High reject rate. need help/suggestions

[BK7saum]

57515

[DLCTEX]

Heat up that mould. You are casting too cool. I preheat on an electric hotplate. May also need to clean the oils out, but a hot casting session will burn that out most times.

[220swiftfn]

Mold too cold, contaminated cavities, clean them out well, and casting faster should help.


Dan

[BK7saum]

Lost everything.

247 whisper mold with 50/50 COWW./PB. Pot temp 660-690. Sprue solidifies in 3-5 seconds.

[BK7saum]

http://i1229.photobucket.com/albums/ee467/BLK7mm/2013-01-03191205.jpg

[BK7saum]

What I'm getting is the circular rings or imperfections on the drive bands on one side of the boolit. I think the alloy is contacting one side of the cavity before the mold fills to the drive bands and forms a ring around the small piece of alloy already on the band.

Do I need to get really hot with mold? I try to pour straight down into mold but not much luck most times.

[BK7saum]

The bases are filling out well and all corners are nice and sharp. The boolit on the right is what I'm commonly getting. The others were probably at the beginning when mold was cooler but they still have the band imperfections I'm talking about

[462]

The bases are filling out well and all corners are nice and sharp. The boolit on the right is what I'm commonly getting. The others were probably at the beginning when mold was cooler but they still have the band imperfections I'm talking about


They don't look that way, to me. I see rounded and ill-formed bands and at least one base.

1. If you haven't thoroughly cleaned the mould, do so. If you think you've thoroughly cleaned it, clean it again.

2. Mould temperature is primary, alloy temperature secondary. Pre-heat the mould.

[GP100man]

Agreed , most molds have to go thru a couple of heat cycles to puge all the cutting lubes out of the pores of the metal & heat helps !!

Also , how ya lubing ya mold pins ??? Ya may be gettin lube migration into the cavitys ??

[BK7saum]

I cleaned the mold, heat cycled, and cast for about 5 hours with this thing.

If its oil or needing to be cleaned why are the circular imperfections are always only on one side of the boolit.

[BK7saum]

I'm lubing the pins with a very light touch of bullplate on a qtip.

I seriously don't see how that little amount of lube could migrate to the center cavity of a five cavity mold.

[BK7saum]

I've started preheating it on a hotplate. Only a couple of casts to bring up to temp with a Sprue solidifying time of about 4 seconds.

[BK7saum]

How much time should it take for a Sprue to solidify at proper mold temp. I wouldn't want to get it too hot to warp the mold. Should I shoot for 6, 8, 10 seconds?

[Shiloh]

How are you casting?? Bottom pour or ladel?? I think your melt is to cool as well.
If it is a bottom pour, I had accumulated crud clogging the spout. The stream was to slow. After cleaning with a piece os skinny wire, it improved tremendously. Some of my LEE molds need to be be cast hotter than others.

Shiloh

[BK7saum]

I'm casting with a bottom pour lee pot. I will try casting with a faster flow. Its not wide open. When it was I had lead everywhere.

Thanks everyone. I'll try a hotter mold, with a hotter melt, and a faster flow.

[MtGun44]

Standard newbie answer: Too cold and/or too dirty.

Heat things up - cast faster to bring mold up to temp, do NOT inspect boolits for first 20 fills or so, just
pour, cut, dump, pour, cut, dump - as fast as you can go. Once mold is warmed up and casting well,
you can slow down a bit and control the mold temp that way.

Clean the mold: scrub the cavities with a toothbrush and Comet. Will not hurt anything and will very quickly,
20-30 secs of cleaning is all that is needed, completely clean the cavities.

Bill

[R.M.]

Don't worry about lead spilling over. Keep an ingot mold or other such pan to catch the overflow. In time, you hit that happy medium where the flow is fast enough, yet not spilling over.

[44man]

I am no help at all for bottom pour being a confirmed ladle man. I cast with the pot on 750* for everything except pure when I go to 800*. The hotter lead allows me a slower casting pace.
I heat the mold to 500* in my little mold oven on a hotplate. First boolits are perfect. It is nothing to dump a 20# pot without a reject even if I have to step outside to wee now and then. I can use two molds at the same time and have gone to three but getting the other molds up to temp is a bother. I set a mold on wood as I pour another and go back and forth.
Time for the sprue means nothing so don't count, go by look. You want to cut the sprue, not smear molten lead. I actually just swing my arm and the mold 4 or 5 times before cutting, that cools the sprue just right for me. And yes, I use a heavy stick to cut with tiny taps. Don't use a big whack to cut.

[bobthenailer]

How much time should it take for a Sprue to solidify at proper mold temp. I wouldn't want to get it too hot to warp the mold. Should I shoot for 6, 8, 10 seconds?

with a 5 cavity mould throwing 200gr+ bullets i would expect to wait at least 8 and up to 15 seconds before cutting the sprue when casting at 700 to 725 degrees pot temp and when the mould is up to proper casting temp. a hot mould makes good bullets ! and dont worry about bullet frosting .
also try different pouring speeds and you might try not pouring directly through the sprue hole ! just a little off center so the stream will sort of swirl around . also pour large sprue puddles

[Charlie Two Tracks]

I am no master caster by a long shot but here are some things I ended up doing to get up and running.
I have my pot (well anchored with 4 screws) at a height that I can see the spout easily. I have my mold so it is about a half inch below the spout. I keep the lead at 700 to 750 depending on what I am casting. I let the lead hit the mold on the left side of the cavity and swirl in. I have a damp cloth so I can cool the sprue plate if it gets too hot. I don't know if you have cast for a long time or not but it took me a fair amount of time to get boolits that looked good. There is quite a bit of things to remember all at once. My temperature would vary, the amount of sprue would vary, the speed of the lead coming out would vary depending on how I lifted the handle on my Lee 20. I just decided to cast away and not worry about the end product. After quite a few Folger cans of boolits that were wrinkled, varying weight and width, frosted and too cool, I started casting good boolits and developed a method that works for me. By having the spout of the bottom pour in plain sight, I can set the mold holder at an angle that will allow the lead to flow down into the mold the way I want consistently. I had to relax and enjoy just casting. The guys here gave me all kinds of good advice.

[BK7saum]

I cast several hundred this evening. Ran pot at 740-750 and my reject rate went way down.

Thanks everyone. I can't cast fast enough to have heavily frosted boolits. Outdoor temp around 40 cools things off too fast.

But I'm happy with the improvement and know where to go from here. Thanks again everyone for all your help.

Brad

[Calamity Jake]

No one said anything about the venting, SO check the vent lines they need to be clear.

[41 mag fan]

I cast several hundred this evening. Ran pot at 740-750 and my reject rate went way down.

Thanks everyone. I can't cast fast enough to have heavily frosted boolits. Outdoor temp around 40 cools things off too fast.

But I'm happy with the improvement and know where to go from here. Thanks again everyone for all your help.

Brad

Right theres probably more of the answer than is known.
You casting outdoors and the mold will cool real FAST if left open to long in that temp. You'll have to cast fast, and maybe the first 2 to 3 casts leave the casts in the mold after cutting the sprue for an extra 3-4 sec. this helps heat transfer from the lead to the mold. Then every 10 -15 you might do it again just to make sure the mold stays up to temp.
6 second the sprue to solidify is the rule, anything slower esp, being outdoors, will cause rejects. Also being outdoors cast with a bigger sprue puddle.
If using a hotplate to preheat mold, try using something like a big green bean can to place mold in on hotplate, similar to an oven.

[**oneshot**]

I am guessing an aluminum mold here. I have several, and all have gone through a cleaning and several heat up/cool down cycles before casting great boolits. I set up to cast another mold and take my new mold through it's prep. Pre heat mold, then cast about 20-30 cycles letting the sprue cool just enough to not smear. On the last cast, cut the sprue and set the mold off to the side to cool. I cast the other mold til I need a break/refill pot, then I do the new mold again. I continue this until I am done casting, except the last thing I do before shutting down is the new mold one last time dropping the boolits out on the last cycle.

[kweidner]

Swirl with the lead like others said. It makes for great boolits. Remember ww lead is not gonna be super shiny. Look for proper fill out and no round edges. watch your driving bands. They will tell you when things are getting on the hot side.

[williamwaco]

What I'm getting is the circular rings or imperfections on the drive bands on one side of the boolit. I think the alloy is contacting one side of the cavity before the mold fills to the drive bands and forms a ring around the small piece of alloy already on the band.

Do I need to get really hot with mold? I try to pour straight down into mold but not much luck most times.

I agree with the others that this looks like too cold or oil in the cavity. since it is in the same place every time, I lean towards oil.

BUT.

That can also be caused by splashing if the stream is too fast and zaps straight to the bottom of the mold and splashes back up.

If running hotter doesn't cure it, try tilting the mold very slightly to one side and allow the stream to barely hit the side of the sprue hole.

Running hotter means at least three to five seconds for the sprue to harden.


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