Creasing in heavier boolits

[stanford]

I started doing some casting yesterday and everything went okay after a while when casting a .358 150g six cavity mold. Had some stumbling blocks along the way when I first started which got better as the mold got hotter and hotter. Today I wanted to do some more casting and that worked out pretty good too, I did some more .358 150g and most of them turned out pretty good. I then used the .358 105g six cavity mold and from the beginning to when I decided I didn't want to do anymore casting, every single boolit from every cast came out perfect from beginning to end.

I then tried my 45 cal mold and I had creases in the boolits, there were a few that were good but the bad out-weighed the good. I stopped with the 45 cal mold and went to trying the 308 rifle molds. This is where I am stuck, every single cast for the two rifle molds that I casted came out with creases in every boolit. I took my pid up to 810 degrees and put the molds on a hot plate but still nothing changed.

How come the lighter grain boolits are coming out much better that the heavier grained boolits? Anyone have any ideas? I get all my lead from the members here and I am not sure of what else I can try. After reading all the info dealing with the good and the bad I knew that I had all the areas covered. My molds are new and I made sure that I cleaned them out two weeks ago from the oil and whatever debris that was left in there after the manufacturing process.

Appreciate some feedback, I really want to see my heavier grained molds casting properly.


Thanks

[whisler]

If a bottom pour pot, could the flow rate be too slow for the heavier boolits?

[country gent]

creases or wrinkles? creases may be from a forieghn material in the moulds or not cleaned well. Also from moulds not properly alighned. Wrinkles are normally to slow a fill rate ( lead cools and starts to solidfy before fully filled), a mould to cool ( again lead solidifies before full), Trapped air in mould ( leaves voids where air is becoming trapped). Clean moulds with dish soap and water scrub into heavy lather with toothbrush and rinse well with hot water. With a sharp point ( scribe awl ice pick xacto knife point ) lightly clear all vent lines of any build ups or fouling. Are you using a bottom pour pot or ladle casting? Gravity pouring or pressure pours? Big sprue little sprue puddle? Pouring thru center of sprue hole or along edge. Sprue plate tight or loose? Sometimes lightly stoning a bevel ( .003 - .005 45* flat) along the tops of the blocks under the sprue helps alot with venting. Not alot you dont want to cause finning, just break the edge with a fine stone. Look for burrs and dings also.

[stanford]

Its a lee 20lb pot bottom pour. I was just chatting with one of the members and he said the same thing whistler and country gent said. Flow rate is probably too slow, and the lead is hardening before the cavity is full. I will look at the mold cavities with a magnifying glass and see if I can see anything strange. I did clean the molds with dish soap and hot water when I did clean them. After I saw the creasing I cleaned them again. Let me check and see if I see anything strange and also look at the vent lines.

Thanks guys...

[BK7saum]

Before spending too much time checking out the mold open the adjustment and increase the flow. As already stated, your flow is too cold for the mold temp. If you can cast faster and get your mold hotter, your current flow rate might still work.

I use Lee 20 lb pots and when the pot gets low I have to open the valve adjustment to compensate for decreased head pressure from a low pot.

Brad

[popper]

Mostly cast 308s ~ 720F. Cold mould, stutter/wrong flow rate or - cold drip. Too fast a flow and I get imperfect bases. If 810F is real, waay too hot, unless it's zinc.

[el34]

Mostly cast 308s ~ 720F. Cold mould, stutter/wrong flow rate or - cold drip. Too fast a flow and I get imperfect bases. If 810F is real, waay too hot, unless it's zinc.

In my experience 700-750 pot temp has covered everything. Around 800 is where tin or antimony start to oxidize and separate, don't remember which.

Also from my experience is realizing the 3 things- pot temp, mold temp, and flow rate ALL interact. If one is a little too high it will compensate for another being a little too low.

I found a way to measure mold temp between casts and learned that almost anywhere between 400-500 works fine. But that's with 700deg lead and a stout pour and who measures mold temp anyway. I like the pour adjustment to be as high as possible, just comfortably below the point where I can't shut it off quick enough to avoid lead spilling over the mold sides.

Those air vents are tiny scribes in the mold faces between the cavities. I first incorrectly thought they were evidence of cheap machining until I clogged them up by smoking the whole mold face. Live and learn.

[stanford]

I thought I would be able to give it a go again on Wednesday after work but something came up and I will have to wait until the weekend to try again. Hope the weather is good again and not hot.

[Echo]

Are the creases on the parting line? Could be burrs...

[Larry Gibson]

As mentioned the flow rate is too slow and the alloy is beginning to solidify too much before the cavity is full. As mentioned the spout stop has to be backed off for heavier pistol bullets and long, heavy rifle bullets. Also as mentioned the best temp to keep most alloys at is 710 - 730. At some point in most all furnaces the alloy temp will decrease as the alloy is depleted. Either add more alloy or adjust the thermostat to keep the alloy with in the right casting temperature range.

No mention of alloy used but alloys such as modern COWWs with very low tin content can give poor fill out resulting in wrinkled bullets. Adding a bit of tin can also solve the problem. With todays COWWs I arbitrarily add 2% tin with the resultant increase in the quality of the bullets, much lessor rejection rate, much less frustration along with a higher satisfaction being well worth the effort and minimal additional cost.

Larry Gibson

[el34]

+1 to Larry for first bringing up tin, its purpose is to weaken liquid lead's surface tension so that all the crooks and crannies get filled. A few pics showing the wrinkles might be helpful.

[stanford]

Looks like you can only add an image from a url, not even sure where to put it.. I thought about the tin after reading so many posts but I don't have any at the moment. Need to see who is selling some tin and get some.

Hope this pic works...

https://www.mediafire.com/folder/7xrrx238te6tk/Photos

[Yodogsandman]

Looks too cold to me. I'd get that mold heated up and increase the flow rate. That sometimes happens with a new mold before it's been heat cycled a few times, too. Maybe until all the manufacturing oils are burned out of the pores.

Wally mart sells non-lead sinkers that I believe are tin, for a quicky tin fix. 50/50 solder is 50% tin and 50% lead. Non-lead solder is about 99% tin and 1 % silver (check the label). Pewter is about 92% tin, 6% antimony and 2% copper and can be used as pure tin by weight.

[el34]

Where'd your lead come from? How was it described?

[stanford]

Where'd your lead come from? How was it described?

El34,

The lead came from here, don't remember how it was described. Once I give it a go again this weekend you will be the first to know. I think they said its going to rain this weekend.

[el34]

El34,

The lead came from here, don't remember how it was described. Once I give it a go again this weekend you will be the first to know. I think they said its going to rain this weekend.

Gonna rain til Christmas I here.

I don't think the alloy is all that critical as far as getting wrinkle-free boolits, or maybe I've just been lucky. I just saw your pic- that's pretty much the classic "something's not hot enough" look but in your case the slow fill theory might be right.

If you cast and dumped about a dozen or more cycles the mold should have been up to temp. And 800deg lead is certainly not on a cold problem.