Lathe boring boolit molds

[stephenj]

One of the future projects i have in mind is lathe boring a few boolit molds

I will need all kinds of advice on this subject eveventualy .but right now i am in the planning stages

What would be a big help to start is an idea of what basic tooling to start with

Some pics of what you use and a bit on why you use it
Would be an immense help to get me started .

[RED333]

I am not a machinist, I do know how to run a lathe and a mill.
That said about the only way I see to cut a mold on a lathe is with
a boring bar, with the small hole it is gone be tough.

[country gent]

You can do it with a small boring bar for the body and grease grooves. A D reamer form could be ground for the nose. or a reamer made possibly depending on bullet desighn. Always remeber when working molds its a mirror image of what your seeing.

[deltaenterprizes]

There is a few YouTube videos showing how some have done it.
The Professor wrote a long article on how he did it.
Multi cavity molds done by manual means are hard to get consistant weight

[stephenj]

Lucky for me my ambition only extends to single cavity molds .

My slow internet conection doesnt allow me to watch many u tube vids unless i start them loading wjen i go to bed and watch them the next day .

My idea is to use a modified d bit method .
Use a tool to cut the bullet shank and grind the nose profile on a d bit to do the ogive and nose
And hopefully avoid some of the chatter from using a long d bit

But not all of my ideas have been good ones so input is very very welcome

[RED333]

You could make the cherry, mount it in the lathe head.
Mount one half on the mold on the tool rest and walk the mold half into the spinning cherry.

[cwheel]

Sure could be done with a very small boring bar single pointing the groves. Sounds like quite a challenge that way. Could make a boring tool that has the boolit form ground in and plunge directly into the side of the blocks once the bore is roughed out. This method would generate the profile and groves with the same tool. Slow going, fragile tool though. This choice might end up being somewhat easier. I just finished a copy of a Lee 6 banger on my mill with a self made cherry tool using a DRO for depth control into the side of the blocks. Waiting for cooler weather here in Nevada before I fire up the pot and test the finished product for final size and weight. Finished product sitting in front of me on the desk waiting for better casting weather. .359 was a challenge due to the small size, thinking the smaller you go, harder it gets. Things learned with this project, new and increased respect for mold makers was #1. How they do it so cheaply is beyond me. You would have to make a large run to break even with the time spent on the cherry. Thing #2 is much more respect for Lee putting a 6 banger mold out the door for less than $50. Time I have in mine I'd have to charge $300 to break even on time. Lastly, give the cherry plenty of clearance, broke the first one. Mold making is fun, not trying to discourage you in any way from giving it a go.
Chris

[Any Cal.]

I have done a trial run with a d-bit that looked good on a practice run. build the boolit you want out of O-1, then grind off a bunch of it and temper. Run it into a bore and then plunge sideways to make profile. I did mine in a solid block, so haven't played with getting the whole thing centered on the parting line.

[country gent]

Alot of you mold makers are running 3 and 4 axis cnc controlled equipment. It takes the human element out of it. a simple cutter and right program running mill rough drills cavities on location tool change to boring head or cherry and mill cuts cavities on same location. A small woodruff cutter of appropriate width could be used for driving bands and a relieved ball nose end mill for nose. Small dias make for springy tools and chatter issues. A cherry to cut a 359 dia bullet would be somewhat stabil with little flex ground and hardened correctly. Ill bet Lees machines are running full coolant,carbide cherries at 4000-5000 rpm. and set up to drop cutter in on location then do a circle pocket cutting form to size. I would bet like this they cut a cavity in under 2 mins each. All it requires is correct tooling and a 50,000 machine LOL

[W.R.Buchanan]

CG the machine is $150+,,, $50K won't buy you much in todays CNC market.

The way most outfits are doing it now is on a CNC Mill. The halves of the mould are done separately. Don't ask me how they index the halves so that the boolits come out round.

The tool is a "Cherry" that is undersized but has all the features of the end result and the mill circular interpolates the half of the pocket. Usually you would do a roughing pass with another tool and then the finish pass with your cherry.

You kind of need a tool changer mill to do this efficiently as it has to be done for every pocket.

I have been doing the machine shop thing for 30 years. I could not make a bullet mould other than something very simple, and I damn sure couldn't do it for what a decent mould costs made by someone who already knows what they are doing.

I marvel at how Eric of HP Moulds can open the driving bands of a mould cavity by .001-.002 and have it come out right the first time. This is beyond me.

Things I can't do easily I farm out.

Randy

[stephenj]

I did some reading over at cba ... i found quite a bit of helpful information .

I was able to answer a lot of questions i had rattling around in my head on tooling and operation orders ... and set up
Set up was one of my biggest concerns .

I am still a ways off from actualy being able to cut a mold .. i need to add some tooling to my meager collection .


I dont see this as an overwhelminly difficult project .
Tedius and time consuming yes in deed ... but with proper prep and a plan definatly doable

I enjoy a good challenge ... and a few failures before a success does not bother me in the least

[cwheel]

What I found to be the " Wild Card " in my 6 banger project was tool spring back. The cherry is a small highly relieved cutter. Even with roughing bore as close as I could get and still have something for the cherry to cut, I noticed on my mill DRO that not all bores cut the same material. With the DRO set to tenths of a thousands, you could actually see this by the chips produced from each of the 12 cuts. If the total bore of the cuts gets to much variance, all of the holes won't cast the same. High RPM seamed to minimize this somewhat, taking the load off the tool as much as possible. Flood with coolant. I'm sure on a CNC mill, this would be less of a factor, but on a manual, think it is. Lathe should be almost the same. Hope you have a DRO on that lathe, or use a dial indicator on the cross slide, one in half thousands. Good luck, was a fun project.
Chris

[Blanco]

I have pondered using a drill press, but not like you think.
I would use the drill press to rough the mold hole with a nice stable carbide drill.
Then convert the press into an EDM machine with a small DC power supply. It would need a flood Dielectric coolant, and a form ground electrode. This would take a lot of patience and time, but I think it could be done.
Or just find a buddy with a cnc mill and buy him his choice of adult beverage after hours.

[country gent]

We turned or milled carbonn, copper or copper tungsten electrodes for the edms at work. As long as you know the "undersize" to plug in the program its good to go. We roughed alot in before the edm to save time. I ran a charmay plunger for several years and was that machine accurate when given good numbers. A roughing and finish electrode makes a big diffrence over just one electrode.

[jmorris]

http://castboolits.gunloads.com/show...d-anyone/page2

In post #23 he says he is using a 4 axis mill.

[MBTcustom]

Yep. Been there, done that.
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[MBTcustom]

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[stephenj]

Wow .. nice work goodsteel .
Pics of nice work sure makes for insperation .
If mine turn out half that nice i will as pleased as a pig in mud .

My pocket book tells me i will be about two months away from attempting my first mold .

As i dont have a mill to make blank blocks with i think i am going to see about buying a set or two of blanks from lee .

I also need to whip up a carriage lock as well
But a plan is coming together in my mind

[jmorris]

Very nice, Tim.

[MBTcustom]

Wow .. nice work goodsteel .
Pics of nice work sure makes for insperation .
If mine turn out half that nice i will as pleased as a pig in mud .

My pocket book tells me i will be about two months away from attempting my first mold .

As i dont have a mill to make blank blocks with i think i am going to see about buying a set or two of blanks from lee .

I also need to whip up a carriage lock as well
But a plan is coming together in my mind

By far, the best thing you can invest in is a .000050 indicator. You absolutely cannot do this without it. First of all, you must align the tool with the mold, and I mean dead nuts. On longer chearies, you must make the tip of the tool point in a little in order to allow for the push of the cut, otherwise, you are going to have your front driving bands come out smaller than your rear driving bands (as luck would have it, sometimes this is a good thing, but you still need to be aware of it).
Also, you need the .00050 indicator to make it so that your can stop exactly the same depth on all the cavities. You know how we get all bent if a mold casts .001 oversize? You know how we get all hissy if our cavities don't all drop identical boolits (within .0005) out of all the cavities?
Yeah, just go ahead and divide those tolerances in half if you are lathe boring. .001=.002
I had stupid dreams of making my own boolit molds and selling them here, so I gathered up the best equipment I could, and made some pretty snazy designs. I could make the most beautiful molds on the outside (none of which are shown up yonder) but the stinkin cavities were one of the hardest things I have ever attempted to machine in my career as a toolroom machinist. There is practically nothing to indicate off of, there is no way to insure you are doing the right thing, until you take the finished mold from the lathe, and cast with it. It's only an educated guess till you do that.
Now, that said, did I do it? Well heck yes I did it! Made some really awesome molds too! But will I ever cut another? Not as long as Tom and Al are doing their thing at Accurate and NOE. Yeah, their molds cost $100 each. Let me tell you something, I would pay $100 once a month to never have to do this kind of work ever again.
I'd sooner take a job as a professional building 10 foot houses of cards! (at least there I can cheat with superglue LOL!)