Mi-hec Learning Curve Help me out

[wv109323]

I was on the GB of the 360 -158 gn. mold from Mi-hec.. I got my mold about a week ago and tried to cast with it tonight. I didn't have any success.
Mold is brass 158 gn. SWC with solid point and flat base and 4C. Pot is a Lyman 20 lb. bottom pour that is PID controlled. Mold is pre-heated on a hotplate. Lead temperature was 700 and then 725*. The lead is COWW mixed with range recovery from an old Bullseye pistol range. I also throw in some 50/50 solder.
The bullets were frosted on the middle crimping bands and wrinkled on both ends. I had a lot of wrinkles at 700 degrees and then cranked the heat up to 725. Still had some wrinkling and frosting in the middle got worse. I tried to run the mold as fast as I could. Also the bases never got perfectly square.
After about an hour of casting I ended up with no match grade boolits. i ended the sessions when the wooden handle came off my new Lee handles.
What do you suggest for success?
It appears I burnt the biscuits in the middle with the top and bottom still doughy.

[wv109323]

Let me add that I ran the mold through three heat and cool cycles a couple of days ago.

[btroj]

Wrinkles mean either a cold mould or oil in the mould. Scrub it with hot water, a toothbrush, and some Comet cleaner. Preheat on a hot plate or expect many rejects while getting the mould up to temp.
Rounded bases can be an overly snug sprue plate or a sign that you need to very lightly break the edge on the top, inner surface of the blocks. This allows for better venting of the top of the cavities. A very slight breaking of edge is all that is needed, too much will lead to slit finning on the bullet base.

[Oreo]

I cast with my Miha molds using an alloy temp up around 750°f. The mold needs to be kept really hot too.

Wrinkles sound like the cavities need to be cleaned though. The tiniest little smudge of sprue lube will cause pour after pour after pour to be wrinkled rejects.

[longbow]

You need to keep the mould hot, not just your alloy.

I pre-heat mine until the sprue plate lube just starts to smoke then start casting. That works for me.

Once casting keep up the pace to keep the mould hot. Don't stop to admire boolits or make little adjustments, keep casting at a fastish pace.

Watch the the tin addition too. Several people have had problems with "soldering" building up in cavities. I have never had that problem at all but I use straight wheelweights or range scrap with seldom any tin added.

Works for me anyway with two Mihec brass moulds and an Accurate Molds brass mould.

Longbow

[waco]

Wrinkles mean either a cold mould or oil in the mould. Scrub it with hot water, a toothbrush, and some Comet cleaner. Preheat on a hot plate or expect many rejects while getting the mould up to temp.
Rounded bases can be an overly snug sprue plate or a sign that you need to very lightly break the edge on the top, inner surface of the blocks. This allows for better venting of the top of the cavities. A very slight breaking of edge is all that is needed, too much will lead to slit finning on the bullet base.

Yeah. Scrubbing the mold with Comet or Dawn dish soap and a toothbrush, then boil the mold in clean water for ten minutes.

[geargnasher]

Brass loses heat about three times faster than aluminum, and I forget how many times faster than iron. Four-five pours a minute with 700-degree alloy will keep them happy, but don't slow down even for a second.

Gear

[JWFilips]

I had a somewhat similar problem with mine too. I didn't have any experience with Brass moulds and the folks here gave me good pointers.
I did still have to come up with my own method incorporating their suggestions . I had slightly loosed my sprue plate from the way it came to me ( I thought it was too tight) Then after much base fill out problems I tightened it back to where Miha had it ! Also during my hot plate heating before ( and also while ) casting I turned the mold over on the hot plate to lay it on it's sprue plate for awhile just before pouring. That fixed my base issues. Longer on the hot plate and quicker pourings fixed the nose issues and finally dropping my melt temps to 700 deg fixed my frosted middle issues.
& when you start casting, cast fast & don't stop. If I broke my cadence ( because of a sticky drop or otherwise keeping the mould open too long, I placed the mould back on the hot plate for a minute or so.
That worked for me ( but it took me 3 casting sessions to figure it out)

[btroj]

Some moulds are just like that. I have many that need a specific routine to stay happy. This is where observation helps. What is different in the method or rhythm when you get good vs bad bullets? Figure that out and adjust the system to produce only good bullets.

[Smoke4320]

as several have said here brass molds want to be HOT and I mean HOT .. my first one was a bear to learn too ..
Now I crank the hot plate to 600 degrees let it set of about 30 minutes before I start casting ..
98/2 lead is a 725-730 and cast fast..
If I have to stop for anything mold goes back on hotplate for a couple minutes, sprue plate down
that's the only way I could get good bullets but now I get them about 90+ % of the time
Got my first 300 Blackout kill with one Monday Morning .. :) :)

[detox]

I know what you mean. I had a similar experiance using an small single cavity aluminum mould. Using 16/1 alloy I could not cast fast enough to keep it hot or to stay on that sweet spot for good fill out. This same mould does OK with Lyman #2 alloy. You may need more antimony in your lead.

Have you tried using linotype lead? Something is wrong with your mould if you cannot cast with linotype. Linotype also has a higher percentage of antimony.

A properly designed Iron mould is more forgiving to different alloys because it dissipates heat slower.

I would try turning up the pot temperature to 800 before trying another mould or alloy

[DRNurse1]

Thanks. I have had difficulties like these, to, and this sounds like a good direction for fixing those problems.

[Forrest r]

Great molds, you'll get yours dialed in & be cranking out boolits in no time.

What I do:

I wash/clean my molds (store in oil) by letting them drain & then cleaning them with either brake cleaner, starting fluid or rubbing alcohol & let the cleaner evaporate/dry. Then I put them on a hot plate & set it to 5, it only goes to 6 so it's set hot. Then I turn on the lead pot to heat & the turkey cooker to heat/melt the lead to refill the casting pot. After around 20 minutes the lead in the bottom pour is ready to cast with.

I want the hot plate hot enough that when I'm ready to cast the mold puddles the lead on top of the spru plate. I lube the mold & pour the 1st pour. The puddled lead will take 10 to 15 seconds to harden on the spru plate & the boolits will come out frosted. After dumping the boolits out of the mold I'll wait around 10 seconds with the mold open, slowly cooling it & repeat until I get to where I cast boolits where it takes around 3 seconds for the puddle on the spru plate to harden.

I will start with the lead high 700+ degrees & work the mold (described above) & slowly turn the temp down until the boolits barely stop frosting. This helps me set the casting cadence for that mold, too fast the boolits frost, too slow they start to stick to the hp pins.

Start out hot & work the heats down instead of starting out cold & trying to bring the heats up. You'll have allot less rejected boolits & it will be easier to find your molds/alloys sweet spots. Just work on 1 thing & a time, mold heat 1st, alloy 2nd.

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[Crash_Corrigan]

I have had great luck in casting over the years by ignoring all the warnings about warped molds etc as I dip my molds into the molten alloy in the pot for about a minute or so prior to my first cast. This is after a very thorough cleaning of the mold with very hot water and comet and a toothbrush and then a boiling in water for 10 minutes or so. I do not oil my molds after use. I put them into metal ammo cans with some dessicant and here in Las Vegas the humidity has not been a problem.

After the mold has been dipped into the 750 degree alloy in the pot I commence to make my first pour. It may take the sprue puddle a minute or more to change color but when it does I smack open the plate and dump my boolits. Mostly they are perfect on the first pour. Like the OP said above it is easier to run too hot than to mess around with cooler temperatures. I use a RCBS pot without a PID controller. Just a plain RCBS thermometer works OK for me.

[jeepyj]

I also have benefited from this thread (well hopefully) I have been lucky enough to have a friend let me help him break in a Mi-Hec 4 cavity H/P and the first session this week went fair. I was in firm belief that I wasn't running hot enough. This thread is a testament to my belief. I usually have a bit of a frosty boolit but my first session with this mould mine were a more shiny than I used to seeing. My temperature was 715 degrees my hot plate was at 350 degrees same as run for my Lyman moulds. I will try some of the tips listed in this thread and see how the next session goes.
Jeepyj

[dragon813gt]

The learning curve is pretty simple. Hotter mold then you think it should be. Once the mold is up your rhythm will determine how hot the lead needs to be. There was only MP mold I couldn't get to run right. But neither could anyone else and I chalked it up to a bad bullet design.

[Jailer]

Sounds like you were right at the cusp of having the mold up to temp. You'll notice that when the center of your booilts are frosty and the ends shiny as you described. A little more heat in the mold and they would have started coming out great. You have to get it evenly soaked with heat.

Pre heat your mold to a slightly higher temp and cast faster. Pour a small sprue puddle so it will solidify faster so you can dump and pour again quickly.

You were close, just keep at it and you'll get there.

[cs86]

I have found that each mold acts differently. Not only to temp settings but the speed of the pour also.

Take note of the different sizes of molds. More material around the boolits means it takes more heat... at least to get the mold up to operating temperature. I have a Lee 2C .45ACP mold that heats very fast because it doesn't have lots of extra material. The bigger the boolit the faster the mold seems to heat up. I also noticed that pouring slower with this mold helps prevents wrinkles. It has a tendency to frost easier even casting at lower temps.

I have a 4C 9mm NEO that seems to take lots of heat. I can cast at 750 for a long period of time and not get frosting. Once I start seeing some frosting I back my temp down and slow my speed of casting to help. To me there is nothing wrong with a little frost.

My 1st and new 2C Mihec that I just got seems to cast nice at 700. If I go to high it tends to create fins on the nose. If I'm to low I don't get sharp corners or good fill out.

Sometimes to help get the mold up to temp I open the sprue plate and pour lead into the mold and puddle the lead across the top filling each cavity. Once it solidifies I drop the solid puddle with the bullets attached to the bottom as one unit and do it again until the wrinkles start going away. Just try not to get lead next to the pivot point of the sprue plate or it can get underneath, and try not to let it run over an edge or it can be hard to get it out of the mold. By doing this it's easier to pick up with gloves rather then several loose boolits and dropping it back into the pot.

Experiment and try different things: High heat, Low heat, pour fast, pour slow, add a little tin, when frosted open the mold and blow lightly on it and then cast again. Some find it a sin to smoke the mold, but I find myself getting the mold up to the proper temp of almost making perfect bullets and then smoking lightly. It may not be right according to others, but the bullet looks great, drop better, and it makes me feel all warm and fuzzy inside, so I do it.

I thought these turned out good.