need some advice, on a core swage die

[Dave18]

Ok, have read thread after thread till my eyes have gone crossed, and have not found all of what Im looking for, and I did use the search function,

got thinking about making a core swage die for my corbin 224 R die set, since reading about everyone making thier own dies on here

on the core die its self, what hardness I should try for on heat treat and then draw it back to what Rc ?, die will more than likely be out of D2 or A2 , also for heat treat we do have access to a vacume furnace at another shop


and the punches what material would you recommend ?,along with heat treat
specs,

how loose of a fit between the die and punches?

also how fine of a finish do I need to be concerned with on the bore of the core swage die? do you polish the bleed holes ?

have a friend with a well equipped shop, who said, find out the specs , and we will give it a try

[ANeat]

Dave If I recall on the hardness on the die is 50 or so. Reading thru Ted Smiths wright up on dies he just uses Stressproof for the punches with no heat treat. Basicly you want the punches softer so as not to wear out the die body.

If you use the tool steel for your punches draw it down a good bit softer than the die body.

My die from Richard corbin is .190 diameter and the punches are about .0007 smaller

You will want a good polish on the dies interior, doesent matter on the bleed hole

[ANeat]

Here is the Ted Smith info ...

http://www.castboolits.gunloads.com/...ad.php?t=52502

[Buckshot]

Core bleed die I made to produce cores for making patched 38-55 slugs. I just made the die out of 12L14. I had it. It machines like cheese and since I used Soviet Engineering I figured heat treating wasn't necessary. But then it was only for me. However the push rod WAS heat treated.

.............Buckshot

[martin]

Dave18,

A quick note on your questions as posted,

First, the heardness of the dies should be in the area of 55 Rockwell. Harder then that, the die may become brittle and softer than that it my wear more that you wish.

Second, for punches my perferred material is 41L40. Heat treat to 1550 and temper back at 400-425 over an hour or so. This will not be brittle and will wear well. You don't want punches as hard as the dies they fit into.

Third, for core forming dies, the fit has to be about 1/2 to 1 thousands under the die diameter. If they are smaller than this, the punch may not fit into the die. If they are larger than this, the cores will have fins where the lead leaks by the punch (not desirable).

Forth, when making core (squirt dies), I finish the internal die walls out to 3000 grit dimond after it has been heat treated. This produces a mirror finish and helps with the core extraction.

Fifth, the shish die bleed holes for the displaced lead do not have to be anything special. I usually drill and ream the holes but I doubt that the reaming is necessary.

Good luck with your dies and let us know how they trun out.

Martin

[Zbench]

Martin,

How exactly do you finish the walls with diamond? Is it some form of paste that you use and lap with the punch? How much "allowance" do you leave to lap from the machined size?

For instance, if you wanted a cavity of exactly .510, would you bore to .509, treat and then lap? Or something else? Inquiring minds want to know.

Pete

[hardcase54]

With my .224 point form die. I reamed to .220, then made a lead lap . Coated with diamond paste and started lapping. Stop swage a lead slug and "mike", took about three tries but my die came out .2245 as close as I can measure. But who knows may be a better way. Works for me.

[Zbench]

Thanks Hardcase. The reason I ask is I have a lathe and can turn to pretty close tolerances. Making a swage die on the surface does not seem to be hard from a turning and reaming perspective, but the finishing is another story.

New question, are 6S ogive reamers available in various caliber diameters? If not, what did you use to form the point on your point form die?

Pete

Pete

[ANeat]

New question, are 6S ogive reamers available in various caliber diameters? If not, what did you use to form the point on your point form die?

Pete

Pete You will need to make your own cutter. Either a D reamer or some other shaped cutter.

Here is how one member did his.

http://www.castboolits.gunloads.com/...&postcount=145

[hardcase54]

That is correct. The first one I made I used a D reamer( ground from a drill blank.) The last two I used KTN's reamer setup. It was trickey the first time but the second was easy. ( I broke my first reamer, too hard)

[martin]

Zbench,
Diamond lapping compound can be obtained from a variety of machine tool suppliers including MSC and my favorite Enco. It is relatively expensive in small quantities (sold is plastic syringes) but for die work it is great to work with. The grits available range from 120 grit to 100,000 grit.

I have used both aluminum oxide and diamond lapping compound (both are in paste form premixed with an oil lubricant) and have found that the aluminum oxide is ok but breaks down much quicker than the diamond. In other words, if I use 320 grit aluminum oxide for more than say 10 minutes of lapping, it will have the consistency of 600 grit when the particles break down whereas if I use 320 diamond, it will maintain 320 grit for hours.

In regards to allowance between lap and machined size, I usually taper the tip of the lap so that it fits into the hole and then make the body of the lap the size of the current hole I am lapping or a little smaller (1/2 thousands). Any larger than this and the lap will bind in the hole. The hole that is being lapped will end up about a thousands larger than the lap depending on the grit of the lapping compound. Note that my method takes multiple laps to get the correct sized hole in a squirt die. Also note that after lapping the hole, itmust be thoroughly cleaned before either being measured or fitting a finished punch.

Your question about wanting a cavity of .510, in my opinion, I would not bore to .509 because the machining marks would not allow you to finish out to .510. These machining marks are likely .002 or more and remember this is .002 per side which is .004 total. A much better way of doing this would be to drill or bore and then ream to .002 or .003 under finished dimension. Then you would heat treat/temper back to the desired hardness and lap to finished dimension. Note that dies can an do change dimension when they are heat treated thus the .002 to .003 margin of error before heat treatment.

I have leaned along the way to make dies in pairs. About half the time I mess up one before getting a good one. Remember that it is easy to take material off but very difficult to put it back on. If both dies come out good, you always have a spare.

Whatever you do, please let us know how things are progressing for you.

Thank You,
Martin

[Zbench]

Martin and others,

I sincerely appreciate the advice and counsel. I love swaging, more than casting, but to buy dies for all the calibers I'd like to swage for would cost a small fortune. With this idea in mind, and considering I have a CNC Mill and an engine lathe, I bet I could get some acceptable dies and stop sending money to Corbin!

I'm sure I'll ask more questions when I get to making some chips.

Pete

[Dave18]

thought I would thank everyone for thier replies,

so far just got the die started, will let ya know when I get things together,

[Zbench]

First, the heardness of the dies should be in the area of 55 Rockwell. Harder then that, the die may become brittle and softer than that it my wear more that you wish.

Martin

I saw this and don't dispute the logic or the thought behind it, but thought I would measure some of Dave Corbin's dies to see what the hardness was.

I tested a handful of the dies I have, and they are much harder than 55C. The three I tested all came out to be 64-65 C which is harder than a good woodworking chisel and approaching file hardness.

I'm sure 55C would work just fine, but figured since Dave is in the business, there must be some thought behind his hardness values, and thought I would post it here since I have a calibrated tester.

The dies I tested were all "S" dies. Core Swage, Point Form and Core seating.

Regards,

Pete

[martin]

Zbench,
Wow, that is interesting that Dave makes these dies so hard. If I remember correctly, files are usually in the 60 to 61 Rockwell C range and they snap fairly easily.

In the end result, it is up to the die maker how hard he wants his dies to be when he draws the dies back. The die hardness is really a personal choice.

I have heard/seen pictures of dies that have split during operation and generally presumed that either the die was too hard or the user was applying too much pressure. I don’t think that a core forming die should have very high pressures since they have bleed holes this would mitigate the pressure to a large extent. For the dies that I have made, I have more or less standardized on Rockwell 55C but I am also not real concerned with wearing out a die since it is unlikely that my dies will see more than 20K in my lifetime.

Maybe you could ask Dave his thoughts on the subject and post them.
Thank You,
Martin

[Daywalker]

Just to add to the discussion of hardness, CH4D dies are hardened to 60 as well.... Dave has told me this in an email when he and I were talking about his dies that he makes that BT offers the internals for...

[Dave18]

my die gets heat treated this weekend, going for a rc55 hardness,

step by step