First MiHec (358156) mold casting session

[DeadWoodDan]

Got around to casting my first MiHec mold 358156 . Preheated the mold on hotplate and ran WW alloy with tin solder added at 750. Took a good 5 sec. for the sprue puddle to solidify so i know mold was hot. Was running with the HP pins. First four dropped perfect, little frosting, couldn't believe it. After that it went down hill. Dropped close to 100 pcs with only 15-20 good ones.

1) boolits dropped right off pins when they were pushed out. Two pins slide in/out easily. Was curious if others had to "polish" the pins to have them move more freely?

2) the base on two of the four would not fill out. Tried a few different techniques but always same two cavities.

From reading other posts, i'm wondering if I wasn't keeping the mold hot enough and casting fast enough? Was curious if there is a sticky on casting with brass molds tips and techniques?

Thanks
DWD

[Maximumbob54]

I have to do the hot plate at the medium setting and I don't bother to start casting until the lead is at least 800. I've not had to polish pins but I did pencil a set of them and I guess it helps some. I just resort to giving the bolt through the mold handles a tap or two and they pop right off. And yes, you have to cast fast as that brass just lets go of heat in a hurry. Don't stop to admire, just pour, pause, snap, dump, and pour again. Every time so far I've had problems it's been fixed because something wasn't hot enough.

[Beagle333]

My suggestions:
Are your pins just a little loose? Usually until break-in, it helps to leave MP pins about 1/2 turn loose (just finger tight) so they can self-center and slide easily. Also for base fill-out, is your sprue plate too tight? I don't like mine to swing completely freely, but it shouldn't take but a slight flip (when the mold is empty) for it to move.

[Buzz64]

358 sized mp molds cool quickly (take a lot of heat to keep at optimum temp). Run your melt about 775 to 800 after your hot plate warm up. Then be sure to leave a good spru puddle on top - should take at least two seconds for the last spru to solidify. If not all is too cool. Agree with the rest of the above for other fixes.

[dragon813gt]

You don't have to run the melt as hot as suggested. I used to think this w/ MP molds. I figured it out eventually. It's all cadence. Every hot plate is different so I can't suggest a setting. I set mine to where the first sprues take close to ten seconds to solidify. Each successive pour takes less time until I get it down to a five count. I run the lead between 715-745. The smaller the bullet the higher the temp. And once you're up and running just keep going. Don't stop to inspect anything. Keep the pace the same and you are fine. I don't speed cast and my pace is pretty relaxed. So you don't have to kill yourself.

As far as the pins not sliding. Loosen the stems up some. I never fully tighten mine. It doesn't take much loosening to get them to fall under their own weight.

[Buzz64]

Deadwood,
Try the above advice (all of it) and please post what works for you. Might help others in the future with the same "new to mp molds' question.

[DeadWoodDan]

Second attempt went better. Loosened up the pins as instructed so they would they would go in/out on there own and worked perfect. Also what really helped was i adjusted the flow rate on the Lee bottom pour and held it as close to the spout as possible, this really helped on fill out and getting good bases.

Had the mold on the hot plate and HOT before starting. First pour took 15secs before sprue would solidify. Second one i got in a hurry and opened to soon. The lead smeared and I believe i got some tinning. It would not come off after casting a few hundred boolits.

Let this mold cool and cast with some other molds. I switched between the deep HP's to the hex shape pins. Everything went good second time around also once i got the rhythm again.

Wish i had a bigger pot, once i get going it seems like the pot is 75% gone, but a nice pile of boolits. Now to figure out the whole tinning thing.

Thanks for the help
DWD

[Crash_Corrigan]

I have a half dozen of those hex shaped pins on my Mihec molds. I lube the pins as they go thru the body of the mold with Bullshops Bullplate Lube on a toothpick. It keeps them moving in the body of the mold. I run the alloy hot, move fast and keep on moving. I do not stop to admire what I have made until the casting pot needs refilling. I dump my boolits into a 5 gallon pail of cold water and the sprues into a cardboard carton next to the casting pot.

Most times I give the metal prongs of the mold handles a smack with my hickory hammer handle to drop the boolits.

[cbrick]

Most times I give the metal prongs of the mold handles a smack with my hickory hammer handle to drop the boolits.

Crash, you started using handles? :popcorn:

Rick

[MtGun44]

+1 on loosening the pins a touch.

Bill