Building casting molds

[rossrods]

Hello guys. Just curious as to how bullet casting/ molding process works? My background is in fishing mold making industry. There's actually about .002 of a inch one might could be off and it really will not be noticeable with a fishing mold, Other than flatness between plates of course. The production molds that you guys buy are they medical industry held tolerance.(.0005) accuracy. I do not have much knowledge about casting. After you guys cast, does one always run the cast thru a sizer die? This is one of my proto/play molds, would this style of mold be useable in bullet casting. Of course it would be a bullet profile. I know one needs a spur plate and mold to be made of steel? Would aluminum work? I've never attempted a bullet mold because I assumed that precision had to be held down to .0005.

[salty dog]

Yes, tolerances would be in the .0005 range for diameter. For instance, custom mold makers offer the choice of .357, .358, or .359 for the same caliber, so it would have to be at least .0005 inches to get that. Most, but not all, bullets would be run through a sizer.

[bangerjim]

There is casting fishing lures.......and then there is making precision boolit molds.

The hardest part is making the cherry to cut the mold cavities. As you know a boolit has lube grooves that must be cut along with the ogive/nose cut. Making that cutting tool ACCURATELY is 80% of the work. And accuracy of 0.0005 is definitely important. But so is REPEATABILITY! And they MUST be of a mirror finish in the cavities. You have to make the same cavity time after time, mold after mold, if you are contemplating getting into the mold monger business.

I buy all my molds even though I have a full machine shop and skills to make all the parts and tools. Just too much time involved for very little result........in my book.

Aluminum is the standard material for multi cavity boolit molds, although there are steel and brass premium ones. The pros and cons of these materials have been covered many times in previous threads.

bangerjim

[Yodogsandman]

Blank molds are available from Lee for about $30.00/2 cavity. I don't know if they offer the 6 cavity blank, though.

[bangerjim]

You can buy a complete Lee factory-made 2 banger mold ready to cast for around $17 on line.

The mold blank is mabe 10% of the overall "task" of making a good successful mold.

I can hog out a 6 banger mold blank in a short time but precision aligning/drilling/boring the cavities is the big thing....ONCE you have made the precision cherry. Accuracy hinges around that custom cutting tool.

It all hinges on your personal needs, value of your time, and tooling/skills you have.

Good luck if you decide to stick your toe into the mold-making pond. Let us know.

banger

[rossrods]

I agree. Way beyond my scope of tolerance's and my choice of milling capabilities. There's something's that's just best left to those who have the knowledge and correct tooling/milling. Thanks

[Yodogsandman]

I misunderstood how you wanted to save time building your custom mold.

When I was twenty years old, I made a .58 cal. maxi ball mold. Thompson Center Arms made maxi ball molds for a bunch of other calibers but, none for the .58. My mold shot just OK, better than I had but, I didn't take into account that the lube grooves needed to be angled or rounded. I made the grooves straight sided. I had a heck of a time trying to mold with pure lead without voids. I added Sn and got no better bullets. I went back to my dad's Lyman mini ball mold. So, I understand the task and hope you have much better results.

[Any Cal.]

There is a lot that goes into a good mold, but you may be able to make a crude one without too much trouble. A single cavity that is within a couple thousandths would get you in the ball park. I have sized down heavy .40 boolits to .370 for paper patching, though I can't remember if I ever shot them. Sometimes it would be nice just to try out an idea without spending $100 plus a few week wait on a mold, you might be able to get that from the looks of your fishing mold.

[rossrods]

On this note then, will a lee lube sizer die swage up, if your a few thousandths under cut, or draw down if your a few thousandths over. I don't own a lee sizing die so just thought I would ask the question. It makes sense that it can't swage up because there's no punch to cause pressure for your cast to expand. Ok help me here. if you cast a lead projectile, then you copper plate this, there's no way to accurately control the plating down to .0005. The bullets such as berry's, aren't they swaged? Just curious because I have no idea. Thanks Rick

[country gent]

Most sizers will only size down in size. Sizing up would require a dies similar to a swaging die that would produce alot of pressure over the form of the bullet to make it flow bigger.

[big bore 99]

Having been a tool and die maker all my life (48yrs) and had my own shop for over 20 years, I can say it just isn't worth it. Unless of course there is an odd design or certain size unavailable. I have a few Lyman and a bunch of Lee molds here and they are the way to go. I worked in the injection mold industry where tolerances are sometimes .0001. I've made a few for myself, purely for the satisfaction of doing it. Round balls are the easiest. I rough them out with a ball end mill staying away a few thou.,and then use the right size ball bearing in a hydraulic press to press them together (hobbing) then dust the halves off with a surface grinder and lightly vent.

[rossrods]

Ya big bore. My cnc milling capabilities aren't within those tolerances. Neither is my machining skills. It take's years of experience and many hours to get tolerances that tight. I was more interested in being able to get close, then allow a set of dies to finish things out. Just wondering if it could be done this way. It would have to be a simple bullet design with nothing special to it. I had one individual come to me inquiring about building bullet molds. I ran as fast from this as I could. It was some years back, not to say things have changed that much. Having swaging presses and dies has opened my ideas to other ideas. Case in point I'm going to build a 7.62x25 1911. It shoots a .308 80grn-110grn bullet. You can purchase a .308 Mauser style bullet, or purchase a .32 calibre and run thru a lee .308 sizing die and draw down to .308. Why couldn't I build a mold as close as I could get to, which might be +.0015 of actual needed dims. Then run thru same sizing die.
Another question when you guys cast, then epoxy coat your bullets. Are they ran thru a sizing die to bring down to correct dimensions? I know there's stickies, it's easier to ask questions(should of done that in high school lol) than to spend hours researching.
Something else from the machining experts it would be nice to know how to build a mold from a cherry. There's not much info into this. I've researched this very topic and spoke with custom tool makers. There's probably some that have no idea what a cherry is. They wanted 45 dollars per cherry at a minimum of 10 end mills. So basically $450.00 for 10 cherry's with tolerances down to .0005. That's a good bit of cash and could buy a lot of bullets, or buy a mold already made with a good bit of lead. if you know what I mean. I'm more than likely not going to do this. Just wanted the knowledge.

[big bore 99]

Don't get me wrong, there is considerable satisfaction from dropping the first few from a mold you made. To save some bucks or as a business venture, I, in my opinion, just don't consider it worthwhile. I've made a few hollow base with grease groove styles and it was a lot of fun. Lot of work too. with what's on the market these days, it's easy to make tooling to resize or bump up sizes and then resize thru a homemade die.

[bangerjim]

I powder coat EVERYTHING these days. I size AFTER casting and AFTER coating. That 1) eliminates any out-layers due to large size, and 2) guarantees I am loading the exact same thing EVERY time.

There are videos on the net showing how to calculate and cut ogives on a lathe. If I were making a cutter to make a very special mold or two, I would use OH drill rod, turned/ground to the size and shape and relived to cut, on the lathe and mill. Then harden and temper it appropriately. That would easily cut a few Al mold cavities or mabe brass......but not many of steel accurately!

The time involved, for me, is just not worth it. There so many styles, types, and variations of molds on the commercial market today, I have yet to feel the urge to waste a bunch of my time making a custom mold.

I have a policy: if I can buy it commercially, I will, and not waste copious amounts of time making something someone else makes in bulk.

There is.....to a finite point......a feeling of warm fuzzies making something yourself. Again, you must balance the value of your time (life IS short!) vs. the product you will have. The Law of Diminishing Returns comes into play here.

bangerjim

[big bore 99]

Exactly... at my age, I'd rather spend time shooting or rebuilding a rifle than making molds. The cherries I did make were of W-1 toolsteel. It's water quenched and can get harder than O-1. With very little draw if any. I recently broke down my business and sold most everything. Had 5 lathes,4 mills, tig, mig, stick, and torches,a surface grinder and numerous drill presses and tapping machines. It hurt but needed the money and didn't figure I'd use them much in retirement. Now I'm working with a hand drill and files. Ha!

[rossrods]

Yes sir I tried the business venture 2008 worst time since depression. Got a business loan,spent 20K in software, personnel money. Bought a used cnc mill with only 200 hours. Did this with only one costumer. Stupid me!! Had a gentlemen I was introduced to who was in retirement making molds for tapco and asked me to help him with cad and cams and he would return favor using his cnc mills to cut molds. The sales person for the cnc company, who was introducing me to him so I could see a home shop in action with the mill I wanted, he the salesman almost had a heart attack thinking he was going to loose the sale of the mill. Well the gentlemen new exactly what I should've done, which was to do as he suggested worst mistake of my life. I did learn a good lesson. Needless to say there are those cut out for business and those who better work for those who are cut out for such. Don't cut yourself short my friend it's a major accomplishment to of been in business and making money at it. There's such great pressures from bills, to keeping employes busy, and making a profit so your business can strive. No easy task at all. Your going to miss the chips.
It's in your blood, after using your hands all these years and being good at such are you going to be able to stay retired? Medical health forced me into retirement hardest thing in your life to do is to leave what you know best. Sorry to hear about liquidating. I hope you were able to do ok with it. I'm more than sure your very accomplished with a drill press and can do more than most with a cnc LOL. I do things as a hobby pending my health which changes from hour to hour. I'm saving with retirement income to purchase a home gun smith lathe to continue my quest to stay busy. Which in turn keeps me healthy.

[big bore 99]

Thanks for the compliment. I'd like to think I was ok with the trade instead of fakin' it all those years. The last few years were the worst. A lot of the time I worked for a job shop full time and did my business on the side. Had some good guys working with me and hated to let them go, but couldn't keep them on. The smell of cutting oil does get in your blood and do miss it, but health issues have gotten me too. Had some experience with cad/cam. Ran 2 wire edms for awhile. It was a learning experience and a good trade. Always had lots of overtime when working for someone. Come to think of it, I worked lots of hours when in business too. Just never got paid for it... Ha