New MiHec Mould, how do I condition it to get it ready?

[drfroglegs]

I was surprised there was not a sticky explaining how to clean, condition, and lube new moulds to get them ready for casting.

I have 3-4 Lee aluminum moulds that I just cleaned with carb cleaner and lubed with BullPlate.

Well, I just bought this GORGEOUS MiHec mould and want to make sure I treat it like the fine lady she looks like. I've scrubbed off the cutting oil with a toothbrush/Dawn, then rinsed in Acetone and let air dry.

Now.. I've read around that some people put it in the oven at ~400F for ~hr, then take it out for an hour, then put it in, etc... to oxidize the brass (so it doesn't oxidize while casting).

This is what I want to know, what is your procedure for "conditioning" the brass mould in the oven to properly oxide it. Thanks for your feedback.


Pic of said woman:
http://i1303.photobucket.com/albums/ag158/drfroglegs/20141205_212740_zps5fa181c0.jpg (http://s1303.photobucket.com/user/drfroglegs/media/20141205_212740_zps5fa181c0.jpg.html)

[btroj]

I scrub mine with Comet and water. I then heat it on a hot plate and cast. Oh yeah, put some sprue plate lube on the top of the mould, alignment pins, and on the outside of the pins that go thru the block for the HP pins.

[Beagle333]

I was surprised there was not a sticky explaining how to clean, condition, and lube new moulds to get them ready for casting.



The new improved Google search bar is great. It'll find many threads on nearly anything. 'Much better than the old search feature.
http://castboolits.gunloads.com/google.php?cx=partner-pub-6216953551359885%3A1942134700&cof=FORID%3A9&ie=ISO-8859-1&q=prepping+mihec+mold&siteurl=castboolits.gunloads.com%2Fforumdisplay.ph p%3F18-Swappin-amp-Sellin&ref=&ss=4043j1365015j19&sa.x=0&sa.y=0

[wlc]

I scrub mine with HOT water, Dawn and a toothbrush. Let dry then hit it with the carb cleaner just to make sure. Heat it up on the hot plate and go to casting. I use bull plate on the top of the blocks, under the sprue plate and the alignment pins. Mine usually always start casting good bullets within a few drops.

[drfroglegs]

I scrub mine with HOT water, Dawn and a toothbrush. Let dry then hit it with the carb cleaner just to make sure. Heat it up on the hot plate and go to casting. I use bull plate on the top of the blocks, under the sprue plate and the alignment pins. Mine usually always start casting good bullets within a few drops.

I just wasn't sure about heat cycling.

I pretty much follow your procedure to a T, but have never owned a brass mould.

I keep reading about people heat cycling these moulds; is that even necessary?

[Beagle333]

I cannot tell any difference in one that I cycle and one I do not. Apparently my oven doesn't assist me in "breaking one in" at all. YMMV.
Casting definitely gets em going though. By the 3rd session.... it is running like a real champ.

A lot of people like to smooth out the face on those penta pins a bit though. I can get em to drop well once I get everything hot enough, but with that rough pattern on them they can grip like a bulldog until they hit the magic temp.

[JonB_in_Glencoe]

...snip...
Now.. I've read around that some people put it in the oven at ~400F for ~hr, then take it out for an hour, then put it in, etc... to oxidize the brass (so it doesn't oxidize while casting).

This is what I want to know, what is your procedure for "conditioning" the brass mould in the oven to properly oxide it. Thanks for your feedback.

Clean shiney brass molds can get tinned. Not everyone has an issue with tinning. I think the issue is how hot you need to run your mold...some require more heat, especially HP molds. And the boolit design...molds with narrow points at the Lube groove area seem to be an issue for me.

I recommend reading this thread.
http://castboolits.gunloads.com/showthread.php?169575-Brass-Patina-Recipe

[longbow]

Okay then, my procedure for casting with a new brass mould is to wipe it off with a paper towel, pre-heat and cast. That simple!

My personal belief is that pre-heating is the key and with brass moulds, keeping the mould temperature HOT. That means cast at a steady cadence and don't stop to examine boolits as they drop. The mould needs to be run steady and kept hot, especially HP moulds.

As for the tinning, I have never had a problem but then I tend to use range scrap or wheelweights and do not usually add tin. Apparently if there is "extra" tin in the alloy, you can get tin oxides forming and building up on the mould. There are a few threads about creating an artificial patina on brass moulds to discourage "tinning" of the mould.

I use sprue plate lube on the sprue plate pivot, mould top an alignment pins and pre-heat until I just start to see the sprue plate lube smoke. That is slightly too hot and once casting the mould will cool a bit but that works for me with very few rejects even from a new mould.

If you add tin then the tinning issue may be a problem and a patina may help keep tin from building up on mould faces.

Most of my moulds are iron but I have two Mihec brass moulds and one Accurate brass mould and all three are still shiny and cast beautifully with no tinning problems and no rigorous clean up before use. Oh, and I oil my moulds after use ! even the brass moulds because they have steel sprue plates and alignment pins. When I go to cast, my procedure is the same... wipe them off then add some sprue plate lube as required then pre-heat and cast. No brake cleaner, no scrubbing, no fuss, no muss.The Mihec HP moulds do like to be run hot in my experience though. Cast fast 'n steady!

YMMV

Longbow

[ballistim]

I saw someone in a previous thread a while back detail a method of breaking in a new MiHec mold & I've modified it a bit. I first spray everything - mold & all pins, etc. with spray carb cleaner, then I soak everything in warm water & use a toothbrush with Dawn dish soap & scrub, then rinse with hot water which dries off very quickly. Next I assemble the mold with the first pins I'll use to heat treat in the oven, most often the penta pins that I'm very fond of. Many have mentioned problems with the penta pins & I had sticking problems, too. Someone mentioned this before, but I found that using a small Craftsman ignition point file works wonders at getting rid of the rough tooling marks, & after filing I use a carpenter pencil to apply the lead / dry graphite to the pins. I then condition the molds by heating to 450 degrees in an oven for 45 min. then cooling down to room temp. & repeating this process 4 times.
I pre-heat every time before casting on a hot plate, makes a huge difference! Casting in a new mold for the first time I fill the cavities & cut the sprue, then I apply sprue oil (now using a/c ester oil after reading a post on it here). I coat everything while hot & especially the hinge pin and outside portion of the pins at the c-clips before releasing the first cast boolits. Several of the first cast I will drop into the sprue bucket until perfect boolits drop easily into a water quench bucket. I'll re-apply sprue lube as needed, but always with the cavities filled with lead. Many have listed the procedures that work for them, and this works for me. I always pre-heat molds on a hot plate before casting and this helps get perfect casts almost immediately on a mold that has been used previously after the break-in method described. I'm a bit superstitious & methodical (my kids say OCD), but I stick to what works for me which usually produces consistent results and avoids problems.

[Dale53]

I have a number of Mihec moulds in both brass and aluminum and I am a REAL fan!

I have learned that applying mould release just to the surface of the pins that form the hollow points solves the sticking problem, completely. The bullets just fall off with one tap of the handle hinge after the mould is opened and turned upside down. I open with a gloved thumb, by the way.

After you learn to operate these moulds, your production rises to the point of total satisfaction.

I DO lubricate all moving surfaces with Bullshop's sprue plate lube taking care to keep the lube out of the cavities.

When I pre-heat on the hotplate (I pre-heat ALL of my moulds) I am careful to keep the temperature of the mould just below proper casting heat - one or two cycles and the mould is up to temperature. DO NOT OVERHEAT THE MOULD AS YOU COULD WARP IT! By heating just under casting temp I am insuring that I won't overheat.

FWIW
Dale53

[dragon813gt]

Spray w/ carb cleaner to remove any residual oils.
Heat cycle three times in a toaster oven.
Take mold apart and lube everything that needs lubing.
Preheat on hot plate and cast away. Even w/ heat cycling they start casting better the more times you use it. It it's a HP mold you need to keep the pins hot. The penta pins are rough and don't like to release bullets. The large hollowpoint pins, if available, are typically the easiest ones to cast w/.

[CPL Lou]

I like to keep things simple, so here's what I do.
I spray the mould and pins (separately) with non-chlorinated brake parts cleaner.
I take a pencil to the penta pins and make sure I cover all the flats then assemble them into the mould, tightening them all the way, then backing one of the screws on each pin off by a quarter turn.
Place mould on hot plate to preheat while I warm up my pot.
Put lube on pin screws using a q-tip, then on the spruce plate and mould alignment pins. Wipe off excess lube with a paper towel.
Start pouring boolits !
I have somewhat over 25 of Miha's moulds and this simple procedure has always worked for me.

CPL Lou

[paul h]

Shot of carb cleaner to remove oils from machining, get it nice and hot, small drop of lube on the sprue pivot, hp slide rods and alignment pins and start casting.