Thread: Paper patch bullet mold--improvised D bit?

I'm thinking of taking an otherwise ruined 30 caliber Lee aluminum mold and repurposing it as a .352 straight sided bullet for paper patching in the .35 Whelen. I've seen some guys doing similar over on the Cast Boolets website by making their own D bits. I was wondering if a reground wood boring spade bit could be used, given that I would be cutting soft aluminum, of if the thin flat profile would cause too much chatter?

I am not sure how a flat spade bit would be a D bit, unless the spade bit is really thick and you are grinding away a bunch of it. Otherwise how would it be a "D" shape?

I would think it would be a huge pain in the ass to try and grind that type of a bit. Why not just take a standard twist bit that is the right diameter and grind on the shank end (the part that you would normally chuck up)? You could even grind the profile that you want for the bullet tip.

Many people have a bunch more experience with making D bit reamers than I do and will talk about grinding in relief and other things and I am sure they are right. But, I have had great luck just turning my bit to the profile that I want and milling off slightly less than half the diameter (I try to leave between 0.005-0.008" more than half) then half assed heat treat with a torch and can of oil. I don't grind any relief onto the cutter, just stone the cutting edge until it is nice and sharp and cut away, great surface finish holes (the correct size) have always resulted with nice large curls coming from the cutting edge.

I am using O1 round stock for all of my D-bits and I leave them glass hard or heat the oil up to ~250F for my tempering. I have not had one shatter or chip yet.

I am holding the D-bit in the tail stock and turning the work very slow, ~5 rpm with lots of cutting oil and frequent chip cleaning.

If you are cutting into aluminum and only doing it once you can probably get away with some pretty marginal heat treatment (like a quick case hardening on mild steel) or no heat treatment at all.

Good advice on the D-bit. It needs be no more complicated than described. The D shape has a function in that it keeps the cutting forces on center and straight. A spade bit would create all sorts of problems if used to open up an existing mold. It might function OK for making a mold from solid blocks, but for myself, I would choose a D-bit for that as well.

Yes I'll third that on the D bits. Once you've made one you'll never look back. I use O1 as well but I temper in my convection oven/microwave to 450-470 for 30 minutes. (usually long enough to have lunch

You are heating steel in a MICROWAVE??? How is that possible?? Are you making X-rays in the process? Maybe the convection/microwave is different from the ordinary microwaves we have here.

I have made very nice aluminum bullet molds by taking a 1/4" square bar of W1,and filing the profile of the bullet I want to make on 1 side of it,with relief cuts below the profile so it will cut. I put in grease rings also. Then I drill out the mold block to the required depth using the tool I made,and draw the tool sideways,checking the diameter until I get it right. Works fine.

Of course,I hardened the cutter and drew it to a dark straw first.

Lol Convection= Hot air

Actually you can melt metals in a microwave oven, maybe even cast iron

Microwave melting of metals

You are heating steel in a MICROWAVE??? How is that possible?? Are you making X-rays in the process? Maybe the convection/microwave is different from the ordinary microwaves we have here.

Yes,
Most small foundries now use a microwave crucible, and they're the cat's meow. There's one where I work in Esquimalt dockyard, and I couldn't believe it when I first saw it. It's quiet and clean.

I am sure I will catch much abuse from the following, but I am going to say it anyways. I think it is highly optimistic and some what delusional when at home hobby level heat treaters try to temper in toaster ovens, home ovens or with a torch by looking at the colors to identify color change.

I think there is no time for the temperature to equalize in a large tool that often has a thin cutting edge (so the thicker body of the tool is glass hard and the cutting edge is the softer tempered part, the opposite of how I want things). I just have not seen anyway to really "soak" the tool at the temperature that I want to get a even temper and not form mixed structures, even in an oven. The element cycles on and off, things are not even, and air is a pretty marginal conductor for heat anyways.

I know a bunch of people use these methods and I have as well, it works plenty well. But if you have the choice, I would highly recommend using a bath of some sort to temper in (if you get some of the fancy heat treating salts you can even make a bath to heat you item up for the initial quench, good if you are heat treating something like a long knife/sword and you don't want to burn the edge off before it is all up to temp.)

I will use a hot oil bath (normally old cooking oil, the fumes smell like whatever you fried last and I don't feel like the fumes are going to kill me if it gets too hot) just be ready for the very real possibility of a fire. A real metal lid that fits tightly and a cool head to quickly put the lid on are a must. Preferably do this outside on a hot plate, then your whole shop won't smell like a fish fry.

If I need to get things hotter than the oil can safely go I use a pot of pewter (lead free, gets slushy melted ~380F) that I keep around for just such uses. It melts even lower than lead. If you don't mind having molten lead around your shop I think tin/lead eutectic is ~370F. This give a good overlap in temperatures for tempering since most fry oils can get to at least that temperature before smoking.

Buy using these baths and a good thermocouple or thermometer I can let my tool "soak" for a long time at exactly the temp that I want to make sure every part of it is fully up the temper temperature.

Honestly I think this is even easier than polishing the tool and trying to read the colors when you heat with a torch for tempering. You can go straight from the initial quench to the tempering bath and be done.

I had a book at work which I cannot remember the title of,but it was the best book on tempering steels I ever had. He recommended using a toaster oven. I use one also,but only with an accurate thermometer with a long probe from Brownell's inserted into it from the back.

This way I can set and maintain the exact temperature in the toaster oven for soaking of hardened steel parts.
For hardening I use a 22" deep Paragon electric furnace with thermocouple.

The reason for this is that to get the most out of your steel,you need to insert it in a pre heated oven set to the tempering temperature,as soon as the part cools enough that you can barely handle it (about 130º)

At work we eventually got another Paragon furnace to temper with,but they are pretty expensive,and take up space which I need.

The author of the book was a professional toolmaker,as I was,now retired.

I agree with not trying to rely upon colors,as different steels will not be the same temp. at the same color. It is helpful if a person just uses the same tool steels repeatedly since experience will accumulate in how to get the best results from that steel.

I'm not saying that your methods are not correct,I just do it differently. IF I were making something critical,like a gun receiver, I might resort to soaking in a bath to temper it,but I'd have to round up the stuff to do it that way.

I think it is highly optimistic and some what delusional when at home hobby level heat treaters try to temper in toaster ovens, home ovens or with a torch by looking at the colors to identify color change.

My first question is why do people feel a need to make ridiculous and derogatory statements.

Firstly I think you'll find that if you do a little more research that superheated air ie convection is THE preferred method for tempering and heat treating when things are really sensitive and critical

Secondly I'm not sure what massive body thin edge tool your talking about but we're discussing a D bit the size of your pinky that is ideally tempered at 470deg F for 30 minutes.

Thirdly I'm not sure if your aware but we made it through the industrial revolution and a few world wars without the use of a Paragon, a PLC, thermocouples, or "some sort of Bath"

And I think you'll find find that the Japanese have been hardening and tempering things to exquisite refinement for about 1500 years prior to that....were they delusional hobbyists as well?

Originally Posted by RifledAir

My first question is why do people feel a need to make ridiculous and derogatory statements.

Firstly I think you'll find that if you do a little more research that superheated air ie convection is THE preferred method for tempering and heat treating when things are really sensitive and critical

Secondly I'm not sure what massive body thin edge tool your talking about but we're discussing a D bit the size of your pinky that is ideally tempered at 470deg F for 30 minutes.

Thirdly I'm not sure if your aware but we made it through the industrial revolution and a few world wars without the use of a Paragon, a PLC, thermocouples, or "some sort of Bath"

And I think you'll find find that the Japanese have been hardening and tempering things to exquisite refinement for about 1500 years prior to that....were they delusional hobbyists as well?

Awesome reply, but I have to suggest that those Samurai guys were probably sitting there beating steal muttering "damn I wish somebody would hurry up an invent a thermocouple and take the guess work out of this... so we could make better swords than our enemies..." I mean if they would have had the stuff they would have used it, but still used the bodies of live prisoners to test the results.

The truth of the matter,though years ago I too made plenty of tools,heat treating them without any equipment other than a torch,is this: There is only a 25º "window" of temperature that will give you the MOST benefit from your tool steel. True,many thousands of small tools are made in small shops every year,just like I used to do(and STILL do for a quick tap or other small tool). But,if you are making a die worth $250,000.00,it becomes imperative to get as much use out of it as possible. Or,if you are making an expensive,fine knife,you also want the heat treatment to be as good as possible.

The Japanese smiths making those swords did the same thing over and over again for decades,actually using steel made from the worst ore(sand iron). Their experience and vast training paid off in their specialized field. Most small shop guys don't have that huge amount of experience,though. I used simple methods for many years,but I do like my Paragon furnace.

I absolutely and utterly agree with everything you have said.

I guess the real point is that at one time being able to make a D bit or a tap in the shop, on the fly, quickly and accurately was a required skill. Is technology causing us to lose sight of basic skill sets?

Originally Posted by Headcase

Awesome reply, but I have to suggest that those Samurai guys were probably sitting there beating steal muttering "damn I wish somebody would hurry up an invent a thermocouple and take the guess work out of this... so we could make better swords than our enemies..." I mean if they would have had the stuff they would have used it, but still used the bodies of live prisoners to test the results.

The Japanese actually have some of the finest manufacturing equipment and skilled people people on the face of this rock. And today, if you have $15,000.00 you can buy a brand new sword, made by the same families that were making swords hundreds of years ago. And wouldn't you know it, they still don't use CNCs, space age heat treatment furnaces, modern steel or any of the modern contrivances found in Japans many high tech factories. Not even a temperature controlled toaster oven for gods sake! And they are just as good as the ones made hundreds of years ago. Maybe even a bit better. They have had more time to practice. LMAO ROFF

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I agree with you,spearchucker. However,the operative word here is practice. It is certainly true that if you devote a lifetime to doing one thing,and do have the potential talent to begin with,you can build a great product. On the other hand,how many of you would toss a "pinch" of powder into shells with no measurement?

Best to avoid either extreme,I think,and develop basic skills as I have certainly done,but use good technology too,if you can afford it,when necessary to get the very best results.

I rely upon hand tool skills much more than most craftsmen. Especially as I was working in a museum most of my career,daily using files,wooden planes,and many tools I made.

Thanks for the comments. It occurs to me from reading post #5 that I could probably do all I need to do with a 1/4 HSS tool bit ground to nose profile. I could drill a .300 or thereabouts hole and then profile the cavity with the shaped bit.

Right? And such a bit could be used to make many different diameter and length cavities with similarly proportioned nose profiles.

Originally Posted by speerchucker30x3

Not even a temperature controlled toaster oven for gods sake! And they are just as good as the ones made hundreds of years ago. Maybe even a bit better. They have had more time to practice. LMAO ROFF

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ROFLMAO



The nice thing about the D bit is you can see and easily measure the external profile and that's exactly what your going to get on the internal hole.

On the other hand,how many of you would toss a "pinch" of powder into shells with no measurement?

Well, I would hope that while you were practicing your pinching that you got good fast before you blew off all of your pinching fingers. Otherwise you might be forced to go out and buy a scale. On the other hand I have never had a piece of steel blow up in my face while hitting it with a hammer so its probably not a good analogy. But I like the way you think. In a morbid kinda way.

I like the way you think too,spearchucker. My thought is we all rely upon technology to various degrees(like the scale). Not good to totally deny the use of it.