Why is this happening?

[Paulinski]

I was casting today using Miha brass moulds.

I bought a hot plate and pre-heated the mould on a medium setting -

Got the pot warmed and poured - seems the med setting on my hot plate is to high as the moulds were too hot.

My 125gr 9mm mould was giving me most trouble - one the spruce was cut it was really hard to open the mould (i lubed the spruce plate and alignment pins with bullplate)

The bases of the bullets were sticking. Any idea why?

http://i39.photobucket.com/albums/e193/Dragnaath/IMG-20110509-00078.jpg

http://i39.photobucket.com/albums/e193/Dragnaath/IMG-20110509-00079.jpg

I disassembled the mould after scrubbed with bronze brush hopefully next time it will work better.

[btroj]

Looks to me like the HP pins are pivoting the bullet nose put of the cavity which is then wedging the base into the cavity. Try opening the mold right side up the turning it over to dump the bullets? Or give the handle pivot a tap with a stick as you open the mould, might get the gilet to come out of the cavity more squre to the blocks.

[Paulinski]

I don't think its pivoting as its seems to me the base is getting stuck to the mould...

[.45Cole]

I'm not an expert, but if it was mine I would look into
1. burr or something on the cav, although it would be rare for there to be 2
2. maybe the mold isnt as hot at the top as the bottom, and sprue plate is cooling the top down
try smoking the part where the mold is catching

[mpmarty]

Don't smoke it, use it. Keep on casting and you may well find the problem just "goes away".

[Paulinski]

I tried again few min ago - now its only one cavity doing it...

I hope the mould is ok as this is my fav 9mm mould...

[cbrick]

No, don't smoke the mold!

Smoking a mold does three things. 1> It attempts to cover up a problem. 2> It helps block the vent lines. 3> It helps carry on one more old wives tale.

You just spent your time getting it clean right? So why would the first thing you do after that is get it filthy?

You'll be be much better served by figuring out what the problem may be, assuming there is one, as opposed to an attempt at covering it up.

Rick

[theperfessor]

Maybe its just the photo but it appears as if the base of the bullet is rounded off and not sharp.

A couple of suggestions:
Make sure the sprue plate is loose enough to vent properly. This will help keep the top of the mold and the sprue plate warmer.

There are still burrs somewhere in your mold. The one that is working better has had some of the burrs knocked off by use. I'm convinced that a "well broken in mold" is simply one that has had all the oils burned out of it and all the burrs knocked off the edges of it, whether by use or by a deliberate act of deburring.

[Moonie]

I found my Mihec mold casts better with the sprue plate loose, as in will pivot on its own when empty and rotated.

[3006guns]

My only comment is to NEVER use a bronze brush on a brass surface...period. The bronze is considerably harder than the brass and can scratch it, causing more problems than you've solved.

[geargnasher]

I know you don't want to hear it, BUT YOUR MOULD IS TOO COLD, no matter what you think. Those boolits are shiny. Unless they are pure lead, or a weak lead/tin alloy, they are too cold. The bands aren't filled out very well, and the noses around the HP pins are barely sharp.

Get the mould hotter, that means preheat it and CAST FASTER. Four pours a minute with that bulky, brass, Miha mould.

DO NOT smoke the mould.

DO NOT clean it with a bronze brush, get it hot enough to soften the lead and work it over with a wooden stick and a dry cotton rag.

Try closing the SPRUE plate, not the "spruce plate", after you cut the sprues but before opening the blocks, that will keep the bases square to the blocks upon opening.

Gear

[Doby45]

I know you don't want to hear it, BUT YOUR MOULD IS TOO COLD, no matter what you think.

Exactly what I was gonna say. You can see for a fact that the bands are rounded. I cast that same boolit with that same mold and those boolits should be ever so lightly frosted and they will fall out like you greased the mold with butter.

[Paulinski]

Thanks for the input everyone. I will try tonight and get the mould hotter.

[475BH]

When you are heating the mold, place it w/ the sprue plate down (on the heater).

[ChuckJaxFL]

The bases of the bullets were sticking. Any idea why?


I have that mold, and had that identical issue. I ran the mold TOO hot, and still had the issue. To me, it appeared that the groove is deep enough that if the bullet tilts slightly, it grabs the mold on the way out.

My solution, so far has been to set the pins up opposing each other. I'm still deciding if it's a long-term solution, but it's looking promising.

[BABore]

You need a really hot mold when using multi-cavity HP molds. It also helps to tilt the mold toward the side the pins are attached to when you tap the handle hinge and open the mold. Tilt it the opposite way and the base trys to stay with that side while the HP pins pull the nose the other way. As you open the mold, make sure the base stays with the pin side.

[Paulinski]

My only comment is to NEVER use a bronze brush on a brass surface...period. The bronze is considerably harder than the brass and can scratch it, causing more problems than you've solved.

Dully noted sir..

[Paulinski]

I also found out that one set of pins would not come outta the mould without tapping them out with a punch.

Maybe they were bent? I swapped the penta pins and they slid in no problem without any issue.

I tried it again with more temp and the issue persisted although not on every opening. I'm going to be casting solids for a while for my 9mm AR so maybe some use will make the issue go away...

[captaint]

I think the tight pins is quite common. Doing what you did will often work. Sometimes a little adustement is beneficial. Do lube them lightly with Bullplate. Lightly.. The tolerances there are very close. enjoy Mike

[runfiverun]

see ba bore and gear gnashers post's above.
re-read them again.
then one more time.
inspection/technique/temp will be your keys to happiness.

[rattletrap1970]

I have never smoked a mold, and I've never had a problem as long as the mold is up to temperature.

[MtGun44]

Minor point - but you DO know that the metal pivoting plate is the SPRUE plate,
not a "spruce" plate - RIGHT?

I wouldn't have said anything but you used the term several times in the post, not just
a single typo. I continue to wonder where the term ever came from, but it keeps popping
up again and again.

Bill