Are there any benefits to polishing dies to reduce resizing force?

From what I've been able to find, most think that polishing will help, while others think the polishing wll actually increase the risk of a stuck case.

Has anyone tested the actual benefits/risks of polishing?

I have never polished a die to reduce resizing force. I have polished the inside of one resizing die that got some gunk in it and was scratching the brass on resize.

I think polishing a die that's been kept in good condition is a waste of time. They should already be "polished" during the manufacturing process. Unless it was poorly stored and got some rust inside it, I can't see where it would be necessary. If you had a rough die, I don't see how you could "polish" it enough to make any difference. The steel hardness used on dies is pretty hard stuff. I don't see you truly "polishing" it with normal home garage type equipment.

If I had a normal die that was bad enough to need polishing, I'd probably toss it in the trash and buy another one. Maybe if it was something exotic I would try to send it out to the manufacturer to be saved?

quote:

I think polishing a die that's been kept in good condition is a waste of time. They should already be "polished" during the manufacturing process. Unless it was poorly stored and got some rust inside it, I can't see where it would be necessary.

There are a lot of dies that come from the factory rough that are improved by polishing.
They are Herter's, Lyman especially the older plated dies, Bair, and CH.
I have polished almost every brand you can think of to stop minor scratching. In every case I have improved the finish over the factory finish with 5 minutes work. Resizing force is also improved, especially those with a roungh internal finish such as the Herter's dies.
The finishing process is simple. I use 600 silicon carbide paper wet with light gun oil or WD-40. The die is spun in a lathe chuck at 800 to 1200 RPM. Wash the die clean with WD-40 and compressed air and wipe out with a soft cloth.
This produces a finish better than the factory finish.
One of the things that reduces sizing force is the proper lubricant and polished brass.
I normally use Imperial case lube for routine work.
I have tried one of the high pressure front wheel bearing lubes for case forming and it lubricates better than Imperial. It is too messy for everyday use and is needed only in certain case forming situations.

Go over to Varmint Al's web pages. He has done a good bit of work in this area. Also polishing chambers!
http://.www.varmintal.com
Lots of other interesting information there as well.

muck

Hey SR,

It's too bad you didn't quote the rest of my post, where I said;

"...with normal home garage type equipment."

You use a lathe. Sorry but I find that funny right there, I don't care who you are...

I was reading the May 2009 issue of Rifle magazine and ran across something that reminded me of this thread. On page 15 Gil Sengal was talking about why you sometimes need to do chamber casts of revolver cylinders, "So are casts of chambers and throats to see if they are concentric and not egg-shaped. For some reason there are folks running loose who like to polish revolver chambers. Shiny Oval holes are often the result".

I think that the average Joe who doesn't have a Lathe sitting in his garage might want to be pretty careful about polishing dies. There's probably quite a few shiny oval dies out there..................................DJ

quote:

Are there any benefits to polishing dies to reduce resizing force?

Some dies come from the factory quite well polished. Some do not.

If one has access to a lathe he can do some fine polishing with very fine emery cloth on a stick that has a saw slit in the end and the cloth threaded through the stick.

Clean the die with some solvent first and polish at very high RPM using crocus cloth.

When you're satisfied that the polish is to your liking again clean with a solvent and soft cloth and then lube the die using Imperial sizing wax on a cotton ball and a wooden dowel.

One has to polish a long time with a course to medium grit cloth to remove even a few tenths of a thousandths of an inch but be careful to use a crocus cloth as it's extremely fine and won't remove hardly any measurable amount at all.

Probably one will do as much benefit by simply giving the die a thorough cleaning and relube the die with the wax on a cotton ball.

It would take a whale of a lot of "polishing" to affect a case-hardened sizing die.

That said, die finish isn't as clear cut as some think. A satin finish will hold a surface layer of some case lubes a little better, a mirrow finish seems to work smoother - very slightly - with wax lubes.

Steel wool on a bore brush mounted in an electric drill will do just fine. Flitz on a bore mop will make it gleam.

quote:

Originally posted by Slowpoke Slim:
Hey SR,

It's too bad you didn't quote the rest of my post, where I said;

"...with normal home garage type equipment."

You use a lathe. Sorry but I find that funny right there, I don't care who you are...

Slowpoke
Your sense of humor is somewhat misplaced. the poster did not restrict the question to polishing by hand tools only.
Some threaded mandrels used to turn abrasive and polishing wheels in electric drills
have the same thread as many loading dies.
Those mandrels will permit you to polish a die about as well as a lathe.
I have also polished the inside of dies with a slotted dowel and 400 grit wet or dry.
I have also used a slotted jag in a pistol rod chuck in an electric drill.
There are 2 or 3 other ways that I can think of
that you can do it at home with common tools
I still like a lathe the best.

quote:

I think that the average Joe who doesn't have a Lathe sitting in his garage might want to be pretty careful about polishing dies. There's probably quite a few shiny oval dies out there..................................DJ

Not likely

quote:

Originally posted by Jim C. <><:
It would take a whale of a lot of "polishing" to affect a case-hardened sizing die.

That said, die finish isn't as clear cut as some think. A satin finish will hold a surface layer of some case lubes a little better, a mirrow finish seems to work smoother - very slightly - with wax lubes.

All it takes is about 3 to 5 minutes with 400 to 600 grit silicon carbide paper wet with a light oil. I have polished some really rusty junkers in less than 15 minutes.
Case hardening is hard. Silicon carbide is even harder. It does not take much material removal to clean up a sizing die.

quote:

Originally posted by SR4759:

quote:

I think that the average Joe who doesn't have a Lathe sitting in his garage might want to be pretty careful about polishing dies. There's probably quite a few shiny oval dies out there..................................DJ

Not likely

Never underestimate the damage that Bubba can do with an electric drill and 400 grit sandpaper!


I haven't Rockwell tested the inside of any reloading dies. But with 400grit silicon Carbide I can flatten the bevel of a knife blade at RC 64 with one stroke down a sheet of 400 grit. Grinding away for 3-5minutes at several hundred RPM with a hand held electric drill and you think you can't change any dimensions? You've got to be kidding.

If you just have to polish the insides of your dies you probably should stick with what your buddy VarmintAl suggests and use Flitz or JB Bore. This doesn't have the potential for removing way too much metal like 400grit Silicon Carbide does.

Of course the best solution if possible is to buy a better grade of dies that doesn't need polishing. Though admittedly the better grades aren't always available in some calibers and/or when you need them.


I have no doubt that there are plenty of posters here that can accurately polish dies to glass smoothness given the proper tools and technique. I also have zero doubt that letting Bubba loose with a drill and 400grit sandpaper is an invitation to mess something up. Dremel tools have probably ruined more guns than any other tool, but master craftsman like Duane Wiebe keep a couple of them at hand, trouble is most people aren't Duane Wiebe and should be REAL carefull using power tools on firearms ......................................DJ

The success of the folks I happen to know who have polished dies (and chambers) has been pretty directly proportional to their quality control skills...tools, self discipline, patience, planned approach, the whole nine yards.

I do have one comment on this subject that will probably stir up something. I have more than 140 sets of dies for my own use right now, and have had MANY others in the past. None of them have been hardened sufficiently to be immediately noticeable.

Not one, of any make or era. All cut easily with standard high speed steel lathe tools, or various abrasive cloths. (This does NOT inlude "file-trim" dies. they are indeed hard, at least on the very top.)

I have cut a good many of them down to make "shorty" dies for re-shaping or neck-sizing various cases. In no instance has the cutting been difficult, inordinately slow, or significantly hard on the lathe tools when being cut or polished on the lathe.

I too read the loading tool ads, and note they are all supposedly harder than the hinges of Hell, but for some reason, I just haven't experienced that.

quote:

Alberta Canuck

Just curious, have you checked the hardness of any dies? I'd be interested in how hard they are.

Thanks,

Don

"Grinding away for 3-5minutes at several hundred RPM with a hand held electric drill and you think you can't change any dimensions? You've got to be kidding."

No, I'm not kidding that no amount of polishing a die will change the dimensions. But, YOU ARE!

Surely, as you state in your opening comment, using silicon carbide paper in a die is grinding, not polishing.

I too have cut down and modified quite a few size dies for special tasks. I've not found one that a file can touch, nor a hack saw blade or a high speed drill bit or lathe tool. Every single sizer I've worked on had to be cut with carbide tools or ground with a silicon carbide wheel. The case usually seems to be about 3 to 5 thou thick.

Hey AC, Glad to see you back. You have a PM.
-----

Hey Rammag, I don't remember ever having to Polish the inside of any Reloading Dies I've ever had. Did have to polish the Chamber on a couple of buddy's rifles a long time ago though.

The "Force" used to do your Resizing can also be affected by the size of your Chamber, how stout you make the Load and the type of Press you are using. And another poster mentioned it could be as simple as the type of Lube you are using. So, even if you Polish the Die, you might/might not notice a change in the Force required to do the Resizing.

What kind of Die and Press are you using?

That flitz thing sounds like a good idea.Good Luck

First of all I did a little searching around to find out how hard reloading dies are. It seems to vary a good bit.

Forster hardens thiers to RC 58-60:

http://www.forsterproducts.com/Pages/dies.htm


Harrell says that std 416 stainless dies are only 45 Rockwell but theirs are RC 55:

http://www.6mmbr.com/catalog/item/1433308/945386.htm


Redding bushings are hardened to RC 60-62 and then titanium nitride increases the effective surface hardness:

http://www.midwayusa.com/viewP...productNumber=888335

Lyman says:

"Each Taper Crimp die is heat treated to an RC50 minimum
surface hardness."

http://www.lymanproducts.com/l...ies-and-Die-Sets.pdf (page 9 - towards the bottom)

-Wow, only RC 50????


I still haven't found a reference to how hard trim dies are and I just don't have one to stick in the Rockwell tester. Maybe I can google up an answer later, I was on hold to RCBS for 30 minutes and while they were looking up the answer I hit a cell dead zone (I was driving) - nuts, maybe they won't be so busy later, I started off as #23 in the cue!.

quote:

Originally posted by Jim C. <><:
No, I'm not kidding that no amount of polishing a die will change the dimensions.

edit: OP restates this non-bs later in this thread




Ok, anyone who knows ANYTHING about polishing knows this is complete BS. You don't see it as much with all the Matt finishes these days but most older gunsmiths can relate stories of guns near ruined by overzealous polishing, rounded edges, wallowed out holes etc.. Read a couple of Brownells Gunsmith Kinks or other gunsmithing references and you'll get lots of info on how NOT to change dimensions when polishing, and remember this is with felt wheels and polish closer to 4000grit than 400grit.

I have several knives that are in the RC 64 to RC 67 range. Last night I took one of them and with 1 STROKE down a sheet of 400grit Silicon Carbide was able to raise a burr and flatten the bevel. Granted this it was a short blade but it's a lot harder than the inside of any die short of carbide. YOU CAN REMOVE METAL with 400 grit Carbide paper! And metal Harder than anything but a Carbide or maybe trim die.

My Tool and Die Maker/Gunsmith friend said that he needed to polish a die and used a mandrel with some scotchbrite on it with good results. He also said 400 grit silicon Carbide would be a BAD IDEA inside a reloading die. If 1 stroke will remove metal off a peice of steel at RC 64-67 how much is it going to take off a die at RC 58 (or less) spinning at several hundred RPM?

Again I'm sure that there are skilled craftsman here that can polish the insides of dies to whatever degree of finish needed (though suggesting that NO amount of polishing will remove metal gives me serious doubt about some posters). But using sandpaper that can cut as fast as 400-600 grit sandpaper is a bad idea unless you are VERY careful. Bubba and mere mortals should use Flitz, scotchbrite, JB's and stuff that doesn't remove so much metal.

Dies aren't as hard as you think. RC 50?????............................DJ

quote:

But using sandpaper that can cut as fast as 400-600 grit sandpaper is a bad idea unless you are VERY careful.

Actually it pretty easy to polish a die. You have to be a persistent bone head to mess one up. I say that because I have spent more time on an engine lathe than most gunsmiths.

The surface of most sizing dies resist cutting with a file. Rockwell test a file. They are normally about RC 64. I suspect the minimum hardness of a die is RC 58 and most quality dies about 62 to 64. It is not that big a deal to carburize and harden to that Rockwell value.

quote:

Originally posted by DMB:

quote:

Alberta Canuck

Just curious, have you checked the hardness of any dies? I'd be interested in how hard they are.

Thanks,

Don

I have never tested a die with a Rockwell or Brinnell test rig, as I really don't care what the readings are. (I do have a Rockwell tester available, but it is not practical to apply it to the inside of a loading die. It could easily be used on the outside of a die, but whether the die is the same hardness all the way through depends on how it was hardened....and sometimes WHEN it was hardened.)

All I care about is whether I can easily cut them in my lathe. I have had no trouble doing that with any of them YET, and I generally do not use carbide tooling for much of anything regarding firearms. Not that I don't like carbide or don't have it available, just that I have seldom ever needed it for gun-related work. I also prefer to use cutting tools that give their best finish when run at slower speeds, which isn't the case with carbide cutters. Anyway, running at slow speeds allows me to be more careful when working to dimensions well under .001", which I enjoy doing.

quote:

have you checked the hardness of any dies?

87.5 15-N

quote:

Ok, anyone who knows ANYTHING about polishing knows this is complete BS. You don't see it as much with all the Matt finishes these days but most older gunsmiths can relate stories of guns near ruined by overzealous polishing, rounded edges, wallowed out holes etc.. Read a couple of Brownells Gunsmith Kinks or other gunsmithing references and you'll get lots of info on how NOT to change dimensions when polishing, and remember this is with felt wheels and polish closer to 4000grit than 400grit.

Okay, so my comment about "no amount of poslishing" will change a die WAS an overstatment. Clearly, some vast amounts of anything can damage anything and that's not what I expected to be received.

Let me restate it more correctly so I can be better understood;

NO reasonalble amount of polishing a sizing die body cavity with a real polish - meaning rouge, not silicon carbide grit - on a snug fitting soft cloth bob wrapped full length around a dowel will change the diamensions of the die UNLESS the polisher puts inordinate amounts of side pressure on the die with a too small bob for a really long time at 10 to 25 thousand rpms.

NEVER use a Dremel type tool and/or small felt bobs to polish a die, it WILL mess things up. Trying that will only get the polisher an inch or so into the die anyway. And anyone who doesn't know all this has no business attempting to polish a die in the first place!

quote:

Originally posted by Winchester 69:
Steel wool on a bore brush mounted in an electric drill will do just fine. Flitz on a bore mop will make it gleam.

That's pretty much how I rol if I feel the need to polish a sizing die. The better quality dies, RCBS, Redding, etc. are pretty nicely finished.

I threw some old dirty dies in my tumbler with some treated media and it really cleaned them up nicely.

quote:

Originally posted by Jim C. <><:
Okay, so my comment about "no amount of poslishing" will change a die WAS an overstatment. Clearly, some vast amounts of anything can damage anything and that's not what I expected to be received.

Let me restate it more correctly so I can be better understood;

NO reasonalble amount of polishing a sizing die body cavity with a real polish - meaning rouge, not silicon carbide grit - on a snug fitting soft cloth bob wrapped full length around a dowel will change the diamensions of the die UNLESS the polisher puts inordinate amounts of side pressure on the die with a too small bob for a really long time at 10 to 25 thousand rpms.

NEVER use a Dremel type tool and/or small felt bobs to polish a die, it WILL mess things up. Trying that will only get the polisher an inch or so into the die anyway. And anyone who doesn't know all this has no business attempting to polish a die in the first place!

This makes much more sense!...............DJ

quote:

Originally posted by SR4759:
I suspect the minimum hardness of a die is RC 58 and most quality dies about 62 to 64. .

According to the links above (and others if you'll Google "reloading dies rockwell hardness) you're incorrect.

They list dies from being RC 50-60, and the hardest mentioned was bushings at RC 62.

Which is somewhat besides the point. I can show you in 2 seconds that 400grit will remove metal at RC 64 (that YES I have Rockwell tested)..................................DJ

quote:

They list dies from being RC 50-60

They who?
What do you know about die hardness with out relying on Google?
Sizer dies do not cut with a file. Therefore they have to be about 60 min.

"OH BOY, OH BOY, OH BOY! THIS IS GREAT!!" - Flounder, from Animal House

.

SR4759, Ummmm I think DJ actually gave links to the DIE MANUFACTURERS sites,or information about their rockwell figures. That would be 'they', you know, the MANUFACTURERS. And your actual numbers come from........

Like AC said, mine cut very easily with a file.

quote:

Originally posted by larrys:
SR4759, Ummmm I think DJ actually gave links to the DIE MANUFACTURERS sites,or information about their rockwell figures. That would be 'they', you know, the MANUFACTURERS. And your actual numbers come from........

Like AC said, mine cut very easily with a file.

Larrys
A file is generally 64RC. It will not cut any thing much above RC60.
Google is no excuse for not knowing the real thing. Have you ever Rockwell tested anything?
But then again maybe you are filing the seater....

Where do my numbers come from ?
Seven years as a machinist and 30 more years a manufacturing engineer, manufacturing lots of heat treated steel parts.

Some people have trouble letting FACTS get in the way of a personally developed opinion. Some time it just takes a while to sink in, lets hope that's the case.

And yes I've Rockwell tested stuff. I've also worked quite a bit with with metals in the RC 59 to 67 range since I sharpen quite a few high end custom knives (which are often individually RC tested before shipping).

I also in the midst of this discussion took a knive at RC64+ and removed a noticable amount of metal with 1 STROKE on a sheet of 400grit Silicon Carbide paper.

You may not be able to file RC 64 metal, but you sure the heck can work it with 400 Grit!..............................DJ

I just put a brand new mill file on a fl resizing die from Lee and then from RCBS. It failed to remove anything from either. It just skidded aver the die.

Some folks have a lot to learn.

As I said before, the FL sizing dies are 87.5 15-N minimum. Look up the Rc equivalency!

quote:

I also in the midst of this discussion took a knive at RC64+ and removed a noticable amount of metal with 1 STROKE on a sheet of 400grit Silicon Carbide paper.

You may not be able to file RC 64 metal, but you sure the heck can work it with 400 Grit!..............................DJ

If you look at my post above you will see that I said you can polish a steel reloading die with silicon carbide paper.

While you are tangled up in the facts do not try to compare cutting steel with a file and cutting it with silicon carbide. You can cut a file with silicon carbide.

quote:

Originally posted by SR4759:
You can cut a file with silicon carbide.

That's the point! 400 Grit Silicon Carbide sandpaper is too aggressive for Average Joe's to use polishing a die! If the stuff will cut a file it will also cut the inside of your die, possible in ways you don't want.

Rolltop, even SR4759 wasn't suggesting using a file to polish dies......................Dj

quote:

Originally posted by djpaintles:

quote:

Originally posted by SR4759:
You can cut a file with silicon carbide.

That's the point! 400 Grit Silicon Carbide sandpaper is too aggressive for Average Joe's to use polishing a die! If the stuff will cut a file it will also cut the inside of your die, possible in ways you don't want.......................Dj

The average dorked up die needs 400 to 600 grit silicon carbide paper lubricated with light oil.

quote:

Originally posted by SR4759:

The average dorked up die needs 400 to 600 grit silicon carbide paper lubricated with light oil.

My friend the tool and Die maker/Gunsmith fixed his in a couple minutes with scotchbrite. VarmintAl who you used as a reference before recommends Flitz or JB Bore. Why do YOU need to use something so much more agressive?

The answer is YOU don't. YOU are just unwilling to listen.......................DJ

I had E-mailed RCBS to ask about the RC Hardness of their dies a few days ago. Here's the response I got back.

quote:

The Rockwell Hardness of our dies is between 58 and 62 whether a
reloading die or trim die. Have a great day.


RCBS Technical Service/DP
605 Oro Dam Boulevard
Oroville, CA 95965
800-533-5000

...............................DJ

quote:

Originally posted by djpaintles:

quote:

Originally posted by SR4759:

The average dorked up die needs 400 to 600 grit silicon carbide paper lubricated with light oil.

My friend the tool and Die maker/Gunsmith fixed his in a couple minutes with scotchbrite. VarmintAl who you used as a reference before recommends Flitz or JB Bore. Why do YOU need to use something so much more agressive?

The answer is YOU don't. YOU are just unwilling to listen.......................DJ

I have ran a lathe a lot more than Varmint Al and your gunsmith.
What do you know about what is agressive?
Your knife example is a piss poor example. A knife blade has a fine narrow edge that you can concentrate the cutting action of the silicon carbide paper on. A reloading die is all large curved surfaces that you can't put much force against because you have to use a stick to back up the paper.
The smaller bores are really limited because you can't much force on the abrasive.
In the case of Scotchbrite people have using silicon carbide paper before it was invented. Scotchbrite is a pad that does maintain a surface contour as well as silicon carbide paper. Scotchbrite may make something shiny but it is not too great for perfectly maintaining existing contours. You basically have no feel for fine contours using it.
If only slight polishing is done you don't even need the force of a stick, the stiffness of the paper is enough.
Why don't you take a half dozen dies to you gunsmith buddy and polish some with Scothbrite and polish some with silicon carbide paper and see which you like best.

quote:

Originally posted by SR4759:


I have ran a lathe a lot more than Varmint Al and your gunsmith. This is mere braggadocio, you have absolutely no way of knowing this do you?
What do you know about what is agressive? I do have pretty good collection of abrasives
Your knife example is a piss poor example. A knife blade has a fine narrow edge that you can concentrate the cutting action of the silicon carbide paper on. True you can concentrate the force more on the edge of a knife but you don't have to in order to get 400 grit SC to cut. And some of my knives are harder than any reloading die A reloading die is all large curved surfaces that you can't put much force against because you have to use a stick to back up the paper.
The smaller bores are really limited because you can't much force on the abrasive. Why? Because you might cut too much too fast
In the case of Scotchbrite people have using silicon carbide paper before it was invented. Scotchbrite is a pad that does maintain a surface contour as well as silicon carbide paper. Scotchbrite may make something shiny but it is not too great for perfectly maintaining existing contours. You basically have no feel for fine contours using it.
If only slight polishing is done you don't even need the force of a stick, the stiffness of the paper is enough.
Why don't you take a half dozen dies to you gunsmith buddy and polish some with Scothbrite and polish some with silicon carbide paper and see which you like best. I tend to buy a better quality of dies that doesn't need polishing

Again, I have no doubt that with all of your experience on a lathe you can polish the dies with the papers you say. You are still missing the point that average Joe's don't have anywhere near your experience level on a lathe (or do experienced machinists/gunsmiths according to you). Just because you can do something doesn't mean someone else can without messing something up..........................................DJ