What threading "aid" should I use in threading a barrel?
I have seen or heard about a million of them, but just want to know what makes cutting the easiest.

What kind of an "aid" did you have in mind?

A good sharp cutting tool will help, preferably something in carbide. Making certain that the threading tool is centered vertically on the work piece will help make the cutting cleaner as does the use of slow speeds, light feeds and plenty of good sulpher based cutting oil.

Sometimes it's tough to see where you are when the threading tool is covered with oil and metal chips, so employing a dial indicator to locate the exact point to withdraw the cutter from the work would be a good idea to keep from accidentally jamming the cutter into the shoulder and destroying things.

Other than that, practice, practice, practice...

Good luck,

Malm

Malm,
I thought faster speeds with carbide were the order of the day...
Pat

A center guage is nice to ensure your cutter is square to the workpiece. Thread measuring wires are a big help. A digital readout is real nice too.

If the lathe you are using is capable, its a good idea to thread barrels "upside down and backwards" by running the lathe and feed in reverse with the cutter held upside down in the toolholder. By doing so, you don't have to worry about hitting the shoulder. You will have to have a relief groove to start the tool off in.

Of course, you should set the compound to 29 degrees and use that to advance the tool until you are about .010" - .015" from your final depth, then switch to the cross slide. There is a feed formula for this, but I don't have it handy. Hope this helped - John

Get the Carboloy "Snap-Tap" internal and external holders and inserts. Makes life so much easier.

I set up with compond at about 29 deg. Mobilmet S122 water soluable mixed 2 or 3 to 1. Works well for everything including chambering.

I turn thread tenon to about 0.015 oversize. With cutting tool against the work zero Cross Slide and Compound. Use the Compound to advance depth of cut and Cross Slide to pull out. First pass of couple of thousands just so I can double check with thread guage.

With a nominal 1.000" thread tenon and 16 TPI the difference between Major and Minor diameter is about 0.060. I need to advance tool about half of that. With the Compound rest to advance the tool I will take a 0.010 cut. Remember that this will read about 20 thousands on Compound set to 29 deg.

I'll take another 0.010 cut then a 0.005 with two clean up cuts. I'm looking for a good class 3 fit so from here I will try screwing the action on to the barrel by hand. Without removing barrel of course.

Last night I was threading a barrel for a Howa. Thought I'd be fine taking another 0.005. Ended up with a slightly loose fit so had to start over. I cut 1 or 2 thousands then try the fit. When I can screw the action on with the help of a 12" wooden dowel through the action I call it good.

When threading I move coolant hose out of the way when approaching the shoulder. Don't want to slam into it.

I make those last few cuts by advancing the Cross Slide.

The water soluable coolant keeps barrel and tool or reamer cooler.

Wally

Damn- I've done about a million treads and never heard of a threading "aid" except maybe a Hardinge Toolroom Lathe. What do you mean by a threading "aid"?-Rob

Rancher,

True enough, faster speeds and carbide generally are the rule, but when one is starting out and learning to thread, I would recommend slow speeds and using carbide. Regardless of the speed or feed, there is nothing quite like replaceable carbide inserts...

Malm

Beelzebubba,
I have often wondered if anyone actually used thread measurin wires to do barrels. Since gunsmithing school, I have been working in a Cutting Tools plant. Basically I grind threads on taps (on CNC machines). When I was first intro'd to wires my first thought was that they would be an excellent way to get a snug fit on the threads. Anyway, out of curiousity, what are the most common barrel thread pitches? I might have to actually start collecting some wire sets. Thanks, Sean

Malm,
A few weeks ago, I took Mark Strattons octagon barrel and mauser tricking out class at Trinidad (2 weeks worth) and he was using a neat little gizmo with replaceable inserts called a Thinbit. They were not the triangular type but they were set up for 55 degree Mauser threads. They also have 60 degrees. He cautioned all of us that if you broke one of the mausers you owed him $20 as they were a special grind. Of course because I was not holding my tongue quite in the right place and grabbed the wrong friggin feed or some such crap, I forked out a 20 along with a few others. BTW, do you put your tongue on the left side of your mouth or the right??? Concentration can be a bitch.

The 2 weeks were fun, got a couple of barrels done, one of them half round half octagon and both of them chambered and installed on some mausers, surface ground 6 actions and learned Marks neat tricks on building custom bases, quarter ribs and a few other things that are way above me. Had a good day at Whittington center and watched Mark shoot a 3/8" group with MY RIFLE (the fickle thing) at 200 yards in a pretty good wind. Remind me not to shoot against him for money.

Chic,

$20.00 a whack does a lot to sharpen ones focus... I have been known to occasionally break, or, outright destroy carbide inserts, but the inserts I use only cost me $10.00 per lapse. Of course having a machine equipped with a good foot brake helps.


Malm

Malm, this was a clausing with a foot brake. I just was not cognisant enough or skilled enough to use it. Should have not worried so much about tongue placement, lol.

I thread my barrels with both carbide and cobalt vee tools on my lathe from 90 to 130 rpm depending on the set up and tpi. Use good cutting oil.

Also have a couple of set ups that I cut RH threads backwards. I mount the cutter upside down and run the spindle in reverse, then thread away from a shoulder. Its slick, most of the time I am doing 50 to 100 parts so you see why that way is easy.
You just have to be very careful in the set up and be sure to set the feed in the correct direction.

Have been running a CNC lathe making screws at my other job lately. Cutting threads at 2500 rpm with carbide and coolant in 8 to 12 passes. Makes the old lathe seem kinda slow

Jim Wisner

Jim,
Sure, throw another variable in for me to get confused. After a few more of these it may get easy but all I could think of was how much work on this octagon barrel I was going to screw up.

Chic,

Speaking of "concentration" and "foot brakes", I learned early on that having someone standing over you while you're machining has two possible draw backs. 1) Becoming distracted from what you are doing causing you to hit the foot brake in an attempt to avoid a major catastrophe, only to discover that 2), the person is much closer than you though and that the idiot has inadvertently placed his foot "under" the foot brake...

Malm,
Thanks for your answer regarding speeds when using carbide inserts.. I'm always anxious to hear the opinions of those that have
"been there".. As you mentioned, I'm sure it is better to start at slower speeds and go on to higher rpm's as your skill increases.
Pat

I think the best way to learn threading is to practice on bar stock before placing your barrel between centers. Take the phone off the hook, turn off the radio, place your dog in the other room and think about what your doing. The tooling system I use is manufactured by Thinbit, and I have 55 degree carbide threading bits custom ground. There also available in 60 degree. Another key to good threading is using the compound instead of the cross-slide for tool depth adjustments. Rotate the compound to 29 1/2 degrees (for a 60 degree thread) and feed in. Now the threads will be cut with only one of the tools cutting edges. If you use the cross-slide to make the feed adjustment both sides of the tool cuts and the chip flow isn't as good and the tool plows through the steel. Use a good cutting oil. Use the slowist spindle speed in back gear. Set up a dial indicater so you know when to disengage the carriage, and when the carriage comes to a stop, allow the cutter to remain in place. You will need to cut a relief grove anyway for the receiver to seat, let the threading tool show you where the grove need to be. I say this because after teaching basic rifle barreing for years, I've had students try to disengage the carriage and back the threading tool out at the same time. Practice, Practice, Practice...

[ 08-09-2003, 22:15: Message edited by: Mark Stratton ]

Triggerguard 1

The CNC lathe is a DSM that has a Omniturn conversion on it. We use it to make the small gunscrews. Most of the old Stevens and Winchester and even Remington used ODD threads.

From .108 to .250 dia is what we have been running lately. Of course the only halfway standard was the Remington M 11 Screws at 36 tpi.
The Old 1886 and 1894 Winchesters are from 30, 33 1/3, 35 1/2 and some 48 and 56 tpi, while the Stevens are either 26 or 30 tpi.

For this CNC lathe we are using a threading insert made by Circle Precision.

Jim Wisner

Those Omnis are neat little machines for doing the class of work that you're describing. Many times I wished I had one on the floor for making the floorplate catches for the model 70 trigger guards.
Aren't those about $25-$30,000?? That's a lot of machine for those prices.

I've used circle products before, and was very pleased with their boring bars, but they're very pricey. Considering that you're using a gang tooled setup, you don't have a lot of options in the insert and tool selection.
Several years ago I gave a lot of thought to developing a line of turning tools that would handle Sandviks inserts for the gang tooled lathes. At the time we were running an American Way lathe. Trying to run any decent production was pretty difficult until we made our own tools that would handle the more common inserts. One of the tool reps for Sandvik dropped in one day and noticed what we were doing. He seemed pretty impressed, so I figured it wouldn't be long before my idea would be sucked up by the big boys, but so far nothing I've seen would indicate it.

Sorry, but you have no idea what kind of budget I have!! I cannot afford a lathe, and probably will never own one! I was not talking about that, i was talking about a compensator! I am not that strong, but have to use a die. I am not that strong so I just want something to make it easier. I will, of course havee the barrel all prepped and not tapered. No w that I think about it, I really didnt describe what I was doing at all.

Randm'man,

I probably did more to screw up this thread (no pun intended) than you. I thought by your post, you wanted some input on something to help make threading easier, so I just naturally assumed that you meant with a "lathe".

Sooooo, for helping to screw this up, and you are partially to blame here as well, here's what I will do. Give me a call and I will see what I can do to help you thread your barrel. You may have to scrub a couple of guns to pay for it, but it will be done right.

Malm

Randm'Man,

Don't feel too bad, even if you didn't I sure learned a bit from this thread! My only regret is that I live too far from SLC, otherwise I'd help you scrub guns so I could learn some more!

Malm, once again you do a nice thing.....

Is this a great forum or what?

Mark

Malm,
I'm impressed with your generosity and willingness to help folks.

Very nice,
Pat

Matt - is the Sandvik tooling as versatile as the Kennametal TopNotch? Or does it do so well at threading that it outweighs the versatility advantage of TopNotch?

Scott

I have a question here. I'm pretty much learning as I go. I was makeing a jacket forming die the other day and had a problem while cutting the 7/8x14 threads on the outside. I set the cross feed to 30deg and had a 60deg replaceable carbide tipped bit with a new bit inplace. I took my first pass, then used the cross feed to turn in each succesive pass. I checked fit with an RCBS die nut. Everything was looking fine until I took a couple of final .001" passes, then the thread peak rolled over towards the left. I grabbed some emery cloth and sanded it down. It works but isn't exactly right. What did I do wrong?

I wouldn't set the compound at 30 degrees. While you don't want to be cutting equally on both sides, setting the compound at 30 degrees gives you no margin for error. Take a look at your thread form under magnification, and see if it is a nice, clean, symetrical 60 degree "V". FWIW, 29 degrees on the compound is commonly used. Someone else here recommended 29.5 degrees.

Other than that your major diameter could have been slightly large as well, the lock ring could have been undersized. It's one of those "I'd have to be there to see it for myself" sort of things.

Scott

Matt - thanks for the recommendation. I too have worked with Iscar, but just for milling, and felt like their inserts wore out way too quickly. As in the cost of replacing the inserts almost took away any increase in profits due to faster production speed.

Scott

Wow.
Thanks, I really did learn something here. I should have problably been a little nicer on the last reply. Besides, its comforting to have such a popular thread. Its not your fault. This will help me out anyway. Besides, its better to have it (knowledge) and not need it, than to need it and not have it.