Making a custom mold advise needed
I have half of this figured out. My idea is for a simple to produce mold for testing different shapes and weights of pellet. My tools are limited to mostly hand tools however a surprising lot can be accomplished given time, trial and error, and lots of stopping for measurements. I’m not making them by the hundred for target practice or anything. My plan is to trial and error my way through different concepts and hone craftsmanship in the process.
I can polish the sides of two pieces of aluminum bar stock to near mirror and grind the top flat so they match seamlessly. Instead of hinging the mold I will hold the two halves together with pins and clamps. I could drill it out easily enough and counter sinking it will make a simple conical skirt. I won’t attempt hollowing the skirt at first and could try gas checks or maybe paper patch. Where I am stuck is creating the head and gas checks. For the head of the pellet I have considered putting a metal sleeve down into the mold to protect it with the bit chucked into a Dremel suspended in a crummy drill press like device. Then rotate the entire mold along the bench as the burr head cuts and use the sleeve as a sort of fence to limit it’s cutting depth. Measure, adjust, replace with different size sleeve, repeat until desired result. A modified wire nail could be used similarly to cut gas checks into aluminum. I would be glad to hear any improvements to this.
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Jerry just can’t help himself. He cares so much he just had to say!
A good point Jerry. Often times, I find myself switching back and forth between the desired “end result”, the available tooling, and my own “less than perfect” skills. Often compromises in one area force changes in others….or so I’ve found. 🙂
But insofar as tooling goes…perhaps this might be of aid?
http://www.groz-tools.com/index.cfm?MainDisplay=Products&SubDisplay=ProductDetails&ProductID=110
Not sure if it’s up to the task, but I’m thinking it’s better than a “regular” vice.
Al
Gippeto,
The guy can spend his time and money anywhere he likes as far as I’m concerned. I think he ought to be working on tooling to overcome the challenges Walt pointed out instead of deciding his slug design.
That’s pretty interesting Banana.
but hell its all been done before so its laid out for review, the twist for calibers and bullet weights, i have paid attention to mostly the twist for the .22 cb cap compared to the twist for long rifle for example. the cb cap and short for that matter specific rifles were brought out with 1-22 twist to 1-20 twist barrels for 29 grain .22 bullets ,, 1-16 for 40 grain 22 long rifle bullets .
The 22 hornet is a1-14 to 1-16 for 40 to 45 grain bullets.
222 1-14 for 50 grain or so bullet.
223 1-12 to 1-9 for 55 to 65, and 1-8 for the heavies , 75 grain’s.
So why does the air force work so well with 1-16 twist. ?????
I have had good luck with both the Eugen’s, in my condor , i have the 32 g. right at 1000 fps , with 1/2” or better at 50 yards.
My thoughts on the making the mold in the garage, how about a reamer.and some aluminum bar stock. if a guy could grind down a reamer to just the right size. then clamp the aluminum block around the reamer while cutting.????????
Drill some index holes and pins for the aluminum block, have blocks in vice. ???
Sorry AG, that mold won’t work. It is the type designed for fishing lures, so they are not precise enough. The hinges are big and sloppy, they don’t have locating dowels to align the 2 halves exactly, and lastly they don’t have relief lines scribed on the inner surfaces to allow for escaping gas.
but, hey; give it a go and let us know how they shoot. Penicillin was discovered by mistake, right?
Do-it molds have a blank mold you can buy, it’s made of aluminum and has a hinge. I don’t know if this will help you in any way, but I thought I would throw it out there for ya.
http://do-itmolds.com/shop/index.php?route=product/category&path=1_11_92
Jerry, you pour more slugs in a week than I’ll likely do in the next ten years. You’ve certainly a significant level of knowledge on the subject.
If you think the guys wasting his time and money attempting to do this, you’re probably correct. Thing is….it’s his time….his money.
It’s been explained to him that it won’t be easy…that the chances for success are minimal to zero…if he makes the decision to go ahead anyway, why should that bother anyone?
It’s no skin off anyone’s ass if he spends the next 5 years trying to dremel a mold that’ll work is it?
My personal thinking, is “Let the man give it a go.”…his eyes are open, he’s evidently willing, and hell….we ALL might learn something in the process.
Or perhaps I’m totally misinterpreting the tone and context of your posts…in which case I do apologize, and should just shut the fuck up and go back to bed. 😆
Al
I’ll be using a sharp spoon for my next mold. Thank goodness I have the length worked out to the gnats ass…
Keep in mind…the aluminum mold will grow when up to casting temp as well. Further complicating things.
Thanks Gippeto. When I’m making and finished making the molds I’ll be casting pellets from polyurethane for checking measurements. It’ll be interesting comparing them to the actual pellets. If the pellets do deform significantly enough for me to measure, they will probably be oblong because of rectangular dimensions of the mold.
Aww hell, more info I forgot to add to my last post.
I ran my estimated numbers through the Miller equation and got a maximum length of .49. Really? A half inch projectile will be stable? Well it didn’t sound right to me and I figured that’s just another case of “well it looked good on paper” but those EunJin pellets measured approximately that and while not very accurate, they do manage to at least make round holes. Again these calculations aren’t actually for pellets so take them with a pinch of salt.
That .22lr is .014 shorter than the EunJin
Since nobody corrected my math I guess I fixed all of the mistakes and will be going with the calculated maximum limits of 35gr in weight so I can reach ~950fps and .49″ length so I don’t need to exceed ~950fps.
I’ll start some rough hand drawings and calculations tonight (weight per volume, etc.) and some cad drawings by Monday. If anybody has some pictures or better yet diagrams of pellets that were particularly accurate in their condor I would like to see as all I’m going off is two pellets that work and a couple that don’t.
Shrinkage allowance for pure lead is 2.6%
Keep in mind…the aluminum mold will grow when up to casting temp as well. Further complicating things.
Where on earth did cold fusion come from? Last I heard it was suspected a hoax that was only sound on paper but if others can reproduce this guy’s work it might re-spark interest(hoaxes can break the scientific process dammit) but for now take it with a heaping spoon of salt. Fusion is more likely to get funding as it’s proven but hasn’t had the bugs worked out yet and certainly not on a large enough scale to be practical.
Edit: Disclaimer, do not attempt to make a fusion reactor in your home kids. It can emit dangerous radiation and if you don’t know what you’re doing on an atomic level you can emit much more unintentional radiation. I make no claims to the accuracy or safety of this information and take no responsibility for damages to property or injury/death.
Look up “farnsworth fusor” sometime and you’ll see a working fusion reactor you can make in the home. Why it does not “work” is that it’s very hard to precisely control the electrons into the center, the electrodes wear out, and a lot of the energy is wasted “breaking” other atoms(like the electrodes) and radiating broad EM… Ok, I see you sleeping back there, fine… and it is slightly off topic. Google it, it’s interesting stuff if you’re a geek.
Well not much work got done on this today but I searched around and found something interesting that might come in handy to you powderburner since you said you were going to work on some ammo in the future. I was dubious about applying calculations designed a long time ago for high velocity rounds but there seems to be newer work I never knew of. Check it out if you haven’t heard about the Miller stability factor. You can find a .pdf here http://www.jbmballistics.com/ballistics/bibliography/articles/miller_stability_1.pdf If you don’t want to read it all or are like me and not good with all the math, there is a calculator on the site here http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi If I were taking this more seriously I would call up the manufacturers or email them to see if I could pry some info how they get their designs.
Necrosis, I set my max at 70 to give me a little leeway. Heavier pellets tend to get more muzzle energy from a PCP and there are unaccounted factors like how friction will be different in my pellet vs the EunJin I benchmarked with. Either way I’ll maybe try out a few designs and intentionally put some outside of the calculated stable boundaries just to demonstrate pellets hitting paper sideways.
Hey there Walt, more specifically the Walt in Hawaii. I might add to it from my own personal experience that bubbles tend to be a problem in smaller molds. I once tried to make a club emblem out of lead from a carved plaster original for a friend back in high school and then electroplate it in copper. I decided to go recycle tire weights since they were freely available on the ground. Big mistake, the alloy they used did not fill small spaces in my mold and had lots of bubbles. I’ve head long ago (I think around the same time) not to cast lead from spent bullets you didn’t make yourself for just this reason, swaged bullets have more leeway with their alloy than cast.
I understand what you’re saying Walt. You bring up all good points and I’m on the same page with what you’re saying. This seems ridiculous and bound for failure (depending on what you consider failure) Even if I had a precision machine shop and an expert machinist looking over my shoulder casting wouldn’t be my first choice because everywhere I hear, cast pellets just do not shoot as accurately as swaged and swaged aren’t very effective either (probably a matter of design since store bought pellets have to come from somewhere and I don’t think a CNC lathe is at the top of that list).
However I’m subleasing and couldn’t run the proper equipment in my apartment even if I had the space and already owned them. I’ll probably not own a home for another 5 years and it’s possible that I’ll never own a home in my lifetime. In other words, I have to use what I have and while I won’t get any tack driving pellets out of it, I’ll get amusement with yet another thing I dove into the deep end on and learned from. Maybe some of the research I do will come in handy to somebody starting out with the right materials. Maybe they’ll say, if this guy did it why the hell can’t I do it better? Maybe they’ll say “that’s what I was going to do but it looks like it’s been done” If anything it may help solidify why certain things will and will not work. Either way thanks for the constructive criticism, constructive being the key word.
Now for the material of the mold yes I was intending to use some 6061 bar stock. I can’t make a cherry from good cutting steel so I’ll fashion something from a lesser steel (I have something in mind already) and hope it stays sharp for at least one cut. They will be disposable in this case. You seem pretty knowledgeable in this so do you mind if I ask your advise (or if you can refer me to someone) when the issues I’m thinking of come up or will you be watching here for long? I guess I could ask one now. I know lead will shrink when it cools, not as bad as wax or thermoplastics but I’m sure there is way to estimate how much it will and oversize the molds a little. I’ll have to get to that later unless someone has an answer already. Aloha
Nope, way too hot!
You mean her???? 😆
Cold fusion comes around every now and then and so far has always been a hoax or case of wishful thinking. I can’t hazard a guess about this time but as always, I hope it’s a breakthrough!
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Yeah, maybe he is. But, that’s one of the perks of being right. Banana, in case you didn’t know, Jerry casts more bullets (pellets) in a month than you’ll cast in your life, probably. He’s not talking just to talk. If he’s got something to say about bullet casting, I’d listen.
walt