Lee dies, type of steel?

[dikman]

I need to modify a Lee die (drill it out and machine it on a lathe). Does anyone know if they use hardened steel? I tried a file on one, but I couldn't decide if it was hardened or just tough steel. I'd prefer to avoid buggering up a drill bit if I don't have to.

[nhrifle]

They have a very hard skin but once that is broken through they machine quite easily. You are going to need carbide or ceramic cutters to break through.

[dikman]

Bugger! Sounds a bit like they're case-hardened, but I just don't see them going to that much trouble. I wonder if heating it in the forge and cooling it (annealing) would work?

[zuke]

I had a friend modify a lee die. He used a concrete,carbide drill running slow for the first hole. Then used boring bar's.

[Reg]

Annealing should make them workable.

[DR Owl Creek]

Bugger! Sounds a bit like they're case-hardened, but I just don't see them going to that much trouble. I wonder if heating it in the forge and cooling it (annealing) would work?

I don't know what type of steel Lee uses. From my experience with Lee products, I think it varies quite a bit depending on when and where they buy it, but it's not tool steel. With Lee's case trimmers, sometimes the case length gauges would last a reasonable length of time, and some times they would wear down faster than a No. 2 pencil.

All of the Lee products I've seen appear to use some type of surface hardening treatment that varies greatly. It's probably sometime like this product from Brownells: http://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/color-case-hardening/surface-hardening-compound-sku08000033-27119-52952.aspx?s

I hope this helps.

Dave

[Reg]

I am thinking it might be a 8620 and gas hardened or might even be a 1055 ( Stressproof ) type steel ( for machinability ) and who knows how it is heat treated.
I do know the heat treated area is only on the surface, once you break through it it becomes machinable but still is a bit tough.

[theperfessor]

Not to be picky but 1144 is "Stressproof". Never heard it used for any other steel grade.

[MarkP]

They are probably 12L14 and case carburized; I know other mfg's use 12L14 for sizing dies.

[ProfGAB101]

12L14 is used for the reloading die bodies that have carbide sizing inserts, and some bullet seating dies. Most steel sizing or crimp dies are made with a better/different grade steel, without lead and extra sulfur. Something that responds good to casehardening or heat treat.

[Reg]

Not to be picky but 1144 is "Stressproof". Never heard it used for any other steel grade.

I stand corrected=== and to think I bought it by the ton for 25 years !!!!!

It is a good steel. We used it for shafting in the normalized state. It was tough and very easy to machine, almost like a Ledloy but--
In a pinch we also used it for quick die punches. By eyeball it would come to Rc 55-58 and drawn back to Rc 54/53 A bit low for a die punch but we sure made a bunch of them and I think in many cases they lasted as long as the "factory rolled ".
I was thinking that perhaps it might be used by Lee especially for its very good machinability and the fact with the 44 points of carbon it would take a good heat treat. The dies I made for forming .22 jacket bullets I have used both A-2 and Stressproof and both seem to be lasting.

[dikman]

Thanks guys. Zuke, that idea of using a concrete drill bit had also occurred to me, so I might give it a try first - slow, with lots of coolant.

[nhrifle]

Carbide endmills when used as a boring bar work quite well for this. I have an extra long 4 flute .312" diameter endmill that cuts through with no fuss, and I machine them dry. Turn the spindle speed to a moderately high level, touch off the cutter to the bore, back it out, and make .010" cuts, feeding slowly until the case harden is broken through. Once you reach soft steel the chips will become more long and "stringy" and feed pressure will be decreased. I do this on a 7X12 Chicom lathe, so if you have a "real" machine you should have no trouble.

I have never tried a carbide drill to bore Lee dies, but I would bet there will be a fair amount of chatter.

[EDG]

Put your die body on a gas burner on a kitchen stove. Heat until it is dull blue. Then turn down the heat slowly let it cool to the lowest flame for about an hour then turn off and let it air cool.

It will be soft enough to machine.

[dikman]

Based on what has been written here, I decided to heat it with a MAPP torch, took it to bright cherry red and let it air cool. That did it, I ran a couple of drill bits through it then took to it with a boring bar. Worked like a dream, now I just have to machine the inside piece that I need.

EDG, in my experience taking steel to a blue heat won't anneal it, that merely reduces the hardness (but still leaves it hard). It has to be taken to its critical temperature, usually around a bright red heat and then let cool slowly. Ideally it should be buried in dry ash (or something similar) and let cool over several hours, but I took a chance that air cooling would be sufficient for this.

[MarkP]

12L14 is used for the reloading die bodies that have carbide sizing inserts, and some bullet seating dies. Most steel sizing or crimp dies are made with a better/different grade steel, without lead and extra sulfur. Something that responds good to casehardening or heat treat.

Pacific Durachrome and Hornady New Dimension sizing dies were 12L14 and case hardened.

[dikman]

I'm assuming that Lee would do whatever is the simplest and least amount of trouble, so some form of gas hardening makes sense to me as you don't have to do anything except feed it through an oven. Whatever they do, once it's annealed it machines beautifully.

[MarkP]

It is total cost; machining time, pre heat treat polishing, post ht polishing, tooling wear, etc.

I have had reasonable luck re-treating reworked dies using a special quenchant. Cold water mixed with borax, murphy's oil soap. It will get in the upper 40's HRC. To anneal place in furnace and bring up to 1400 F soak for 10 minutes and turn off furnace and let cool inside furnace. Remove the next day and machine.

[dikman]

Ok if you've got a furnace.......(one thing I don't have..or need). As for Murphy's oil soap, can't get that here anyway. Fortunately I don't need to re-harden this particular die for its intended use. One bonus of using the MAPP torch is that it has a nice heat-blackened finish :smile:. I was going to polish it off but have decided I rather like it and will just wax it instead. Final product is finished and I now have a working Auto Disk powder feeder for my 44-40 cartridges.

Time to look for another project.....

[GoodOlBoy]

Be careful. Annealing might sound like a good idea, BUT the last time I tried to anneal a die to make modifications (granted it was an older lyman) the steel in it would air harden right back to where it had started and all I succeeded in doing was attracting moisture and thus rust to the die. IE all I was doing was re-tempering the metal over and over because of the type of steel it was. This is when I discovered the use of bentonite clay (cheapest you can get is SOME kitty litters are made of it) to slow the cooling. Heat the metal to non-magnetic and submerge in a tub, bucket, etc of the clay with at least three inches of it surrounding the metal on all sides. Depending on your conditions, volume of metal, etc. The metal can take from 48 to 72 hours + to fully cool.

Good luck.

GoodOlBoy