What's new
What's new

die blank reaming for a resizer die

fireside

Aluminum
Joined
Sep 15, 2009
Location
wa,usa
I'm going to cut out my own reloading die, I 'm getting a blank that is 4140 steel, Can I machine that just as I would ream out a chamber with a HSS reamer ? Any tricks of the trade or differences in machining 4140 ? I have a resizer die coming for the job.
 
Volume 1 of P.O. Ackley's Handbook for shooters and reloaders gives an outline of how the various resizing and seating dies are constructed.

My copy has just come out of 6 years of storage so I've not fully re-digested it.

Harold Hoffman also produced a booklet about making dies, I haven't unpacked my copy yet, but from memory it appeared to be a shameless plagarization of Ackley, with typos as Hoffman's only personal contribution. I also recognized Ackley's section on steels used for barrel making as having been plagarized by Hoffman:soapbox:.

Now to the meat:

According to Ackley most dies are case hardened free cutting mild steel. He also shows sections of various dies.

I would be inclined to cut the internals with a single point boring bar, taper turning attachment and bed stops, that way, everything ends up concentric and truly circular.

What I don't know is how much less than the chamber dimensions of your particular rifle the die should be. I'm guessing that the die will only be used to load for one rifle?

The exact dimensions will depend on the rifle type and your intended use, so a rear locking semi auto (eg a FAL) a stretchy Win '94, or a gun that will be used for quick shooting inn dirty conditions would need a lot looser fitting resized case than a bolt action benchrest gun.
 
For a seater die use the same reamer the chamber was cut with to cut the die.

For a sizing die, most use a sizing die reamer to cut the die with. I would thank it would be difficult, but not impossible to cut an accurate sizing die on a manual lathe.

Gary
 
I'm making a sizing die out of 4140, I asked if it had to be heat treated after it was made and they said no, I suppose it would last longer if it was but then I have the resizer reamer to cut a new die with. I just was wondering how difficult it is going to be to machine the 4140, if it was going to take a different procedure than machining barrel steel or stainless steel. I believe factory dies are heat treated after the machining process. I have made form tools out of screw driver shanks before for forming case heads. I wouldn't think that a brass case would be hard on steel as long as the case is clean.
 
Butch, I am not sure what I said that was so out of line, except maybe I was not clear that my comment about the manual lathe was inresponse to the fellow who was talking about single point cutting the die on the lathe and my comment stands, I would think it would be difficult but not impossible to cut an accurate die. I don't know of anyone cutting rifle chambers on a manual lathe probably because it would be difficult, but not impossible to do it.

Fireside, the 4140 will machine nicely, as far as heatreatment goes, I think it would take a lot of sizing to wear a die out, but hardening will make it slicker also and that is helpful. I have heard talk lately of people having the dies melonite treated which makes them both hard and slick.

Gary
 
Using a single point boring bar is more complicated.

The advantages it has are better concentricity, and with suitable judicious use of stops on the cross slide and bed, you have less likelyhood of going oversize. With very fine feed, and with no adjustment to the cut, it gives a very good surface finish as it cuts from the spring of the bar.

You'll still need to make some plug guages to check on progress, whatever method you use.

Here's an example of a guy who rough cuts chambers using a single point tool and uses a reamer for the final finish. He also sets out his criticism of more general practice of using reamers for the whole process.

Barrel Work, effective 5-18-10

It all depends what you want to achieve, as in all things, 20% of the effort usually gets about 80% of the results, after that the return on extra effort generally declines exponentially.

There are some very interesting views on throating on that site, so I'll start a fresh thread to link them.
 
Yeah, I'm just used to going to a barrel maker and getting a barrel with no questions asked on what it is other than SS or CM. never payed much attention to steel types in that respect until today. Learn something new every day. I will look into heat treatment, I have cut factory dies and found they were harder than snot. so I knew they were harden, what about polishing the inside to a mirror finish ? ( or close to it ) wouldn't that make the die run smoother ? instead of the heat treat.
 
Gary,
I said what I did because you didn't say single point the die in your first post. You just indicated that it would be almost impossible to do on a manual lathe. I have done several in 416R stainless. My PPC die is cut with a reamer with the same dimensions as my chambering reamer with it being .002 under at the shoulder and .003 at the web. I indicate a barrel stub that I make my dies from. Check a brief post right below this one on how I chamber. After the machine work is completed I send it to be treated by Melonite QPQ. It basically case hardens the die to approx 68 RC.
 
I made a resizing die for my 20 caliber wildcat (20 tactical- built the gun too but that is a different topic).

In my situation, the resizing reamer had to be .0035 smaller than the chambering reamer. My die was some unhardened 4140 I think but to be honest I've forgotten. I think you could use mild steel, in fact if I ever do this again I have some 7/8" threaded rod I'm going to try to see how well it holds up.

I do not know how you are planning to ream yours, if the case can be done with a boring bar or do you have to make a reamer? I do know if you try using the same reamer you cut the chamber with you're going to be doing it twice...
 
Making dies

First, Dave Kiff and most reamer makers make undersized die reamers every day. Melonite like Butch said is one method and just having them heat treated is another. Some folks make dies out of 12L14 using chambering reamers. They then are surface heat treated. I have been told that the heat treated 12L14 will shrink a little and make a resonable sizing die.

As for making dies on a lathe it is done every day. Machining 101.

Redding, and Hornady make dies every day with a boring bar on a CNC lathe.

Nat Lambeth
 
As for making dies on a lathe it is done every day. Machining 101.

Redding, and Hornady make dies every day with a boring bar on a CNC lathe.

Nat Lambeth

There is a world of difference between machining a die on a CNC machine and machining a die on a manual lathe which is what the conversation was about.

And then I did not say that it could not be done, I said it would be difficult. I would also say that while using a boring bar may be Machining 101, you better enroll in Measuring 201 to determine if you are boring the die the right size. Once you get the gauges you need to measure it made you will probably be tired of the project and wished you would have ordered a reamer to cut the die with.

And lastly, just because I said it is difficult does not mean I can't do it, it just means I would not want too and if I did I would spend my time making my own die reamer that is much more easy to measure and verify size not trying to cut the die with a boring bar in my manual lathe.

But that is just my opinion. Gary
 
Gary, Nat is a very knowledgeable machinest and CNC machinest. He is a very good gunsmith. I know for a fact that he has had a lot of schooling. He has taught at Trinidad Jr. College. It is considered by myself and most gunsmiths as the premier gunsmithing school in the USA. Not trying to beat up on you, but just giving you a little background on Nat.
Butch
 
Butch, I have worked in the machining trade for over forty years, building lots
of things, that people thought were not possible. I have made a lot of neck finish tooling for plastic bottles, with tolerances of "plus a half, minus nothing"
on a Harrison M350, with 2 axis readouts.
I am making no statements about anyone's abilities, but I feel that the comment about boring a die, on an engine lathe, was an accurate one. It was not said to be impossible, only difficult. A lot depends on the degree of accuracy that you can verify, not that which you can estimate, or assume.
I would agree that boring would improve concentricity, but the setting of the compound angle to the degree of precision needed to get the dia. at the
base of the die, and the shoulder, to both come to +/-.001", is not "easy".
A slight error in setting the tool height, will put you out of the game.
Butch, I have seen photos of your work, and I am impressed.
Regards,
Bob
 
Butch, I have worked in the machining trade for over forty years, building lots
of things, that people thought were not possible. I have made a lot of neck finish tooling for plastic bottles, with tolerances of "plus a half, minus nothing"
on a Harrison M350, with 2 axis readouts.
I am making no statements about anyone's abilities, but I feel that the comment about boring a die, on an engine lathe, was an accurate one. It was not said to be impossible, only difficult. A lot depends on the degree of accuracy that you can verify, not that which you can estimate, or assume.
I would agree that boring would improve concentricity, but the setting of the compound angle to the degree of precision needed to get the dia. at the
base of the die, and the shoulder, to both come to +/-.001", is not "easy".
A slight error in setting the tool height, will put you out of the game.
Butch, I have seen photos of your work, and I am impressed.
Regards,
Bob

There are ways to get anything done, and to check your work. The people that made the varmint wildcats roar back in the day made their own chambering reamers and dies, often more than one rendition of the 219 Donaldson Wasp in the same work day even.

Tapers are checked with a male gauge and dykem hi-spot blu...darn near any vocational high school student, even in their junior year can bore and check a morse taper to get a good taper. IF the case taper in a die was that critical (and it is not, not by any means) then a competent machinist could easily do it. The part being rather small adds a degree of difficulty...but does not make it impossible, not even close.

It would be interesting to set up a contest among the smiths out there in the business to make a die to a blueprint using only an engine lathe, then check the finished parts and publish the results, in a blind fashion without calling anybody out. I think you would end up with amost every due being of the proper dimensions.

Even if you use a reamer you need to CHECK the results anyway, don't you ??

How many people have ever checked the body taper in a reloading die ??

The headspace datum and neck dia are the two most critical dimensions IMHO.

Bill
 
First, Dave Kiff and most reamer makers make undersized die reamers every day. Melonite like Butch said is one method and just having them heat treated is another. Some folks make dies out of 12L14 using chambering reamers. They then are surface heat treated. I have been told that the heat treated 12L14 will shrink a little and make a resonable sizing die.

As for making dies on a lathe it is done every day. Machining 101.

Redding, and Hornady make dies every day with a boring bar on a CNC lathe.

Nat Lambeth

The problem with that Nat is that the shrinkage is not uniform, it might be consistent in a annular fashion.....ie the hole would be round...but carburising seems to "puff up" surfaces. if we took a 2" x 2" x 2" cube for example, and carburised and hardened it, the flats would be puffed up in the middle (for lack of a better term) and if we set it all up and surface ground each flat the last portions to clean up would be the corners...in my experience anyway.

So a die would look pretty weird inside if we could measure it accuratly after case hardening...it might WORK great because we honestly are not asking THAT much from it to do what it needs to do.

Plating will build up on corners too...without doing some really intensive work on custom made anodes to go inside the hole.
 
Bill, I am well aware of the methods of using Dykem bluing to check a taper.
What has happened here is that someone's fecal material was jumped in, for
stating a personal opinion. If you will re-read your posts, you are listing all of the reasons why trying to bore a die on an engine lathe is no as easy as cutting the cavity in a piece of prehardened tool steel, with either a CNC toolroom lathe, or turning center, with a carbide bar, or roughing the cavity, and then finishing the cavity to size with a reamer.
You also state that the body taper is not critical. If that is the "case", how do you hope to achieve the diameters at both the shoulder, and head end of the die? Let us go back to the trade school juniors to which you refered. Most
of them know that if the adjacent side of a right triangle, remains the same, and you change the angle, the opposite side will change. We also know what happens to a brass case that is sized to a diameter smaller than needed.
You refer to the early wildcatters, making dies, on engine lathes. They did so, because there was no better technology, available to them at that time.
Bob
 








 
Back
Top