phillips head anyone ?

[taco650]

Is there a thread pitch that is "more course" than 5/16x18 that still fits the boolit body diameter you want?

[oldpara]

Is there a thread pitch that is "more course" than 5/16x18 that still fits the boolit body diameter you want?

That's about as coarse as it gets with that diameter, even a metric 8mm is about the same.
I could model up my own thread pitch, a 14 or 10 but wouldn't it be neat to grab a bunch of bullets out of a box or bag and be able to "freshen" them up by just running a nut over the threads and make them all sharp and shiney again

[taco650]

That's about as coarse as it gets with that diameter, even a metric 8mm is about the same.
I could model up my own thread pitch, a 14 or 10 but wouldn't it be neat to grab a bunch of bullets out of a box or bag and be able to "freshen" them up by just running a nut over the threads and make them all sharp and shiney again

Yes that would be a nice but I was just trying to think of a way to reduce the chances of them sticking in the mold.

[oldpara]

Yes that would be a nice but I was just trying to think of a way to reduce the chances of them sticking in the mold.

I know you were.
And the cleanup with a nut was just tongue in cheek stuff.
I really just don't know what could be expected using a threaded section in a mold.
I suspect, given my lack of common sense and control I will find out at some point.

[azrednek]

Even though the Boolits are a novelty. I bet there would be enough interest to put a group buy together. Anybody out there with a CNC machine and the skills looking to make some bucks should consider it.

[pls1911]

True Industrial Art

[oldpara]

The more I look at this thing the more I wonder if I'd get the mold halves apart full of lead.
That's a threaded hole, don't they call them fasteners for a reason ?
I wouldn't want to have to screw them out of the mold. That would put a cramp in production.
Anyway, I thought about making it a nose pour, drilling/tapping part way into the mold then milling the rest.
Well problem is I need an F drill (.257) and the nose has a .190dia flat, so no go there.
Plus after tapping I've removed metal where I wanted the nose section to be.
But when staring at it some more I decided that I could mill it base pour.
First I'd vise up the halves in the bridgport, find the middle, drill/tap short of full length.
Then set the blocks in the mill and mill the body (hoping everything cleans up ok).
5/16-18 thread and a .313-.314 body dia. Thats cutting it close, no pun intended.
Then mill/blend the nose section in and call it done.

All this said, I'm not at all sure I'll even attempt it but it's sure getting more tempting all the time.
The company I work for was bought out and the new security is "ANAL"
Xray machines, walk thru metal detectors, hand scanning..............
I feel like I'm at the airport every dang day..


Here was my thoughts for nose pour. You can see the tap has removed the metal I want to mill for the nose.


then heres the drill/tap from the base, mill cleanup, seperate mill the nose deal.


Oh, and heres the phillips GC bullets

Here I am replying to/adding to my own post.
Anyway, I was in the cellar thinking that if I talk with the security people, explain what I want to do, show them the materials I'll be using (scrap brass mold blocks) etc, it may ease their anxiety and they might be inclined to let me go for it.
They're regular guys, they just have a certain responsibility to the corporation.
If that works out I have a need for your input on this threaded boolit.

Normally I would create the mold block on screen subtract the part from the mold half and just mirror the block for the other half, BUT, this being a threaded section I'm not sure that mirroring is correct given the pitch/angle of the threads.
I think I'm going to have to subtract the part from the block as you see it in the image for one half of the mold then subtract the part again from....
In other words, I would take two mold blocks, put one on top of the other with the part sandwiched between them.
I would then subtract the part from the bottom mold half for one half of the mold and the subtract the part again from the top mold half to create the other half of the mold.
Is that making sense ? You know "clear as mud ".

If these were concentric (no angle/pitch) circles mirroring would be OK but their on some angle spiraling down......
I'm just thinking I truely need a seperate left and right half.
Am I over thinking the thing ?

[SlippShodd]

I'm just thinking I truely need a seperate left and right half.
Am I over thinking the thing ?

Overthinking stuff like this is MY job, and no, I don't think you are; the two halves have to be different to accomodate the spiral. What I don't know anything about is modeling software and how big a PITA that would be to design and mate those two different halves perfectly.

mike

[oldpara]

OK, I think I've answered my question, but you take a look too.

Heres a simple mirror, one block superimposed over another.


It looks fine



Hers the sperate subtract from to and bottom.



It "looks" like a simple mirroring for left and right halves will do the job. Yes/No ?

[SlippShodd]

It looks fine
It "looks" like a simple mirroring for left and right halves will do the job. Yes/No ?

LOL! I'm glad it looks "simple" to somebody. But, yes, it "looks" right, or for all intents and purposes, right enough. I'd be tooling up and "wasting" a couple pieces of material at this point. A look around my lathes will drum up enough examples of spare parts for stuff what ain't been invented yet.

mike

[oldpara]

LOL! I'm glad it looks "simple" to somebody. But, yes, it "looks" right, or for all intents and purposes, right enough. I'd be tooling up and "wasting" a couple pieces of material at this point. A look around my lathes will drum up enough examples of spare parts for stuff what ain't been invented yet.

mike

I'll tell you, sometimes even with the software and sometimes because of the software you wind up wondering ***.
The only way to really see what's going on is to just cut something in wax and actually "LOOK" at it.
You would think that after 30yrs of doing this stuff I'd have a solid handle on visualization but alas I'm still stupid.
But if it was absolutely, straight forward simple it wouldn't hold our intrest for long.
Simple is boring, I guess that's why crossword puzzles are popular.

[Box13]

If you had 2 helical threads wouldnt each half be identical?...Robin

[ncbearman]

How bout this one from the Firearms Museum. I have a colt and would love to make the coffin that holds the vampire slayer.

Attachment 60852

[oldpara]

If you had 2 helical threads wouldnt each half be identical?...Robin

Yes, the threads are the same cross sectionally, they just don't align properly by simply mirroring.
I got to thinking about it again, still..
Mirror won't cut it. I need to subtract from both halves, top and bottom.
I believe these images make it clear.
Looking down on the part laying flat on a table with the part perpendicular to the parting line the threads look fine.
But rotate the part 90' with the parting line parallel to the halves and you can see the threads are all wrong.
They don't spiral down properly.





So if everything goes well with "Goombas" I'll re-model the part in the other software so it will be less troublesome programming and maybe cut some wax first to confirm.

[pls1911]

Ok, so I'm an old gear head and engineer, but was never trained as a machinest.... I am simply in awe of your energetic creativity. I Love it....and I really appreciate you guys sharing with the rest us.

[oldpara]

Ok, so I'm an old gear head and engineer, but was never trained as a machinest.... I am simply in awe of your energetic creativity. I Love it....and I really appreciate you guys sharing with the rest us.

I'm compelled and obsessed to do this stuff, it's addictive and absorbing and so much, can I say fun?
I truely enjoy sharing this with everyone and getting the feedback.
I am by no means an expert when it comes to lead bullets, the alloys, and all the various variables involved, but sharing this and learning from all of you is just so pleasureable.
Again, this forum and all of you are such a gold mine of knowledge, I learn something new everytime I am invloved with you good people.
We have a common, enduring love for this sport. It is an incredibly interesting hobby.

[oldpara]

I finally re-modeled the piece in the other software.
It's all programmed and ready to cut.
I'm going to try it in wax first as I said before so perhaps tomorrow I'll get to see if the toolpath is going to be as I hope.
I needed to change the threads a little, I am concerned about releasing the part from the mold.
The thread pitch is now very non standard and I increased the width of the root area.
Before the change it was a true 5/16-18, with a .312 dia. OD. Now it is .302 dia. OD (for my 7.7 Jap) and probably a 16. So a .302-16. with .314 body dia.
Still, its a threaded part, has the look.



Heres a ratty screen capture of the programming process.



If the toolpath looks OK, I'll scrounge around for some scrap brass blocks, get them prettied up, get everything ready and approach the security guys and try to get thier blessing.
We'll see.

[jmorris]

Seems like your not going to make a ton of them. Cast the bullet then cut the threads.

[oldpara]

JMORRIS, That is definately an option although I tried running a die over a 311284 once before.
Maybe it's just me, but I didn't have much luck, the lead is so soft, it looked pretty bad and it was a pain trying to hole the bullet.
Besides, part of the fun is seeing if a mold can be made and if (a big if) it produces a viable, decent looking projectile even if only of novelty value.

I got the go ahead from the security boys, and cleared it with the bean counters and hand wringers.
I had all my materials, programs, trial cuts, and ducks in a row.
So as of about 3pm I set up the mill, put a block in and started cutting one half of the mold.
When I go in tomorrow morning that half will be cut and I'll start the other half. Hopefully by Thursday I'll have it pinned and finished.

Being reasonably optimistic, and having just set a precedent by going through new corporate channels with this one,
I modeled and programmed one for the 45 ACP this evening that I may try cutting some reasonable time after this one.

It's should cast about 190gr, .453-.454 dia.






If I have a right hand twist in the pistol and a left hand thread on the bullet, is this thing just going to bounce off everything I shoot at ?

[whelenfan]

They are truly awesome!