Threading stainless steel

bearhunter said:
I suspect you mean a thread chaser?????

I finally did a lot of experimenting and cut the threads with the lathe in reverse at higher speed. All of my cuts were very shallow and I had to make a lot of passes to get the proper finish I wanted. Still it worked well and I did end up getting some cutting oil from a commercial shop for the job. The fellow at that shop is a good guy and gave me about a litre of concentrate to mix with water. I don't know what it is, other than it came out of a pink 25 liter bucket. 1-10 mix ratio and it's very slick on stainless.

My tool base is rigid as are the tool holders, when locked in position. It's an Aloris.

I just wasn't feeding fast enough. This is one occasion when there is a "to slow" for best results speed.

I will look for Chroma-tap.

Thanx

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Click to expand...

No, he means a Die. Makes a male thread.

A Chaser will follow the thread form, with no particular diameter in mind. Though, at one time, it was considered a method for making threads freehand. Very different tool than a die.

Starting a thread on the machine and following it with a die is a handy tool for the times you don't really need anything high tech in the way of thread forms, or in non-standard sizes.
I doubt it would be very cost effective to buy a die for each rifle barrel shank size, though.

A Die.
41FpCpb6uML._SX342_.jpg


A Chaser.
Sorby_890H_Chasers.JPG


Also Chasers...Used in a pipe threader.
images

These actually will adjust to a particular diameter, in the proper holder. A Die Head, as opposed to a Die Stock, which holds the top type.
 
trevj said:
No, he means a Die. Makes a male thread.

A Chaser will follow the thread form, with no particular diameter in mind. Though, at one time, it was considered a method for making threads freehand. Very different tool than a die.

Starting a thread on the machine and following it with a die is a handy tool for the times you don't really need anything high tech in the way of thread forms, or in non-standard sizes.
I doubt it would be very cost effective to buy a die for each rifle barrel shank size, though.

A Die.
41FpCpb6uML._SX342_.jpg


A Chaser.
Sorby_890H_Chasers.JPG


Also Chasers...Used in a pipe threader.
images

These actually will adjust to a particular diameter, in the proper holder. A Die Head, as opposed to a Die Stock, which holds the top type.
Click to expand...


Thanx, I'm familiar with thread chasers and taps and dies. Used a lot of them in my day. I know you were being informative and sincerely appreciate it.

The die you show in your pics is similar to the thread chaser I was talking about other than it's designed to be in a holder. The type I'm thinking of has hex sides for use with a wrench. Comes in handy for cleaning up things such as flange bolts or wheel retaining lugs.

The dies I normally use are similar to the die you show but have a split, with an indent on each side so that the die can be closed for a loose fit and even set for a very close to spec dimension.

The chasers you show are new to me. I have a set of four sided chasers that cover most common threads. The threads on pistol barrels aren't included on them. They are also designed to cut several threads at one time, instead of just cleaning up one at a time. I have special files with the proper angles for that.

The tooling you show is from a Rigid or similar Threading/cut off machine used for pipe or threading large steel retaining rods. Good stuff and works well.

The threads I was cutting were on a stainless steel pistol barrel insert I was installing on a prohibited S&W Mod 617. The owner of that revolver wanted to retain as much of the original profile as possible as it was part of an inheritance and needed to be converted to a restricted length continuous bore. The old barrel was cut off at the shoulder, and drilled out to accept the threaded sleeve with new shoulder to make the overall length within restricted length parameters.

Everything has to be true to the axis of the bore and of course the frame.

Brownelles along with a company out of the UK has thread chasers, dies and taps of appropriate dimensions. They aren't cheap but I don't believe I could get the threads close enough to the shoulder with a die or straight enough to keep the pistol accurate.

Anyway the job is mostly done. I just have to painstakingly profile the new shoulder to match the barrel profile, polish and fit it properly to the cylinder gap. Then go through the process of having it verified and reclassified.

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The hex thread cleaning dies are pretty much about on par with Trudeau's leadership skills, as far as a thread "making" tool is concerned.

They are ok for what they are meant for, which is cleaning mung off threaded pieces, and pounding the odd dent back into line.

A die with a split and an adjuster, either in the die stock or built in to the die itself, is ok, but you can buy dies that are actually capable of making a thread to an actual tolerance, rather than just somewhere near nominal, so you see a lot more big dies that are solid like the one shown.

While the pipe threading chasers were simply the first handy pic I found, they also resemble those used in a die head. Once you chip a big enough chunk out of one of the set, then you pretty much braze them on to handles to use like the hand chasers.
 
Hand Skills said:
I know I'm a bit late to the party, and the job is almost done but I noticed no one suggested annealing the part.

I'm not a gunsmith, so I assume there's a reason it hasn't been suggested. Mainly curious for my own sake.
Click to expand...

There shouldn't be any need to anneal the part if I do my part correctly. Also, some types of stainless don't react well to such things, depending on chrome content etc.

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bearhunter said:
I suspect you mean a thread chaser?????

I finally did a lot of experimenting and cut the threads with the lathe in reverse at higher speed. All of my cuts were very shallow and I had to make a lot of passes to get the proper finish I wanted. Still it worked well and I did end up getting some cutting oil from a commercial shop for the job. The fellow at that shop is a good guy and gave me about a litre of concentrate to mix with water. I don't know what it is, other than it came out of a pink 25 liter bucket. 1-10 mix ratio and it's very slick on stainless.

My tool base is rigid as are the tool holders, when locked in position. It's an Aloris.

I just wasn't feeding fast enough. This is one occasion when there is a "to slow" for best results speed.

I will look for Chroma-tap.

Thanx

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thread chasers are meant to clean and straighten threads as opposed to cutting them, as mentioned above a die is what I meant.
the water based coolants are okay, but most are just that, a coolant for keeping high speed tooling (and the work) cool. some good ones have cutting oil properties but a good cutting fluid helps a lot, the chroma tap i mentioned can be used to fortify coolant for cutting as well as be used as a stand alone cutting oil. heres a link but i usually get 1L cans because a little goes a long way https://cuttingtoolpickers.com/index.php?cID=23&pID=1945.

glad to hear you got it sorted, post some pictures of your handiwork if the owner doesn't mind!
 
400 series is generally far more machinable than 300 series. barrel/blank makers should be aware of this. Let your supplier know your preference as some of the least machinable also are more heat/erosion resistant.
 
salarguy said:
400 series is generally far more machinable than 300 series. barrel/blank makers should be aware of this. Let your supplier know your preference as some of the least machinable also are more heat/erosion resistant.
Click to expand...

416 is the common grade for barrels, but i have never seen a liner personally.
 
salarguy said:
400 series is generally far more machinable than 300 series. barrel/blank makers should be aware of this. Let your supplier know your preference as some of the least machinable also are more heat/erosion resistant.
Click to expand...

The people from Green Mountain are pretty decent. When I phoned them and told them what was happening they sent me another barrel at their expense and paperwork.

They also felt that the billet used for hammer forging was from those with metallurgy appropriate for AR and other high pressure rifles.

This barrel was being used for a 22rf and needed a lot of machining to reduce its diameter to be used for a sleeve which would also need to be profiled and threaded at one end to match the original barrel on the pistol after it was drilled out and the liner fitted. High pressure wasn't a concern and the rate of twist was way to slow for for any high pressured cartridges.

They know their stuff. The new barrel is a quite a bit easier to machine but it's not as hard as the original barrel on the pistol, which I doubt will ever be a problem.

Thanx for all the advice.

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My advice as a machinist, put the carbide inserts aside unless you are willing to run them at about 300 to 500 surface feet per minute (sfpm) which would be over 1000 RPM for a 1" diameter shaft. Any slower than that and you are going to be fighting with galling, tearing, chip buildup on the edge and chipping the insert. Carbide needs heat from high surface feeds to work properly.

How I do this type of stuff at work:

-Grind up a threading bit with decent rake back and away from the leading edge(the one toward the chuck), about 10 degrees and hone it with a stone.
-Set your compound to 29.5 degrees and zero your dial.
-using the cross slide, move in and touch off the part and zero your dial for the x axis.

-When threading, only move in with the compound rest for depth and keep returning the cross slide to the same zero position.

- this will allow the tool to cut on one edge, reducing pressure on the part and tool, as well as allowing smooth chip flow for difficult materials.

Turn stainless at about 40 sfpm max, so roughly 160 RPM for a 1" shaft. This can be run slower with HSS but no faster.

I wrote the above not to be pedantic, as you have threaded before but I just want to share for those who are starting out.

Hope that helps.
 
aric84 said:
My advice as a machinist, put the carbide inserts aside unless you are willing to run them at about 300 to 500 surface feet per minute (sfpm) which would be over 1000 RPM for a 1" diameter shaft. Any slower than that and you are going to be fighting with galling, tearing, chip buildup on the edge and chipping the insert. Carbide needs heat from high surface feeds to work properly.

How I do this type of stuff at work:

-Grind up a threading bit with decent rake back and away from the leading edge(the one toward the chuck), about 10 degrees and hone it with a stone.
-Set your compound to 29.5 degrees and zero your dial.
-using the cross slide, move in and touch off the part and zero your dial for the x axis.

-When threading, only move in with the compound rest for depth and keep returning the cross slide to the same zero position.

- this will allow the tool to cut on one edge, reducing pressure on the part and tool, as well as allowing smooth chip flow for difficult materials.

Turn stainless at about 40 sfpm max, so roughly 160 RPM for a 1" shaft. This can be run slower with HSS but no faster.

I wrote the above not to be pedantic, as you have threaded before but I just want to share for those who are starting out.

Hope that helps.
Click to expand...

Thanx for this.

It's pretty much what I normally do with stainless.

My issues in this case were from the extremely HARD type of stainless that was used to hammer forge this barrel.

I've turned threads on Black Star barrels, which I would call hard, without much trouble. I initially useded carbide because the HSS bit was dulling and needed to be sharpened with every pass.

I was lucky enough to be loaned a tungsten composite bit that had been previously ground and it did the job very well.

I've since done a half dozen jobs with stainless just to become more familiar with a couple of different types.

Your very well informed directions are bang on. With stainless, SPEED is very important along with lube/coolant.


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Quote Originally Posted by salarguy View Post
My machinist and gunsmith friends make the male threads"on the lathe", not end/die cut.

billbmcleod said:
Agreed. Only commenting on a previous post.
Click to expand...


I do all threading on barrels and truing receivers on a lathe.

When I drill and tap, I will usually insert the tap into the drill chuck to keep it straight to the axis of the bore. Add a bit of lube, turn by had to start, then apply the handles to finish the job. Nothing worse than threaded canted holes.


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I missed the part where you mentioned that it was also hammer forged. Being that stainless steel work hardens easily that will be a heck of a fun barrel work with now that it has been hammered in to shape. I know 416 stainless it fairly easy to work with in it's regular temper/hardness but not sure about it's hardness after it has been hammered if that it what was used. Get some good high cobalt HSS and let us know how it goes.
 
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