ff216/jborden_photos/barrel_threads.jpg

JerrySharrett
06-15-2011, 08:14 PM
Jim, were you using some kind of automatic kickout for the half nut or just using some sort of space age LSD??

Jim Borden
06-15-2011, 08:18 PM
Jim, were you using some kind of automatic kickout for the half nut or just using some sort of space age LSD??

Jerry
No lockouts, no gauges-just watch the tool and shoulder. Been doing them this way since I converted to carbide thread tools about 16 years ago

Jim

JerrySharrett
06-15-2011, 09:18 PM
Jerry
No lockouts, no gauges-just watch the tool and shoulder. Been doing them this way since I converted to carbide thread tools about 16 years ago

Jim

Wow, I'm impressed. Two eyes may help. I've not had stereoscopic vision since 1970.

TRA
06-15-2011, 10:38 PM
Here is a poor picture (took with my phone)-but illustrates threading up to shoulder. Done on Victor 16x40 lathe at 320 rpm manually. I use a full form ISCAR Threading Tool

It still cut a relief. In the heavy duty world, thats where the part will fail. Setting it back won't look pretty either.

4Mesh
06-15-2011, 11:27 PM
Looks pretty darn nice I think. Relief? Everything has some somewhere. And for strength, I'd say there's about zero chance of a failure.

Photos show a lot of sins... Them's nice threads.

jackie schmidt
06-16-2011, 01:00 AM
I darned sure can't do that. ..............jackie

TRA
06-16-2011, 01:52 AM
And for strength, I'd say there's about zero chance of a failure.

A thread like that will last forever in a barrel application, but for a high stress application, that threading up to a shoulder is the worst condition that you could leave it in. It will break right in that relief groove, that the insert cut against the shoulder.

Those threads are more for looks than a useful means to add strength to the assembly. Your only using 4-5 threads, and you don't want them to be on either end, especially if either part was threaded on a CNC.

Jim Borden
06-16-2011, 07:41 AM
A thread like that will last forever in a barrel application, but for a high stress application, that threading up to a shoulder is the worst condition that you could leave it in. It will break right in that relief groove, that the insert cut against the shoulder.
TRA
Those threads are more for looks than a useful means to add strength to the assembly. Your only using 4-5 threads, and you don't want them to be on either end, especially if either part was threaded on a CNC.

There is no relief groove there! The small cut at shoulder was made by the turning tool and is no deeper than the root of the thread (.990 inch). Do the calculations as I have! Those threads were done manually-not by cnc.

Not sure how you are "modeling" threads to make the statement you made. Have done lots of engineering and design of threaded joints for pressure vessel applications.

Jim

Jim Kobe
06-16-2011, 10:14 AM
There is no relief groove there! The small cut at shoulder was made by the turning tool and is no deeper than the root of the thread (.990 inch). Do the calculations as I have! Those threads were done manually-not by cnc.

Not sure how you are "modeling" threads to make the statement you made. Have done lots of engineering and design of threaded joints for pressure vessel applications.

Jim

I am sure a video of the threading operation at 320 RPM is in store for us skepticals!!

skeetlee
06-16-2011, 01:52 PM
In my mind if jim said he did those threads on a non cnc machine then that just goes to show us how talented he really is. I have no doubt to his claim. Jim makes some nice stuff and this is just another example. Looks darn good! I believe I will be making a relief cut when I get up and going. Lee

Lucky Shooter A
06-16-2011, 02:40 PM
JIm,

I'd appreciate it if you'd tell us how you set up and time the end of the threading pass.

Thanks.

A. Weldy

Jim Borden
06-16-2011, 03:12 PM
I am sure a video of the threading operation at 320 RPM is in store for us skepticals!!

Jim
So, you are implying that what I said is not true?

Soon will be out of service until Sunday night. Will catch up then

Jim

Jim Borden
06-16-2011, 03:14 PM
JIm,

I'd appreciate it if you'd tell us how you set up and time the end of the threading pass.

Thanks.

A. Weldy

Will do on Monday. Having hard time answering on my smart phone :)
Jim

Lucky Shooter A
06-16-2011, 04:58 PM
Will be looking forward to seeing your method.

On the other hand, if Jackie can't do it, I probably shouldn't even think about.

A. Weldy

Jim Kobe
06-17-2011, 10:20 AM
Jim
So, you are implying that what I said is not true?

Soon will be out of service until Sunday night. Will catch up then

Jim

Not trying to imply anything. Just am really curious how you can get that close at that speed without anything other than a manual lathe using normal tooling without some sort of kick-out device.

Bob Kingsbury
06-17-2011, 10:43 AM
A small relief does not weaken the thread if it is no deeper than the thread. If it broke at that point, it is because the
loading of pressure is higher there, not because its weaker.

JerrySharrett
06-17-2011, 11:41 AM
A bunch of years ago we had a lathe operator by the name of "Snake" Winegar. When threading he would engage the half nut, lean back and sit down on the work table behind him, jump up and retract he threading tool and disengage the half nut.

He was built like the Old Time Cowboy in Tom T Halls' song Faster Horses, Younger Women, Older Whiskey, and More Money...had to drink a beer to keep his breeches on his hips.

http://www.cowboylyrics.com/lyrics/hall-tom-t/faster-horses-the-cowboy-and-the-poet-12417.html
(click on the right arrow beside the word poet)

Jim Borden
06-20-2011, 09:49 AM
Will be looking forward to seeing your method.

On the other hand, if Jackie can't do it, I probably shouldn't even think about.

A. Weldy

Actually, I believe Jackie and others here can do it. One of the biggest issues with doing it is "CONFIDENCE". 320 rpm is not actually that difficult.
Set Cross slide handle at Top Dead Center. Touch off threading tool on tenon with compound slide. Set "0" on cross slide for the TDC position.

Advance compound about .015 for fist pass. Position Thread tool about 1/4 inch behind tenon. Put left hand on cross slide handle, right hand on half nut and watch thread dial and throw half nut handle closed when correct mark is aligned and hold half nut handle and watch tool and shoulder and get a feel for when to rapidly rotate cross slide handle ccw and open half nut. Second pass .01 deep, third pass about .01 deep and then measure with thread mic or wires and take final pass to make to size

Jim

Lucky Shooter A
06-20-2011, 11:22 PM
Very interesting. I've never tried such a challenge but the word "CONFIDENCE" says it all.

I'd never try to do this on a good barrel without proving it to myself on some scrap---just kidding about agreeing with Jackie that he couldn't do it.

A. Weldy

WSnyder
06-21-2011, 01:21 AM
This weekend I tried it Jim's way. My normal way is to thread at ~150-200 rpm and use a dial indicator set up for ~3/4 revolution to the zero on the indicator with the zero as my disengagement point. I first cut air at 300 rpm to see how quickly I could react to the spinning needle. The fastest I could stop everything was ~.050-.060" of travel beyond my zero on the indicator. At 200 rpm I can stop it in ~.010". With the lathe at a measured 315 rpm and still cutting air I used the tip of the indicator as a stop guide (I rotated the indicator so I couldn't see the dial) and proceeded to see how quickly I could stop everything. At 315 rpm with the indicator tip as a perceived solid object to approach I could shut it down within .005-.010" consistently. With that bit of confidence I put a scrap stub in the chuck and turned a shoulder to thread up to. I tightened the tool post just snug enough to cut a thread without twisting (so if I crashed into the shoulder it would twist out of the way) and proceeded to cut a thread. I was able to cut a thread right up tight to the shoulder that looked just like the one in Jim's picture. Never thought I could thread that fast and never crashed it either. It was much harder to watch a spinning dial attempting to thread at 300 rpm than it was to anticipate a solid shoulder at the same speed.

For an action with a recoil lug where I might want an unturned section for the recoil lug I think I'd just use the tip of an indicator as my stop guide.

All this may be moot for me because my inserted tooling gives great results at 150-200 rpm. I may turn a few more threads at 300 rpm and compare the results later.

RJM
06-21-2011, 08:37 AM
I thought everyone knew to put an indicator against the carriage when threading. Set it so that it picks up & goes 1 revolution to zero when you kick out the tool.

The other thing to do is to use a magic marker to mark the place to kick out.

Also it helps grind your tool so that the point is set off to the left so that it can run closer without crashing into the shoulder.

With these tricks, threading up to the shoulder is not a problem.

Regards, Ron

Jim Kobe
06-21-2011, 12:59 PM
Actually, I believe Jackie and others here can do it. One of the biggest issues with doing it is "CONFIDENCE". 320 rpm is not actually that difficult.
Set Cross slide handle at Top Dead Center. Touch off threading tool on tenon with compound slide. Set "0" on cross slide for the TDC position.

Advance compound about .015 for fist pass. Position Thread tool about 1/4 inch behind tenon. Put left hand on cross slide handle, right hand on half nut and watch thread dial and throw half nut handle closed when correct mark is aligned and hold half nut handle and watch tool and shoulder and get a feel for when to rapidly rotate cross slide handle ccw and open half nut. Second pass .01 deep, third pass about .01 deep and then measure with thread mic or wires and take final pass to make to size

Jim

Okay, I do it pretty much the same way only I allow tworevolutions past the zero on the indicator to sorta give me a heads up what is coming, but 320 RPM is a bit hard to grasp; I guess I must be a lot older and slower. With the indicator set to a stop where I want, I can usually come within .002-.003 of where I want to withdraw. Sorta like when I was younger and a Catholic using their method.

Jim Borden
06-21-2011, 02:29 PM
Jim

One of the key things for me to be able to do it was when I QUIT using an indicator. I watch tool and shoulder and found I was more consistent doing that than with indicator. I have found that the carbide fullform tools cut awesome threads if run fast enough and 320 rpm is about lowest speed I get "shiny" smooth threads. If I run in cnc on 416 stainless, then I use 1000 rpm.

Jim

WSnyder
06-21-2011, 04:08 PM
What I attempted to convey in my previous post was that at 300+ rpm I couldn't use the indicator and if I would have I'm sure I would have crashed into the shoulder. Somewhere upwards of a 200 rpm spindle speed that needle started flying faster than I could reliably track it. By watching the shoulder I could stop it just short of crashing and do it consistently. So after my little experiment I agree fully with Jim, If you need to thread at higher speeds ditch the indicator and watch the shoulder.

Jim, I appreciate your input. It's always a fun challenge for me to see or have someone describe something and get out to the shop and try it.

JerrySharrett
06-21-2011, 05:24 PM
OK, guys and gals, heres the deal about high RPM threading on a manual lathe. You can use proper geometry HSS threading tools, either hand ground or in insert form and get good barrel threads at about 80-140 RPM. You can get good threads with a carbide insert tool but to get great finish it takes about 250-350 on most applications, OK??

If you crash the tool into the shoulder, or worse, into the chuck, your little ChiCom lathe at those speeds, the repair will be about equal to buying a new lathe. Most of those, or any small tool room size lathe for that matter you will suffer more damage than several barrels cost!!! Plus, you might injure yourself in the meantime. If you think it is worth it have at it, just don't just come running back to the forum with a sad story!!

I taught Machine Tool Technology (fancy college name for Machinist) for 10 years and I pretty much know what a just-in-training person is capable of and it ain't threading at 300+ RPM

Jerry H
06-21-2011, 05:41 PM
What do you see wrong in threading upside down and backwards with a camlock chuck at 200-300 rpm?

jackie schmidt
06-21-2011, 07:45 PM
Jerry, if the bottom gibs are tight, (that is what keeps the carriage from rising), then nothing.

When we bore in a lathe where there is considerable overhang, more times than not, we run the tool upside down, usually off the backside............jackie

Dennis Sorensen
06-21-2011, 10:42 PM
I have no intention of seeing how fast I can thread... many years ago I did smack into the shoulder and after all the re-machining, etc. I decided I can do a better job a bit slower and have no worries. I am never in a rush anymore...

TRA
06-22-2011, 12:04 AM
What do you see wrong in threading upside down and backwards with a camlock chuck at 200-300 rpm?

None,,There is no upside down these days. Cutting with the tool on top so the chips can take advantage of gravity is really the preferred way to machine, It's just a bit awkward to most folks.

Something to keep in mind is that the backside of the thread is the most important and needs to be the smoothest. When you are at 29.5 and taking deep cuts you are leaving steps on the back of the thread. You can take it out with a spring pass, but that can be hard on tooling. It's not unusual to see some take 10-20 passes and a couple of spring passes to cut a thread this size.

jackie schmidt
06-22-2011, 12:41 AM
What is a negative helix??

Aside from that, the insertsI use are identicle on both sides, just stick them in a right hand holder turned upside down, and of course, run the lathe in reverse.

As for threading at 350 rpm, I do it because that is where the TiN Inserts I use cut best.......jackie

TRA
06-22-2011, 12:50 AM
?

With full profile tooling, you need to have all your angles in the right direction.

WSnyder
06-22-2011, 01:23 AM
What is a negative helix??

Aside from that, the insertsI use are identicle on both sides, just stick them in a right hand holder turned upside down, and of course, run the lathe in reverse.

As for threading at 350 rpm, I do it because that is where the TiN Inserts I use cut best.......jackie

I've seen pictures of your thread tooling. Aren't they TNMC type inserts or are they something else?

If you run what most would call laydown type insert thread tooling and using an inserted left hand toolholder used to thread away from the chuck cutting right hand threads you would need to run a negative helix anvil in the toolholder under the insert so the helix angle is correct. My mistake in my (narrow) thinking was that everybody running inserted tooling would be using laydown style inserts.

JonathanK
06-22-2011, 01:32 AM
None,,There is no upside down these days. Cutting with the tool on top so the chips can take advantage of gravity is really the preferred way to machine, It's just a bit awkward to most folks.

Something to keep in mind is that the backside of the thread is the most important and needs to be the smoothest. When you are at 29.5 and taking deep cuts you are leaving steps on the back of the thread. You can take it out with a spring pass, but that can be hard on tooling. It's not unusual to see some take 10-20 passes and a couple of spring passes to cut a thread this size.

Parson me as Im still learning...Is a spring pass where you make more than one pass without changing the compound?

WSnyder
06-22-2011, 01:41 AM
Parson me as Im still learning...Is a spring pass where you make more than one pass without changing the compound?

Yes

JerrySharrett
06-22-2011, 06:53 AM
As to spring passes,a spring pass is where you make a pass across the threaded item without feeding the compound. The first spring pass shouldn't cut any or just slightly. If your first spring pass removes any material other then just a very slight amount you have been feeding in too much per pass prior to that.

Make 3-4 spring passes to finish anyway. On small lathes and on an unsupported stub like a barrel tenon you will get a better finish to let the threading tool "burnish" the thread anyway.

jackie schmidt
06-22-2011, 11:40 AM
I guess every pass I make is a Spring Pass, since I thread straight in with the cross slide.

As for the tools, I do not use lay down tools...........jackie

http://www.basstool.com/PDF/CATALOG/591-656.pdf

scroll down to the MTVO-C Holder. That is what I use.

WSnyder
06-22-2011, 02:52 PM
As for the tools, I do not use lay down tools...........jackie

http://www.basstool.com/PDF/CATALOG/591-656.pdf

scroll down to the MTVO-C Holder. That is what I use.

I thought that's what I saw in your pictures (TNMC inserts). I have a similar toolholder in my hand right now from a different manufacturer without the top clamp and it uses TNMC/TPMC inserts as well so I'm familiar with it's capabilities.

JerrySharrett
06-22-2011, 04:48 PM
I guess every pass I make is a Spring Pass, since I thread straight in with the cross slide.

Ase.

Whatever!!!