Whats the cause of this?

[jdgabbard]

On the base of the boolits Occasionally I am getting a Clean cut on the sprue, and the bases are filled out properly. However where the sprue was cut on the base there is a little crater of missing material. Almost like the sprue plate tore the sprue out instead of cutting it off.

Any suggestions?

[Snapping Twig]

Typically that happens for me when the mould is too hot and I hit the sprue plate too early, that and when the mould is too cold. So I'd venture to say it's temperature related.

[ktw]

You are opening the sprue plate too soon. Let the mold sit a few seconds longer until the craters disappear.

-ktw

[jdgabbard]

So you think I am casting too fast? Ok, I will give it a try and see how that works.

[mstarling]

Cadence is everything!

Yup ... you're running just a bit too fast. You might also see smearing of alloy across the back of the sprue plate if it's really too fast.

[mooman76]

You can either turn the heat down or like ktw said wait an extra second or two. Since some are coming out good and some aren't you must be pretty close to where you need to be.

[Bigjohn]

It is a sign that the metal is still a bit hot and not set (cooled) off properly.

The other posters here have 'nailed' it.

Another solution is to have a heat sink handy and rest the mold on that to draw some of the heat from it.

I know of a local caster who has a 1/4" plate of aluminium with a number of holes drilled through it and a computer fan mounted under it; blowing air through the holes.

And last but not least; cadence; the rythym at which you cast. Maybe just slow it down a little.

Best of luck,
John.

[DLCTEX]

With one and two cavity molds I blow on the sprue to hasten it's cooling. I found the opposite effect, a raised bump on the base where the sprue is, is eliminated by pressing down while cutting. DALE

[runfiverun]

i will occasionally touch the sprue cutter to a damp rag to help it some, if the boolits are formed well, and i am at a happy speed ,it will just cool things down some without undue stress to the mold.

[Ben]

Damp cloth or Damp sponge will solidify the sprue without you having to slow down too much.

The next thing to watch out for is the entire mold frosting the bullets. Then you know that the mold, alloy or BOTH are way too hot.

Ben

[cajun shooter]

When casting, I at times after cutting the sprue and dumping the bullets; open the mold block and let the fan do it's thing for about 20 seconds. Then resume casting for awhile before repeating the process. Youn will have much better casting sessions by slowing down.

[jdgabbard]

I will give it a try. However, one thing I noticed is the speed I am at now is what I had to do to get rid of wrinkled bullets. Still a few pop out wrinkled. This is mostly because I am casting outside. And believe it or not it has been fairly cold here in northern oklahoma.

I too have noticed a raised bump on the base of the boolits from time to time. But I haven't seen ANY smearing as of yet. Just a question. These craters are mostly just cosmetic in appearance right? I mean, they will shoot fine, correct?

Funny thing is that I need to add some tin to the alloy. Been casting straight WW. And a soft bump on the boolits leaves a dent. Gonna have to load these for low velocity .38 spl. When I start smelting the rest of my WWs I am gonna add some 50/50 solder to each batch to bring the tin content up 1%. Should be about 70gn a pound. Right?

[JIMinPHX]

As many have said, waiting longer for the sprew to cool is your first line of defense against this problem. Sharpening up the sprew plate can also help.

[Dale53]

After the mould is up to heat and casting well (I pre-heat the moulds on a hot plate and they are up to speed in a couple of casts) I use my gloved hand to "twist" the sprue plate instead of whacking it with a stick. I find that I have MUCH nicer sprue cuts when doing this.

I use this up to and including four cavity moulds without a problem. I am NOT man mountain dean but a certified "old fart" with no more than normal strength. It is EASY and it is also easier on my moulds.

Just a suggestion...

Dale53

[Le Loup Solitaire]

Hi, As other forum members have pointed out...metal may be too hot and you are not letting the sprue puddle solidify completely. It'll also lead to lead smears on the top of the blocks and also on the underside of the sprue cutter. Both are a pain and a problem that you don't want or need. Cast slower, giving the puddle longer time to set up before cutting the sprue. Also using a second mold in tandem gives you the time for that to happen. I have succesfully used one of those mini desk fans sold in Ace/Walmart/Lowes or Home Depot for around 10-12 dollars. Set it up so that it plays across the mold top when you put it down prior to cutting the sprue. Works slick when you get the rythm. LLs

[Will]

WW metal contains about 1/2% tin. at 7000 gr to the pound that would be 35gr of tin and require another 35gr to bring a pound of WW to 1%. Your 70gr of 50/50 would be the correct amount to add to bring the pound of WW to 1%.

This is the mix I use for most all my casting.

Will

[jonk]

So far as how they will shoot; I've not found the craters to make much difference for hunting accuracy or just punching paper. For target work, especially over 100 yards, yes they probably do. Not the crater per se but the inconsistency from bullet to bullet.

[madsenshooter]

I think the alloy has a bit to do with it too. Seems the harder I try to cast the bullet, the more craters I get. They're not consistent, and not in the center of the base either, so they have to throw the bullet out of balance. Seems the more antimony I try to use, the more the alloy crystallizes and the bigger the divets get. When you think about what's happening when we strike that cutter you'll understand. About the same time the hole in the sprue plate starts to cut, a wedge is hitting on the side of the sprue pulling what is yet uncut upwards. You've started a cut, or a crack, and the wedge driving the sprue upward does the rest. This inconsistency in the base is why a lot of target shooters use nose pour molds. Some say a bit of inconsistency there makes less of a difference than on the base. I've found using a plastic mallet and really giving the sprue plate a whack helps some, double whacks make more divets, quick and clean cuts are necessary. We've moved away from the thinner sprue plates, most like them nice and thick, but that's just a bigger wedge that amplifies the problem. Forgot the raised bump thing, tightening the sprue plate screw will help, on those, you're hitting at an angle and driving the loose sprue plate upward a touch. Lining up a good level hit on the sprue plate will slow you down and give the bullet base a little more time to solidify too. Practice, practice, practice, then get frustrated! :twisted:.

[jdgabbard]

Will, about how hard is that alloy? BHN?