Help me with my cast bullets, please.

[Brother_Love]

I finally got some casting done today since it was a little cooler (94). The 35's are from a new NOE mold that I prepared just as the instructions directed me. You can see from the photos that some of the bullets look almost perfect and others look really bad. I had to cast a little hotter than I like to get the mold to fill out right.

I am not going to get my feelings hurt, I really want to know what I am doing wrong. My pot was just cleaned out 2 weeks ago and I am using Lyman #2.

The .30 caliber was cast from a Lyman mold for a 30-06. I use Aluminum molds but I prefer a steel mold and I seem to cast better with them.

Thank you, Malcolm

 

[RicinYakima]

Inclusions in the first picture are simple dirt. Your alloy is not clean, so use some wax and scrape everything better and remove it. What ever that white thing is the bullets are on is plastic. Get rid of it!!!! Only use pure cotton or you will have that stuff back in your pot. Go to the fabric store and find some 100% cotton material to drop your bullet on. It appears your alloy is plenty hot, but the mould is cold; cast faster. HTH, Ric

 

[Brad]

Mould temp. Not melt temp but mould temp. Preheat the mould a bit longer and see if you can speed up the casting tempo a little. Pour, cut sprue, dump. Repeat. Don't stop and look at bullets. Refill the mould as soon as possible after dumping the bullets.
Notice the frosted nes have better fill than the shiny ones? Mould temp causes the difference, frosted is a hotter mould.
Find a rhythm with each mould that keeps the mould temp in a zone that gives lightly frosted bullets.

You also look to have some impurities in the melt. I would flux with some sawdust and stir the dickens out of the melt. Scrape the sides and bottom of the pot with a metal spoon.

The frosted 35 plain bases look pretty good.

 

[Cherokee]

Couple of things I noticed: Looks like you could have used more heat in the molds, looks like some trash in the metal, and in the last pic, looks like the mold might not be closing completely.

edit: others posted while I was typing

 

[gman]

Agree with above statements. Pre heat your mold on a hot plate while your alloy is melting and getting to correct temperature.

 

[Brother_Love]

Thanks, I have since I wrote the first post fluxed the melt again with sawdust. The 30 caliber was cast after that. I will get a hot plate next week to preheat.
Thanks again.

 

[Rick]

Most such problems are due to a cool mold. Aluminum sheds it's heat far faster than an iron mold and casting rhythm needs to be adjusted accordingly.

The inclusions in the bullets are from dirt in the alloy from improper fluxing or not using a true flux. Fluxing isn't a sprinkle on top & quick stir. It takes time & patience to be sure the alloy is clean. When bottom pouring do not add rejects, sprues or ingots while casting. The reason is the cooler alloy will sink before melting and any impurities at or near the top of the pot will be dragged down with them.
.

 

[KHornet]

I am fully with Brad on the heat with alum molds. The more cavs, the more it is true.
Forget looking at them until you are done casting, establish a time sequence and maintain
it as long as you can. Use Bullplate, or similar, and cut sprew as soon as it starts to change
color. A little frosting is a good sign that you are hot enough. Bright and shiny to me with an
alum multi cav mold means to cool. Just my opinion!
Good luck!
Paul

 

[Ian]

The reason is the cooler alloy will sink before melting and any impurities at or near the top of the pot will be dragged down with them.
.

Rick makes an excellent observation here as usual.

Oxides are impurities. I see oxide inclusions in the first picture. Bullets and sprues are covered in oxidized metal and will sink to the bottom where the oxide skin gets stuck until it finds the spout due to flow currents. Even if the surface of the pot is clean of all dirt and ash, the oxides will still get carried to the bottom and cause inclusion issues, most of which are hidden inside the bullets and you won't see. If you DO see them, the problem may be worse than you imagine.

Mould heat (or lack thereof) and a new mould that hasn't accumulated a nice layer of aluminum oxides on it yet are the other two issues I see from the pictures. Keep using that mould so it breaks in, preheat it and keep it hot by increasing your casting pace, and don't run your alloy any hotter than 725 is my advice.

 

[fiver]

even with the heat cycles the NOE's need some casting cycles on them too.
I run my 8mm mold from them a few times and was hating the mold, but since I was just using them as cores for other things [swaging] I was fine with it.
then suddenly I broke the mold in.
I picked it up and started pouring a pile of boolits and they were just falling out of the mold well filled out and consistent, it's become one of my easiest to operate molds since then.

 

[JonB]

I finally got some casting done today since it was a little cooler (94).

I hesitate to give advice on this forum, due to all the folks here with decades more experience then me, I usually only participate here with questions and trying to learn. But no one has asked the obvious. Are you using a Fan to keep yourself cool while casting in this hot weather? and is it positioned where it could be cooling your mold ?

You may already know this, but I find long rifle bullets troublesome to cast. Keeping the mold temperature hot enough and uniformly hot, to get good fillout can be challenging, especially with fans moving the air in the casting area.

Other molds, with large cavities have the opposite problem, where I use a fan to blow in the casting area, specifically to cool the mold, to speed up production. This tells me, that air movement can significantly cool a mold. Ian told me long ago about Mold temperature, but I tend to learn best by trial and error, so until I tried a few things myself, I never really grasped what the best temperature a mold needed.

 

[Brother_Love]

Lots of great help here! Thank you. This afternoon I plan to rip up some scrap lumber and make a pile of sawdust. I also may wait until November to try casting again.

 

[KHornet]

Long ago, I quit fluxing with any thing other than a soft pine wood dowel.
I stur with it, scrape the sides of the pot, it smokes the same as sawdust, but
not as much, and I believe I put an adequate amount of carbon in the mix
as needed. Don't recall where I picked up the idea, but it was probably on
some forum a long time back. The paint stur sticks that most paint stores
give away also work great, and have the advantage of having a flat bottom
that sort of scrapes the bottom of the pot. It is one of those things that works
for me, so I don't fix it.
Paul

 

[Rick]

Considering a melt temp of 700 degrees which is well past the heat needed to char the wood how do you keep the pieces from flaking off while rubbing it on the sides & bottom and of course being trapped in the alloy? The carbon needed from fluxing isn't needed "in" the alloy but rather at the surface to reduce Sn & Sb back to the elemental metal of the alloy.

You are correct of course that if your happy with your results there is little need for "fixing it". There are others however that could appreciate a different perspective.
.

 

[waco]

even with the heat cycles the NOE's need some casting cycles on them too.

I have noticed this myself. I was kinda bummed about a four banger I bought from Al but after about the third time using it, it was like someone flicked a switch. Running through the heat cycles is good, but nothing beats just using the mold a few times.

 

[300BLK]

All moulds will drop more perfect bullets after they have some oxidation in the cavities. Aluminum generally needs more heat than ferrous alloy blocks, so adjust the temperature accordingly. Judging by the looks of some of the bullets, I'll bet you're bottom pouring. Surface inclusions (dirt) is less prevalent when casting with a ladle. My preference is to an older Lyman ladle with the hole in the spout drilled out larger. I WILL pressure cast IF the vent lines in the mould will allow it.

 

[Brad]

My first NOE mould was when he was just starting out. I hated the mould the first few sessions. Bad bullets with ever pour. I cleaned it again and no better. About the fourth session it got right and I was very pleased.

Rick, I know the likely answer but do you have the ability to shoot a video or series of photos showing how you flux?

 

[Ian]

If you don't scrape the bottom with your stick, you won't get junk trapped in the alloy. The finings will make their way to the top eventually.

Jon, Bret was the first person I noted on these boards mentioning fluxing with a paint stir stick. Keep in mind he ladle pours, which makes a big difference and is something he didn't often mention along with the advice to scrape sides, bottom, etc. and stir with the flaming stick.

 

[fiver]

the best pot scraper I ever made was a hack saw blade I heated and bent over the last 1-1/2 mK-1 eyeballed inch over into a 90*.
then cut a little piece of broom stick with that same blade [sawed a groove down into it] and JB welded it into place.

 

[KHornet]

Like the bent over hack saw blade for bottom scraping.
Think I will try that Fiver! Thanks!
Paul