Tips for reducing rejects

[F_L]

Help a newby out please. I just started casting 9mm 125 gr with a Lee 6 cavity mold. My mix is 50% soft lead (1%SN, 2%SB), 50% wheel weights, added approx 1% tin. Casting temp 700 degrees. I don't mind casting some rejects to get the mold up to temp, but still having problems with base fill out. I have better luck casting fast, getting the mold hot and bullets frosty. But still have almost 50% reject rate. I added more tin, still no joy. Is it technique? I have tried pouring slow. Tough to do with my home made bottom drip-o-matic. Tried pouring fast. Am I trapping air, more tin????

Any help is appreciated.
Thanks,
Fred

[jcren]

More tin may help, but base fill problems with Lee molds can also be due to clogged vent lines. On Lee molds, the crosshatch machine patern serves as vent li es and can be easily clogged with excess lube or soot. If you have black or Brown residue on the mold mating surfaces, clean thoroughly with solvent and a toothbrush or the like. Just my experience, I'm sure others can help more.

[F_L]

Good info!
Thanks,
Fred

[Mk42gunner]

While I don't have that particular mold, I will say that the Lee six cavity molds I do have like to be ran hot and fast.

I'll second recleaning the mold and sprue plate, maybe even tracing some of the vent lines with a toothpick to make sure they are open.

A Lee six cavity with its three handles isn't the easiest mold to learn to cast with, but it is what you have. Make sure you are not putting any pressure at all on the sprue plate handle while filling the mold.

Robert

[wcp4570]

I'm sure you clean the mold before casting but if you didn't that may be part of the problem. I clean the mold real good and preheat it on a hot plate while waiting for my melt to get ready. Keep it moving after its making good casts.

wcp

[DrCaveman]

Sprue plate could be too tight. That caused a lot of rounded bases with my lee 6-cavity

[F_L]

Thanks for all the replies. Hopefully I will have some time to cast tonight. I will clean the mold and try a few tips and report back.
Fred

[Hickok]

I like to leave a pretty big glob of metal on top of the sprue hole so as the alloy cools it has plenty of metal to work with as it shrinks.

[btroj]

Rounded bases? File a tiny, and I mean tiny, bevel on the top inside surface of each block. I do a very light pass with a file on each block then Cast and see how it goes. If you get a small fin on the bullets you went too far.

[detox]

Sometimes I cast at temps of 800-900 degrees to get best fillout and prevent wrinkles. If turning the heat up does not cure base fillout, your sprue plate is too tight and flat.

[wallenba]

I don't know how cold it is in Texas right now, but I'm guessing it's cold. The others have covered most of the causes. I'd suggest getting the pot even hotter, up to 875*. Also, how close to the spout are you holding the mold? And how slow (metering rod adjustment) is it pouring? Remember, as soon as that hot mix hits the air, it's starting to cool and set up.

[F_L]

Update - Thanks to all the good info here just cast ~200 or so with much better results. I cleaned the mold, kicked the casting temp up to 775-800, and played around with the flow control. It went from very frustrating to enjoyable.
Thanks Everyone!
Fred

[jcren]

Congrats, now you have to work on your lead sources, once it gets fun, what you have won't last long!

[Animal]

I've got a high dollar Saeco and an expensive Lyman... None of them give as good of base fill out as my cheap Lee mold. I love my Lees to death. I did find that 800-850F was the sweet spot for good fill-out. I was reluctant to push the temp that high, but the Lee can handle it just fine.

[zuke]

More heat in the metal and mold, and a bit more of tin wont hurt

[Bullwolf]

Rounded bases? File a tiny, and I mean tiny, bevel on the top inside surface of each block. I do a very light pass with a file on each block then Cast and see how it goes. If you get a small fin on the bullets you went too far.

What btroj mentioned has been the solution for me with many a fussy mould that did not want to consistently fill out bullet bases.

Someone posted a great image explaining this that really helped clarify things for me. I don't recall who originally posted the image, though I suspect it was goodsteel, or JonB_in_Glencoe.

http://castboolits.gunloads.com/attachment.php?attachmentid=129571&d=1423101906

I wish someone had sat me down and made me do this sooner, it really made a few problem moulds I had, much more pleasant to cast with.

I've done this successfully using either a fine Arkansas stone, or a wood block with oiled 600 grit wet/dry paper. It doesn't take very much. Use a light touch - especially with an aluminum mould.

As with any metal removing endeavor go slow. It's near impossible to put removed metal back, if you've gone to far


If you get a small fin on the bullets you went too far.



- Bullwolf

[btroj]

Excellent photos. That is exactly what I'm talking about. I don't do it unless the mould needs it but some moulds I find just need the extra ventilation for give good bases.

[runfiverun]

go slow as in don't use a file use a whet stone to just break things over.
sometimes just getting the sprue plate to sit right is enough.
I always double look at that before I resort to breaking over the edge of the mold.

[Old Scribe]

Good info here. Inever knew about going over the edge of the mould. Ihave a problem Lee mould I will try this on.

[robg]

some molds like the lead to swirl around the hole in the plate some like the lead straight in,hight of pour can make a difference too

[Cmm_3940]

Get a cheap hot plate. Use it to preheat your mold, and set the mold back on the plate whenever you pause.

And always pour a BIG SPRUE.

[blikseme300]

Lots of good advice in this thread. I own and use about 30+ Lee 6-ganger molds and they do run better when hot and kept hot. I copied the sprue plate trough that the H&G gang molds have by machining a 3/8" half-round into the Lee sprue plate. This allows single stream casting and also keeps temperatures up as there is more mass to transfer heat. My bottom pour pot has a generous spout and allows a good flow and swirl in each cavity. I start pouring on the first cavity and move the mold to each cavity without stopping the flow. It takes longer for the alloy to cool before cutting than the pour takes. A mold with smaller cavities really benefits from this modification as the lesser mass of the boolits cannot keep the mold up to temp as easily as the 250+ grainers do.

129616

[F_L]

Results of yesterdays casting session.
129615
Rejects on the left. 8.2 lbs of the powder coated. I settled on a 750 degree casting temp and was happy with that. I may need to lower the mold temp a bit as the bullets went from frosty to slightly pitted. They all powder coated fine. There was a magic combination of lead and mold temp where everything was bright, shiny, and sharp. The quest for the perfect boolit continues.

Great suggestion on breaking the mold edges. I will file that recommendation.

Thanks,
Fred

[popper]

I use a knife edge to break the top edge of all my moulds. Just run the sharp edge across the mould edge. The mould & sprue plate need to be hot, not the alloy! Cold plate will freeze the sprue so it can't 'fill the base'. Pour some with the plate open and let set for a while to get the mould to temp, pour on top of the plate (partially open ) to heat the plate. Try pouring one hole first & cutting until each one gets up to temp. A 6x with cold sprue will break the handle.
bullets went from frosty to slightly pitted Is that slightly 'frosted' to greatly 'frosted' (Sb crystallized) or real pitting? Try dropping down to 720F & slow the pace slightly.

[F_L]

Congrats, now you have to work on your lead sources, once it gets fun, what you have won't last long!

I thought I was pretty well set with lead. In fact, I have an ad running in the Swappin/Selling right now to sell off some of my excess. I might quit bumping the ad.

[twc1964]

I had problems with excessive rejects in my lee molds . It seems that each mold has its preferences as to temp, etc. Most of my molds do well around 680 or so but one works best at around 725. Keep notes on stuff like this to avoid headaches in the future.

[runfiverun]

it's the combination of mold temp and your casting speed.
I run my HM-2 5 cavity 9m mold at a pot temp of about 680 I was also running it with a noe 2 cavity mold at the same time.
the noe was just hanging out at the verge of the greyish color zone and had a harder sprue [giving me a nice smooth cut-off] while the HM-2 mold was still running a softer easy to cut sprue the entire time.
the count between sprue breaks for each mold was 14 thousands.
I like running my NOE molds on the cold side and adding in another mold with greater heat retention allows me to do this.
if my mold temp started getting a bit low I just made three casts in a row to get it back up those extra 15 degrees again.

[EDK]

It's a poor day I don't learn something new here.

If you set the mould right side up on the heat source, the sprue plate may be colder than the mould. Steel takes a bit longer than aluminum. In effect, you're cooling the metal before it hits the cavity. Cutting a trough gets more heat onto the plate...and makes ladle casting a lot faster too.

[echo154]

NOT A LEE BUT A NOE….I noticed my Noe likes a small temperature variance also as anything from 700 down or 715 up are out of weight as far as I am concerned and either frost or wrinkle- Noe 4 banger 460 405….now the NOE 265RD I have in brass is much more forgiving……but much heavier.YMMV

[Jim..47]

I have the fill out problem with some of my molds too and will do the alteration, but will this also help steel molds like Lyman?

[Blackwater]

I think in the long run, learning to interpret and deal with mould and pot temp is probably the biggest key to consistency. Lead behaves slightly differently depending on its temp, getting a bit more fluid the hotter it gets, and making frosted bullets as it gets hotter as well. Balancing mould temp with the metal's temp is something you're just going to have to learn as you go along, but it sure helps to pay attention. Makes the learning curve shorter. Casting, if you want consistency and as nearly "perfect" bullets as possible, is mostly a story of keeping your focus and attention on process, technique and the technicall factors, like alloy content, temps, etc. that affect the results. As you go along, you'll learn to observe the things that matter and affect your castings. As with most anything else in life, experience is always the best teacher, but here at least, especially if you go back and read the stickies and look up issues that puzzle or frustrate you in the archives, you should be able to get an MA if not a PhD (if anyone ever gets that far in it) in casting with a minimum of trial and effort. It's not all about learning, though. Even when you know the factors, you STILL have to learn to focus so you can observe them, or preverably, observe them developing and ward them off before they get very far out of balance. Focus and attention are always the primary quantity that needs to be applied in order to get really consistent results.