Sharp Edges & Mold Fill?

[davidheart]

Howdy, I know this must be an easy one for some of y'all so that's what I'll ask here!

Today I was casting some pistol boolits with my scrap lead. Mostly WW with a little tin added. 20lb pot heated to 750+/- degrees. I was using a lee 158gr DC mold (357) and a lee 175gr DC mold (40). Both molds were cleaned prior to use with carb cleaner & a toothbrush to remove any oil residue, etc. During my casting after the first few throws the 158gr would have sharp edges 80% of the time and the 175gr would have sharp edges 40% of the time. When I opened the molds before dropping the boolits I could see the molds were not entirely filled when round edges were present.

Why does this occur and how I could I stop it? Thank you!

[randyrat]

Clean and clean again possibly.. I use Bar Keepers friend (more of a fine polisher than a soap) and a tooth brush to help clean a polish the sharp edges, Works really good!
Alloy temp is not as important as Mold temp. Clean again and get your mold hotter..

[country gent]

A light chamfer along the top edges of the blocks may help with venting and fill out. I use a flat piece of brass with 600 grit sand paper to lightly bevel the top edge. ( a line 45* and .005-.008 wide on each side makes an extra vent line right under the sprue plate). If these are new moulds and this was the first use run a couple 3 more times to break in and develop the "patina" on them. Sometimes 3-4 heat cool cycles helps a lot also. Heat mould to 300*-350* and let cool slow 3-4 times.

[Yodogsandman]

Photos of bad boolits would help.

[TexasGrunt]

RTFM.

Lee tells ya what ya need to do. Here's a hint. It involves smoke.



Get a butane lighter, I like those barbeque lighters, and lightly smoke the mold.

[w5pv]

Use Kroil as a cleaner and from there on use a tooth brush and Kroil to clean molds you won't be disappointed after your molds reaches casting temperature.No smoking or other preparations necessary.

[JonB_in_Glencoe]

A light chamfer along the top edges of the blocks may help with venting and fill out. I use a flat piece of brass with 600 grit sand paper to lightly bevel the top edge. ( a line 45* and .005-.008 wide on each side makes an extra vent line right under the sprue plate). If these are new moulds and this was the first use run a couple 3 more times to break in and develop the "patina" on them. Sometimes 3-4 heat cool cycles helps a lot also. Heat mould to 300*-350* and let cool slow 3-4 times.
Yes, since the OP hinted at base fillout, this /\ ... /\ ... /\ is what I would try first.

other things to try:
-cast faster
-pour larger sprue puddle
-If bottom pour pot, try faster stream, then try slower stream..try different hieghts.
-then try pouring into the sprue hole differently...straight in, or hit the edge so it swirls around

lastly, when you say you add a little tin...what percentage?
COWW has 0.5% or less tin, and about 2.5%antimony...the best thing to have is balanced tin and antimony.
when I add Tin, I start by calculating 1%, then add that...if I don't get the results I hope for, I add another 1%.
But honestly, if the mold isn't a troublesome one, you should get good boolits without adding any Tin to COWW alloy.

as you can see, there isn't just one quick and easy answer.

[earlmck]

No matter how you have cleaned 'em, the first time you use a Lee mould you'll need to do quite a few throws before you quit getting the effects of whatever oil the Lee folks use in their manufacturing process.

If you are still getting unsatisfactory fills after 50 throws or thereabouts I'd try some different fill techniques. I'm assuming you are using a bottom fill pot? Use full contact/hold for each cavity for a while -- that'll get the dang things to fill!

[runfiverun]

practice.
just doing a few more sessions will get you up to speed.
stop admiring the boolits and just go after seeing them a few hundred times your eyes will go straight to where they need to be and you can get back to keeping heat built up in the blocks.
once you find the heat zone of the mold a cadence of filling, counting, and dumping will set itself into motion and your boolits will improve on their own.

[Beagle333]

I'm agreeing with casting faster. Cast like yer arm was on fire. Don't look at em, don't poke em and roll em around, don't see if the edges are sharp... just cast, cast, cast, and then you can look and see what effect that had. A lot of frustration with poor fillout and wrinkles and rounded bases can be directly attributed to not getting the blocks hot and keeping them that way. It doesn't take long for an exposed cavity to get cool enough to make a bad pour on the next fill.

[David2011]

You have my sympathy. I recently started a thread "http://castboolits.gunloads.com/showthread.php?331836-Unusual-flaw-on-boolits-from-a-Lee-mold" over the same .40 mold and have been casting this evening with a Lee 358-158 RF. I was getting sharp fill out but had a sort of circular flaw on the side of some boolits that turned out to be a venting problem. I usually pour down the centers of the holes but on this mold part of the solution was to pour to the handle side of the holes at a reduced flow rate. That seems to give the trapped air time to escape and allow a good fill. I also tried different alloys, melt temperatures and mold temps but none of that made much difference. I also experimented with timing from the time the pour was completed until I cut the sprue. Both of my molds are 6 cavity so my times probably wouldn't be useful to you. As the hold time before cutting the sprue was extended the pot needed to be hotter to prevent spout freeze. I'll be the first to acknowledge these are unconventional suggestions but these are problems unique in my experience to Lee molds.

I bought the .401-175-TC knowing it would be more of a challenge than the 2 cavity 170 gr Lyman it replaced but shooting 3,000 round or more every month a bigger capacity mold was necessary. It's been easier to use than the 358-158 RF, though. The mold has to be very clean, good enough for your mother-in-law to pass muster. Dawn, Barkeeper's Friend and a toothbrush will probably do a better job than highly volatile petroleum distillates for clean molds. Make sure the alloy is well fluxed, too. I need every advantage I can come up with when using Lee molds. The guys that use them all the time seem to have the best techniques.

Let us us know how it goes for you.

David

[davidheart]

Thanks for the input David. It sounds like you know exactly what I'm dealing with. Next time I cast I'll be sure to put everybody's suggestions to use!

[David2011]

Davidheart,

I'm continuing to experiment with the 358-158 RF. I've fought this mold for probably 2 years so decided to start over with it as if brand new. I cleaned the mold again with mineral spirits followed by lacquer thinner, Leemented it to polish the cavities and then gave it a good wash with Dawn and hot water. I put the recommended tiny chamfer on the top inside corners and smoked the faces of it. I went back over the vent lines with a sharp tool made from music wire. Smoking the mold helps see where I've worked and what still needed to be done. I could feel burrs at some of the intersections of vent lines so went over them from all directions until I couldn't feel any restrictions. I also very lightly scraped the parting line areas of the cavities to get rid of any burrs. This mold has never dropped boolits without multiple strikes on the hinge bolt so I was trying to fix that among other things.

After all that I cast some 20:1 (pure lead:tin ratio) which isn't an alloy I normally use simply because of the amount of alternative metals I have on hand; I just wanted to try something different. Boolits dropped better than ever but there's still a little tweaking to be done. In spite of lots of knowledgeable people telling me how fast I should be casting my best results were with about 3/4 second per cavity fill time by a timer and 10-15 seconds of wait time before cutting the sprue. Since mine is a 6 cavity mold you would need to cut the sprue sooner to keep the mold hot enough. I had far fewer fill issues than when pouring as fast as I could manage. The boolits were smooth with sharp corners and a nice shiny finish. The puddle was freezing in 4-5 seconds so the mold was not super hot.

Some of my results are not what I would have predicted based on past experiences with other Lee molds but I feel like I'm on a path to make this mold pleasant to use.

David

[Taterhead]

My DC Lee 175 40 cal vents poorly. Loosening sprue plate tension helped. Problem then became that the screw would work loose after a few casts. Good bullet, but I don't care for the mold. The other thing that helped was to pour a thin stream of led into the center of the sprue plate hole so that there was a place for air to eacape oit the top back through the sprue plate holes.