Of moulds, masses and materials

[JohnH]

Friend sent me a new Lyman 311284 to make us some boolits with. It's a two cavity. Iron (steel?) Several weeks back I bought an NOE 434429, aluminum 2 cavity. I was running both of them today and noticed something which made me think of an idea had had some time back but had not thought of it in a long while. Preheated the moulds on the wood stove as I was getting the furnace up to temp and after a few casts with each mould was throwing good boolits pretty as you please. I have an aluminum plate (1/4" thick, 12 x 16 or so) under my furnace that I rest the moulds on after each rotation. As I cast, the NOE would begin to drop boolits with slightly rounded edges on the front driving band or show a not quite wrinkle on the nose. At first I thought of the directions, and that one should smoke the mould for the first three uses with a Bic lighter. So I did so, and the boolits began to drop nice again. Meanhile the Lyman was casting like a dream, to perfect boolits every drop. Yet the NOE continued over time to need some attention. It finally hit me that the problem is the big bodied NOE is simply loosing heat, and the Bic lighter is doing little more than raising the temp of the mould back to a proper temp...

I have over time wondered just what effect the mass of the mould block in relation to the mass of the boolits has on the "castability" of a mould. I generally have found that Lyman moulds cast quite well for me. The ones I have are all similar to this 311284 in that the boolits are large when compared to the mass of the mold. In fact, when I first began casting I had a Lyman 429421 which I couldn't keep from frosting. I thought something as wrong with my alloy, or I wasn't keeping the metal fluxed right or... Nada. I currently have two RCBS molds, 257120 and 30150CM, both cast quite well but require a good preheating to get them up to speed. Years past I had an RCBS 32098SWC that as the dickens to work with. That little boolit in that huge iron block just barely kept all than iron at temp. Did fine once you got there, but getting there was bear...


I'm convinced, at least in my own thinking that the six bangers I have (Lee's) cast so easily because of all that boolit metal on that aluminum. They heat up good and it ain't hard to keep it there, most of the time the trouble I have with them is they break my casting rhythm because it takes longer for the sprues to cool well prior to opening.


So, is there a balance point between the mass of the boolits and the mass of the mould which affects castability? What is that point, is there a way to know? Have others observed this, and does the answer lie in the direction of the smaller the boolit the more cavities one should get in the mold? Finally, what methods if any do any of you use to maintain mould temp during a casting session other than relying on the boolit metal alone, i.e. placing a mold on a hot plate...

[tazman]

When I am casting with any of my aluminum molds I only run one mold at a time. This way I can run the mold fast and keep it hot. It doesn't get a chance to cool off too much.
I find switching back and forth between two molds to be a little clumsy for me. Partly because I don't have much room where I cast. Partly because I can't handle the molds fast enough to keep them hot.
I get just as many boolits done in an hour when using a single mold in 4, 5, or 6 cavities as when I try to run 2 molds and have a lot less hassle.
Also when casting with just one mold, I don't set it down on anything and lose heat.

[gwpercle]

Aluminum blocks loose heat faster than iron, they also heat up faster than iron. I am sure there is some optimal block size to material for heat loss - heat gain, but the realities of life are the mould maker has to size them so he can use a standard size of material. I guess you could pay for a custom size block but would it be worth it?
I do like Tazman, cast with one aluminum mould and regulate my speed (I'm a slow person by nature) or cast with two iron mould's , I can fill sit one, set it down and fill the next and by that time the sprue on the first one is ready to cut.
Casting with one iron and one aluminum mould would seem to be a bit frustrating.
Gary

[depoloni]

My thoughts would be in line with what others mentioned above - the aluminum blocks are losing heat faster than the steel ones.

The larger (as a percentage) the volume of the bullet vs. the volume of the mold blocks as a whole, the quicker a given mold should get to proper temp while casting and the quicker it'll get hot while casting - aluminum vs. aluminum, steel vs. steel, etc. I find that I have to hustle to keep some molds at proper temp (i.e. 95gr. .356 for 380). I sometimes have to slow down for an oppositely large bullet like a 300gr. 44-cal bullet in the same size blocks, even during the same ambient conditions, because they get too hot.

When I cast with pair of molds, one being steel and one being aluminum, two things seem to happen:
If it's COLD outside, all things being equal, I eventually have to start dropping TWO castings out of the aluminum mold for every ONE drop from the steel or the aluminum mold (generally) gets too cool and starts rounding edges.
If it's HOT outside, same thing... have to start to go 2-to-1 in favor of the aluminum mold.

When it's cold, I have to stay on the aluminum to keep it warm, while the steel retains more heat.
When it's hot, I have to up-tick the aluminum drops to keep the steel mold from overheating.

Just my 1 cent, my experience. I'm still furiously studying the ridiculous amount of info here to make my opinion worth two. Someday... :)

EDIT: Forgot to add... the mold smoking with the lighter is doing almost *nothing* to re-heat your mold. It's applying carbon soot to the surfaces inside, which acts as a non-stick agent in the cavities thus bringing back those crisp edges. I believe this is a temperature issue.

[Bzcraig]

All the above answers have valid points and like Tazman I only run one mold at a time but not for the same reason. For me, casting is not getting to the destination asap but rather a time to enjoy the ride. Once I get my mold up to temperature, if I want to take a break I will set it on top of my furnace and see how pretty the boolits are coming out by rolling several around and inspect while they are still hot. Casting is really therapy for me, idle hands being the devil's workshop.

[upnorthwis]

I could have started this thread myself with the problems I've had with my new NOE mold. In three casting sessions still haven't made a good boolit. Have pot maxed out at 800, don't throw sprues and reject boolits back in pot, mold preheated by sticking it as far in to Lee pot as possible, pour a sprue as big as possible, cast as fast as possible, and am up to 16:1 mix. Those two .25 cal. 116 gr. cavities are being over powered by a block of aluminum half as big as the battery in my 4-wheeler. Today will try the 1000 watt Lyman pot with the electric hooked up direct. Maybe I can get good boolits at a 1000 degrees. If this doesn't work, I have a mill and material will be removed. Looks like I can take a quarter of an inch off the bottom alone.

[JohnH]

I could have started this thread myself with the problems I've had with my new NOE mold. In three casting sessions still haven't made a good boolit. Have pot maxed out at 800, don't throw sprues and reject boolits back in pot, mold preheated by sticking it as far in to Lee pot as possible, pour a sprue as big as possible, cast as fast as possible, and am up to 16:1 mix. Those two .25 cal. 116 gr. cavities are being over powered by a block of aluminum half as big as the battery in my 4-wheeler. Today will try the 1000 watt Lyman pot with the electric hooked up direct. Maybe I can get good boolits at a 1000 degrees. If this doesn't work, I have a mill and material will be removed. Looks like I can take a quarter of an inch off the bottom alone.

Was my NOE got me to thinking on this again. I just wonder if a hot plate set on low with a piece 14 or 16 gage sheet metal on the eye (1/8-3/16???) to keep the heat in the mold as I'm working another is not the answer (I'm gonna find out ;) ) I don't have any trouble running Lee 2 cavities molds while running iron molds from Lyman, RCBS or SAECO, but the Lyman blocks are tiny compared to the NOE. I think the NOE is larger than my RCBS molds, but I've not compared them as yet... My first run with the NOE I ran it alone and didn't have any problems, that could be an answer too
, but I usually like to make two different boolits in a run.

[gwpercle]

I also have enjoyed casting boolits since day one. Therapeutic.... yes that describes it exactly.
Funny thing is I don't try and complicate things, no thermometer, fancy pots or anything other than Lyman and Lee moulds , (2 cavity), Lee electric pot and Lyman ladle, no bottom pour. And other than over lubing pins and contaminating the cavity with lube occasionally , I don't have any problems casting good boolits once the metal, and clean mould get up to temperature.
Don't use a hot plate or have a decent custom mould. Maybe ignorance is bliss!
Gary

[44man]

I found that with a big, brass mold, could barely keep up. used a propane torch a lot.
But I do cast with two molds a lot and have done 3 at a time. Mix of my aluminum and Lyman steel.
I set the mold on a hunk of hardwood, don't use metal.
It seems to be true that a large mold will lose heat faster. The brass mold got to weigh 100# after a while! Give wrist problems faster then shooting!

[ballistim]

I found that with a big, brass mold, could barely keep up. used a propane torch a lot.
But I do cast with two molds a lot and have done 3 at a time. Mix of my aluminum and Lyman steel.
I set the mold on a hunk of hardwood, don't use metal.
It seems to be true that a large mold will lose heat faster. The brass mold got to weigh 100# after a while! Give wrist problems faster then shooting!

Bought a shelf kit for my 20lb. Lee pot from a member here who sells them, and it's adjustable for the perfect distance for the bottom pour with a back stop so the mold lines up easily allowing me to use 4 cavity brass molds without fatigue. Anyone here can look for the thread with the contact info if interested, highly recommend it!

[Screwbolts]

I can only ask why have you only got double cavity NOE molds? I use a bottom pour 20 lbs lee pot on 220V.

The more cavities the easier they are to keep hot, more alloy running into the molds. My 5 cav NOE molds love to cast at 625 to 650. (Currently have 8 NOE molds) That being indicated on my NOE thermometer.

For a small pile of pennies more, (Less than a tank full of gas even at todays gas price) you could be running 5 cavity molds that have 2.5 times the amount of alloy running threw them with each pour.

I recently sold my Arsenal 2 cav, 311331 to, Ken In Iowa. If he finds this thread, Ken, please comment on its casting ability. :-) I found it liked to run at the same temps as my 5 cav. NOEs. It was a pleasure to run, but slow by my standards. Yes the 311331 is a long boolit and heats the small blocks well but I run them as fast as the sprue sets, off they come by sliding the plate, no tapping one of my molds once they are hot. I quote from Ken in Iowa, "the boolitz almost jump from the mold." It runs that good when hot.

Jared has already sent me a 5 Cav of the same mold, it should be here Tue. 1-20-15.

Run them fast and that keeps them hot, that is what they like, IMHO

Ken

[ballistim]

I first learned to cast from an older guy who only used single cavity molds because of differences in each of multi cavity molds. NOE and MiHec molds are precise on their dimensions from what I've experienced. Lee has some great designs and are value priced but I have to be honest that I've had both mis-alignment & undersized cavities, loose pins, etc.
Lee molds have often had quality control issues in my experience.

[Handloader109]

I agree with your assessment Johnh, I've a NOE casting little 95 grain hps and I have a hard time getting it going . part of it is the pins sucking heat out, but it is a big mass vs the little 2 cavities. My little lees probably have half the mass.

[JohnH]

I can only ask why have you only got double cavity NOE molds? I use a bottom pour 20 lbs lee pot on 220V.

The more cavities the easier they are to keep hot, more alloy running into the molds. My 5 cav NOE molds love to cast at 625 to 650. (Currently have 8 NOE molds) That being indicated on my NOE thermometer.

For a small pile of pennies more, (Less than a tank full of gas even at todays gas price) you could be running 5 cavity molds that have 2.5 times the amount of alloy running threw them with each pour.

I recently sold my Arsenal 2 cav, 311331 to, Ken In Iowa. If he finds this thread, Ken, please comment on its casting ability. :-) I found it liked to run at the same temps as my 5 cav. NOEs. It was a pleasure to run, but slow by my standards. Yes the 311331 is a long boolit and heats the small blocks well but I run them as fast as the sprue sets, off they come by sliding the plate, no tapping one of my molds once they are hot. I quote from Ken in Iowa, "the boolitz almost jump from the mold." It runs that good when hot.

Jared has already sent me a 5 Cav of the same mold, it should be here Tue. 1-20-15.

Run them fast and that keeps them hot, that is what they like, IMHO

KenReally? Maybe those small pennies, that price of a tank of gas would have been the difference between having this mold to work with or not going to work the following week. It's damned hard not to take this comment personally, but some of us actually are doing the best we can and don't have a lot to go around. It could also be the fact that the money I used to buy the NOE had been part of a gift and the remainder was used to buy a gift for someone else. May I suggest a re-reading of "A Christmas Carol", Charles Dickens.

[Screwbolts]

We are all doing the best we can. Nothing posted was meant to be taken personal by anyone. I meant no discomfort to anyone. It is my opinion that the $20.00 difference between a 2 cavity and a 5 is not much for the return you get on your money. The tools to run the mold are all the same, Nose punch is the same, I believe shipping cost is the same. Because of higher production speed of casting,and possibly ease of casting, cost of electricity to keep pot hot is less because of less time casting. That can be a savings. None of us have money to waste, and all are doing the best we can with what we have.

Ken

[JohnH]

We are all doing the best we can. Nothing posted was meant to be taken personal by anyone. I meant no discomfort to anyone. It is my opinion that the $20.00 difference between a 2 cavity and a 5 is not much for the return you get on your money. The tools to run the mold are all the same, Nose punch is the same, I believe shipping cost is the same. Because of higher production speed of casting,and possibly ease of casting, cost of electricity to keep pot hot is less because of less time casting. That can be a savings. None of us have money to waste, and all are doing the best we can with what we have.

Ken

Ken, I've no doubt I over reacted, let my emotions overwhelm me. The words hit me wrong, a perfect example of how communication on internet forums can suck. No doubt what I heard was not what you meant. I as going to delete the thread, but couldn't figure out how. I thank all who have responded to this post, gave me some ideas, from running the NOE by itself to trying out a hot plate to keep it's temp up as I cast. Obviously I'm not alone in observing this heat loss phenomenon, and that is as much as what I was seeking as anything, making sure I wasn't nuts. Thanks all. JohnH

[country gent]

In reality more mass should hold heat better than smaller less massive blocks. But it also takes more to heat them fully up to temperature. I dont cast with aluminum any more but 2 cavitie lees heated up fast and stayed hot. My lymans do very well also. 2 steel rcbs had to be overfilled and cast alone and at a very fast pace along with a longer pre heat to get good bullets one was 22 cal 55 grn and the other was 243 100 grn I believe. Niether put enough metal into the mold to stay hot. My only brass mould is a old west 40 cal 400 grn and casts great warms fast and stays hot. These are large blocks and brass. I heat and cast a a casual pace. It is single cavity so around 80-100 / hour or so. I normally start with this and switch to a lyman or other mould towards end of session. Steel moulds sitting on concrete floor cool out in about 20 mins, This brass mould takes close to an hour or so to cool out to touch. Once heated you can sit it down flux and move bullets around and just start casting again. As to materials heat holding abiities brass steel then aluminum. Brass and aluminun heat much more even than steel so it may take a little longer for blocks to come up to temp with these materials also.

[edctexas]

I have lyman, lee and quite a few NOE molds. The lee molds are easy to get up to temp and seem to run cooler that the lyman steel mold. The NOE mold like to be hot. I bought the probe and measure their temp. My hot plate runs on a PID so I know roughly what the hot plate temp runs for a given mold temp. The NOE molds for 45ACP , 44Mag, and big 357 need about 425F. The 90gr, 123 gr, and 30 cal mold like 475F. These mold temps give about a 5 sec sprue hardening when poured at 700-710 lead temp. I like the aluminum molds. I just wish the lee molds threw the spec'd diameter and did not need any "fiddling" to keep them running.

Ed C