Why is the sprue cut area a little cratered?

[kryogen]

I notice that some of my bullets have a little crater at the sprue cut area.

For some reason (and I have not been able to exactly understand why), it seems that when I pour my lead above 680, the sprue "waste" breaks when I drop it on the pan.
When I pour lead at 680, it just dumps there, solid. and the bullet bases are fine.
And when the sprue scrap "breaks" easily, there seems to be a little crater at the sprue cut area.

Now, I'm not talking about a huge hole, but there is a visible depression like when the sprue was cut, some lead chipped away with it.

Any clue what is causing this and how to prevent it?

Should I open the sprue plate when the lead is still quite hot (but has solidified), or wait longer, like 20 seconds, to make sure it's really solid?

I have a PID incoming in the mail, maybe this will help me keep the alloy just above the temperature where it will not flow out of the pot. It seems that below 650, the bottom pour jams. At 680 or so, it's fine and it seems to cast the best, without overheating the mold, and with less sprue craters.

Anyone has anything to say?
Oh, and even at 680, the bullets are frosted. Below that, the spout jams... why?

Mix was straight WW, cast between 680 and 750. All gave good fillout with a hot enough mold.

[nhrifle]

What's happening is exactly what you observed. The mould and/or melt are too hot, most likely the mould. Cast a little bit slower and turn down the pot temp until you get the results you want. The sprue should take only a second or two to cool fully before cutting and dropping the boolits. If the sprue puddle seems sluggish to freeze and both the boolits and the cut off sprue are frosted or look like they have been zinc galvanized, you are running things on the hot side. Slow down and cool off a bit.

That said, there is nothing wrong with shooting boolits like that. I do all the time.

[emorris]

Try letting the sprue set a little longer first.

[D Crockett]

the reason you have a crater is you need to get some bullshop spew plate lube but I just looked on the sponsor list and did not see his name on the list this stuff will stop that crater problem you have. you might be able to get someone here to sale you some D Crockett

[Old Caster]

If the sprue breaks when it falls from the mold, it is too hot. If you keep this up, it will smear the bottom of the sprue plate also. If you have to cast at an elevated temperature because of spout freeze, you will also have to slow down so the sprue has the chance to cool and solidify.

[wallenba]

You are cutting the sprue off while it is a little too soft, and it can tear out. Allow it to cool a little bit more first. Poke it with something to see if it is still elastic. Also, this can lead to lead build-up under the sprue plate, leaving an arc of alloy on top of the mold and the bottom of the plate. Enough so that it can lift the sprue plate a bit, raising a sprue bump. Not good if you are using gas checks.

[Dan Cash]

An added advantage of waiting longer to cut the sprue is you let the bullet harden, particularly longer ones like 180-200 gr .30s. If they are dropped too soon, they will bend. I give my pour about 10 seconds to cut and open. It is a temmperature issue; lube will not help and may infiltrate the nould cavity bringing the session to an end while you clean the mould.

[Gtek]

Tear-hot, hammer cut- cold. Cadence, if pot is the same count in your head. Pour, 1,2,3, puddle change,5, 6,7, 8, 9, dump, whatever works. When you figure out the magic, write it down in your Boolit notebook. Day temp, pot temp, alloy, count, etc. Thank God I do not need to count big numbers, I can only get to twenty one and it takes me a minute or two. Gtek

[dikman]

I had my RCBS set to around 750 (no idea of the actual temp.) and all was working fine. I decided to drop the setting back to just over 650 and started getting freezing issues in the pour spout. Now I know where not to set it, hot is good.
As for the "cratering", I would say that the lead is still in the plastic stage when the sprue is knocked off and is contracting while still cooling off. I have poured some test samples (2" diam. x 1/2" discs), and when they are cooling they contract to the middle and form a dimple. Being an open mold there is nothing to fill the dimple as it forms, so you may get a similar result if you remove the sprue too soon.

[pipehand]

+1 on the sprue plate lube. I also like to cast very hot for good fillout, and keep a small ducted fan on my casting bench to cool off the sprue when things heat up. Fan blows straight down on the mold, and since it cools the molten metal quicker, there isn't time for it to "crystallize", and I get a nice smooth sprue cut. I got the idea from how some of the automatic machines work.

[MBTcustom]

The problem with running your mold too cool is that you will get cutting pressure on the sprue plate. Cutting pressure means caming pressure on the pivot joint, which means your mold will bite the big one much sooner (ask me how I know).
You want to preheat your mold so that even on the first pour, you can cut that sprue with a gloved hand. You want to be using bullplate because when you are running at a consistent temperature and cadence, you are going to get a lead smear every now and then. Consistency is the ticket. You are trying to drop consistent boolits, even if you are experiencing sprue hole plucking. If it's always the same then you've got no worries.
I might also point out that the center of the boolit base has got to be the safest place for a defect to exist, because that little area will be operating in a vacuum, and will probably be covered by a GC anyway.

Part of the problem you are having (IMHO) is that you are casting with straight WW alloy. That alloy is antimony rich and that stuff is like oatmeal in the slushy/galvanized stage. If these boolits are going in a HP rifle that will be shot over 2200fps, then just add a little tin (less than 2%) and I think things will even out for you. If these boolits are being made for a rifle that will be run less than 2000fps, then mix 50/50 with pure lead and then add 2% tin if you've got janky fill out problems.
To be honest though, I'm getting pretty good results from just a 50/50 mix with no tin added. the sprue holes look like a lead sponge in that dot that you say is missing. It's like it plucked, but it didn't rip out the whole enchilada.

The easiest way to get a perfectly shiny clipped sprue is to just run your mold and melt too cool. I fear you would have wrinkly boolits, inconsistent weights, and you would be doing irreparable damage to a mold that should have lasted you 30 years. I know it looks janky, but it's adding years to your mold, and if it doesn't show on the scale or the paper, why worry about it?

[kryogen]

The easiest way to get a perfectly shiny clipped sprue is to just run your mold and melt too cool. I fear you would have wrinkly boolits, inconsistent weights, and you would be doing irreparable damage to a mold that should have lasted you 30 years. I know it looks janky, but it's adding years to your mold, and if it doesn't show on the scale or the paper, why worry about it?

Seems about right, the only time I get nice sprue cuts is when I start, with a mix and mold that are both too cold, and sprue cutting requires force.

Those were 45acp bullets.

If it does not matter, then I don't care, thanks a lot.

[MBTcustom]

If I could venture one more piece of advice?

Buy some range lead and just try it with a good grease lube. Drop them .452 in water, and load them over bullseye. Range lead is awesome in a 45ACP, and that lets you save your precious COWW for something that really needs them.
Give-er a try.

[detox]

When bases start turning frosted Cooling sprue with wet sponge helps cool sprue plate down for faster and cleaner cut...along with a sharp and very flat against surface sprue plate.

[bhn22]

Try letting the sprue set a little longer first.

And there it is. The hotter the melt, the longer it needs to cool before breaking the sprue, or you risk tearing divots out of the bullet base. You can also touch the solidified sprue with a damp cloth briefly before breaking it.

[Shiloh]

As the metal shrinks when cooling, it draws from the sprue. What you have is a thick heavy area, the boolit, constricted by the sprue hole, and another thick heavy area, the sprue button. The thin area cools first, and is being pulled at by molten metal on both sides of it. Try slowing down a bit or a bit cooler if you can still get good boolits running cooler.

When I cast jewelry, going from a thicker area to a thin are, back to thick area, causes problems. Both thick area's need a dedicated sprue gate to have a pool of metal to draw from. Without it you have the same porosity that you witness on your boolit bases. In boolits it is okay. In a piece of custom 14K or 18K gold jewelry, it is totally unacceptable..

Shiloh

[cbrick]

I might also point out that the center of the boolit base has got to be the safest place for a defect to exist, because that little area will be operating in a vacuum, and will probably be covered by a GC anyway.

Silly Mod, that's not something to tell a newbie trying to learn to cast well.

The correct answer is: A boolit defect is a boolit defect even if you cover it up with a gas check or lube or stick it inside the case and can longer see it, it is still there and still a defect. True that some defects could be more serious than others especially depending on what your shooting but a defect is a defect. Covering up a defect changes nothing.

The problem is a temperature/cadence one and practice and paying attention will get you the results your looking for.

Rick

[jmort]

"Mix was straight WW"

I may love tin too much, but many need to put out a little love for tin. It don't take much. Add some freaking tin.

[cbrick]

"Mix was straight WW" I may love tin too much, but many need to put out a little love for tin. It don't take much. Add some freaking tin.

Can't argue with that. I cast almost exclusively with clip-on weights, I blended 800 pounds together for a uniform batch of alloy and I automatically add 2% tin. When adding the ingots to the casting pot I weigh them and add 2% Sn by weight. I simply don't have many of the issues that many people here report such as cast diameter, fill-out etc.

Rick

[jmort]

"I simply don't have many of the issues that many people here report such as cast diameter, fill-out etc."

You have been at this a while and are at the top of the knowledge food chain. I get crazy and use even more than 2% tin at times. Even 1 to 20 which I really like.

[Doc Highwall]

Nobody mentioned to ask if the sprue cutter is sharp, a dull one will tear more while a nice sharp one will cut cleaner.

[plainsman456]

I often cool the sprue plate by touching it to a piece of steel bench or the anvil.

It works.

[MBTcustom]

Silly Mod, that's not something to tell a newbie trying to learn to cast well.

The correct answer is: A boolit defect is a boolit defect even if you cover it up with a gas check or lube or stick it inside the case and can longer see it, it is still there and still a defect. True that some defects could be more serious than others especially depending on what your shooting but a defect is a defect. Covering up a defect changes nothing.

The problem is a temperature/cadence one and practice and paying attention will get you the results your looking for.

Rick

Tricks are for kids.
I agree with you to a certain extent, but then again, I don't care how good you are. If whatever you have in that dot on the base of the base of the boolit was relocated to the driving bands, it would make that boolit a cull, therefore it is a defect, and one that cannot be gotten away from.
The point I was trying to make is that unlike a situation where that blemish was located on the driving bands, if instead it is located in the center of the nose, or the center of the base, that is the safest place for a blemish to exist.
Am I wrong?
I have never seen fellers posting pictures of the bases of their boolits and bragging about how cleanly they sliced off the sprue. Also, I feel that a caster would be rather trapped because it must be cut in a certain time frame in order to maintain proper mold temperature.
I'm going to go take some pictures of the bottoms of my boolits, and I would appreciate critique.

[MBTcustom]

This is a 405gr Lyman mold in 458 caliber
91971
This is a 405gr Accurate mold in 458 caliber
91972
This is the Lyman 358430 mold. 200gr in weight
91973
This is a vintage Lyman 429421 mold
91974
This is the 30 SIL mold.
91975

[nhrifle]

Tim those are terrible. Just awful. :kidding:

I have a bunch either loaded or ready to load that look quite similar and they have yet to pose a problem.

[a.squibload]

...
I'm going to go take some pictures of the bottoms of my boolits, and I would appreciate critique.

Heehee! Boolit porn! :)

Helps to leave plenty of sprue on the plate for the boolit to draw from
as it cools. I tend to wait 10 seconds or more before cutting, also seems
to help boolits drop out of molds.
Some tin (solder, pewter...) will usually help.
Just 'cause your pot has a spout doesn't mean you can't ladle pour,
try it some time. 'Course you have to leave the ladle in the pot
when not in use so it keeps up to temp.

You'll find a rythm that keeps the mold hot enough and cuts
the sprues clean.

PS there are threads here about spout freeze.

[MBTcustom]

This is the only one that really sucks rocks IMHO. I used the same casting rhythm for all of those boolits. These ones were cast with a mold that has a very dull sprue plate:
91976

[leadman]

goodsteel, it appears the sprue plate holes are not centered over the cavities. Could this be a Lyman mold? (went and looked at the pictures again and it is a Lyman) I have had several sprue plates that the holes were positioned similar. I replaced the plates.
Other than that I would have not issue shooting those boolits. I did a test with 2 scoped handguns from a concrete bench with a solid rest, shooting at 100 yards and could not tell any difference between boolits with a slight crater to boolits with perfect sprues. The worst groups were around 3 or 4", with the best around 1.5". Been a few years since I did the test.
Seems like the larger diameter boolits pull the sprue more than the small diameter molds. Probably something to do with cooling.
The alloy does affect this as I made some 30 to 1 lead to tin and it was a real joy to cast with. Seems any alloy with antimony in it can give problems that do not occur with a lead/tin alloy.
With the amount of boolits I cast I would have to take out a loan to buy the tin!

[Doc Highwall]

When I first get a mould the first thing I do is completely deburr it especially making sure the bottom of the sprue plate has a radius where it slides on and off the top of the mould. Then I make sure the hole in the sprue plate is sharp with no burrs, the mould halves are left for last with a small edge break on the top edge to help allow air to escape.
I cut the sprue by hand while wearing a leather glove and I use a squeezing down twisting motion when cutting the sprue. This is why cadence is very important as to when you cut the sprue and having the mould preheated before you start casting bullets.

[cbrick]

91983

[Gtek]

Doc, I like your style. I do the same new or used before the first drop. I have even taken aluminum dowel and turned to fit mold ID with .125" hit in end to check sprue hole centering. If it drops ugly, it must be me. If I missed or pulled, it must be me. Gtek

[MBTcustom]

goodsteel, it appears the sprue plate holes are not centered over the cavities. Could this be a Lyman mold? (went and looked at the pictures again and it is a Lyman) I have had several sprue plates that the holes were positioned similar. I replaced the plates.
Other than that I would have not issue shooting those boolits. I did a test with 2 scoped handguns from a concrete bench with a solid rest, shooting at 100 yards and could not tell any difference between boolits with a slight crater to boolits with perfect sprues. The worst groups were around 3 or 4", with the best around 1.5". Been a few years since I did the test.
Seems like the larger diameter boolits pull the sprue more than the small diameter molds. Probably something to do with cooling.
The alloy does affect this as I made some 30 to 1 lead to tin and it was a real joy to cast with. Seems any alloy with antimony in it can give problems that do not occur with a lead/tin alloy.
With the amount of boolits I cast I would have to take out a loan to buy the tin!

You're correct. They are not centered, the moldblocks don't line up perfectly, and it rips chunks out of the base of the boolits.......and I have cleaned so many clocks with that 200gr boolit in a 38 special, it makes the second hand spin like the button on the outhouse door!
All I can figure is that as long as it doesn't tear out the side of the trailing edge, it's safe in its little vacuum.

Doc, I also open the mold exactly as you describe, and I prep my rifle molds as you have described. Never cared much on pistol boolits
:oops:

cbrick, I need to come visit you again, and this time, less talky, more casty eh? LOL!

[Full Mold Jack]

91983

That needs framing and hung on a wall.

[Larry Gibson]

As usual, Doc has it down.

Larry Gibson

[MBTcustom]

91983

Alright, they say a picture is worth a thousand words, but could you please explain how you did that while maintaining proper cadence? I would be willing to bet that was an iron mold yes? That would certainly give you a little dwell to work with? You had a machined sprue plate though which leads me to think it was a modern mold yes? Perhaps an Accurate Mold?
There: I'm sitting in the chair over the tub of water. Care to throw a few baseballs? LOL!

Full Mold Jack: He does have them framed and hung on his wall......seriously. And I got some of his boolits for XRF testing, Almost wanted to bust out the camera on those too! LOL!

Larry, I agree: he's the Doc for sure.

[Larry Gibson]

91983

Now that's the way an excellent cast bullet should look. Not rocket science and not at all hard to make them that way.

Larry Gibson

[Dale53]

1 - I use a hot plate and pre-heat my mold until just under casting temperature (one or two casts brings the mold to perfect casting temperature).

2 - Go to Target (my choice) or Walmart in the fan department (may be season dependent) and buy a manicurists fan (this is a six or seven inch
fan that women use to dry their nails). It costs less than $10.00 (I think I paid $7.00 at Target). I have mine permanently mounted so when I
fill the mold, I move the mold under the fan. The sprue sets in two or three seconds and I cut with my hand (I wear a welders glove and just
move the sprue plate with my hand). I get nearly perfect bases this way. The fan does a couple of things - it cools the sprue quickly to speed
up production AND it maintains proper mold temperature. I use multi-cavity molds almost exclusively and they have a tendency to overheat
when running at production rates. This eliminates having water around my hot pot (I have been visited by the "Tinsel Fairy" in the past when
water was around the molten metal[smilie=1:). There is an additional benefit - my pile of bullets are cooled by the moving air from the fan
and I don't have to wait to move the finished bullets inside (I have a separate utility barn with a dedicated casting station). Removing minor
aggravations from the process is helpful to no end.

FWIW
Dale53

[cbrick]

The boolit picture is SAECO #382, a 150 gr PB SWC iron mold completely stock including the sprue plate. The alloy is clip-on WW +2% Sn. I don't know how old this mold is, I bought it used from John Adams after he retired and sold SAECO to Redding. I bought a few other molds from him at the time plus the lubrisizer that SAECO used in their shop, my first Star. Hhmmm . . . Why would SAECO be using a Star instead of a SAECO lubrisizer? Interesting huh?

I already told you how it's done (see post 17, this thread) and you responded with "Tricks are for kids", see post 23.

I'll add to Dale53's post, I too use a fan for cooling the mold depending on room temp & if it's needed. Be sure that if you do use a fan that your not blowing air across the top of the melt, this will cause much faster oxidation.

Rick

[detox]

I see a picture of ONE good bullet (not perfect, but good). What percentage was culled during that casting session?

[cbrick]

The point I was trying to make is that unlike a situation where that blemish was located on the driving bands, if instead it is located in the center of the nose, or the center of the base, that is the safest place for a blemish to exist. Am I wrong?

Your kinda wrong yes. The base of the boolit steers the boolit therefore ANY defect of the base is more severe than the same defect elsewhere on the boolit. With your combination of offset sprues and the holes from the sprue tearing (your pictures) would make it unstable. Hopefully those are very short range boolits where it would make considerably less difference.

Again, a defect is a defect whether or not you cover it up so that you cannot visually see it. It's still there and it's still a defect. How much of such defects your willing to accept depends entirely on what your trying to accomplish and what your willing to accept.

Rick

[MBTcustom]

you responded with "Tricks are for kids", see post 23.
Rick

Just for the record, that was just a joke in response to "Silly Mod", like the classic breakfast cereal commercial: "Silly Rabbit, tricks are for kids."
Just a joke.

My dad used to walk up to me struggling with an engine that wouldn't run, and profoundly state "Son, your problem is simple. It's either an issue with air, gas, or spark."
Thanks dad. LOL!

All I can figure is that you must wait to a certain time after the puddle is made to cut the sprue. That would make me think that it would screw up my casting cadence, because the mold is cooling while I'm sitting there holding it waiting for the opportune time to cut, but maybe not because the mold is still full?
Hmmmm, a few experiments are in order.....

[cbrick]

Well, I've never done a cadence count to open the sprue. When it's ready and I'm paying proper attention I open it. For many years now I have done it much as Doc described in post #29 gloved hand and all, I don't normally cut a bevel on the inside edge of the blocks though.

One thing that many seem to over look is sprue plate temp, it is every bit as important as proper mold casting temp. Once the mold is at proper casting temp including the plate it's important to keep the plate hot by pouring a very generous sprue puddle. During a casting session the sprue plate spends a fair amount of time sticking out in the air, it does not have the mass of the blocks, even the outstanding MP and NOE plates, and cools fairly quickly. Pour a very generous puddle and look at that puddle not as pouring lead but rather pouring heat.

Rick

[cbrick]

I see a picture of ONE good bullet (not perfect, but good). What percentage was culled during that casting session?

That picture is at least 15 years old, I apologize for not remembering how many culls there were in that casting session. I can assure you though that if the boolits are for match shooting I am anal about the boolits and in particular the bases. At the time that picture was taken I was using those boolits for NRA Hunters Pistol 100m targets in a Marlin 94 357.

Since you feel that boolit isn't perfect you are of course completely free to do better.

Rick

[detox]

No cast bullet is perfect, but you can get close. Good job cbrick:wink:

[cbrick]

Hmmmm, a few experiments are in order.....

I know that you have been resisting this though I don't know why but something that you can experiment with is adding 2% Sn to your WW's. You said that you are using 50/50 so add 2% Sn to the WW before mixing it or add 1% Sn to the blend. Rick thinks you will be pleasantly surprised and a happy camper. After all, we do want happy Mods don't we? :mrgreen:

Rick

[a.squibload]

91983

That was machined from platinum by a jeweler then sandblasted
for days with talcum powder...

[MBTcustom]

I know that you have been resisting this though I don't know why but something that you can experiment with is adding 2% Sn to your WW's. You said that you are using 50/50 so add 2% Sn to the WW before mixing it or add 1% Sn to the blend. Rick thinks you will be pleasantly surprised and a happy camper. After all, we do want happy Mods don't we? :mrgreen:

Rick

You should have gotten me 2 years ago when I was running all my alloys with 5% tin (I even tried paper patching alloys that were 35%Sn which actually worked pretty well).
I'm proving a theory to myself by leaving the Sn out of the mix except what is in there to start with. Once I'm satisfied I know it's personality, I'm going to start ramping the tin back up......slowly, and observing what changes take place.
I promise I'll have my head out of my butt by this time next year, one way or the other!

In the mean time, thanks for bearing with me! As you can see, I am not some super educated, uber perfect caster, but I'm changing that. I feel that I never got a good, comprehensive groundwork laid in my castboolit education, and I don't think I can progress (truthfully, I refuse to progress) any further until I satisfy myself with some basic truths about this sport.
It's a frustrating yet necessary thing for me right now, and I am trying to start over from the beginning.
Anyway, sorry for the thread takeover. Carry on!