A little help?

[mktacop]

I have a 4-cavity brass mold that is a clone of the H&G 68. When I first got this mold, it cast beautifully at 670 degrees and boolits almost jumped out of the cavities when opened.

Now, I have to pour the lead at a much higher temperature, around 720, or I get incomplete fill where the blocks join up on two cavities (the others fill great, even at lower temps), and the boolits don’t want to drop from the mold (1 cavity in particular).

The alloy I’m using is the same, I’m still pre-heating the mold on a hot plate set to the same setting. Everything else is the same……but I’ve had to make the changes listed above to get decent boolits.

Has anyone else had a similar issue, and what can be done to remedy it?

[Ben]

You may benefit from a 2nd cleaning. Sometimes some of the cutting fluid will seep from the pores and it will take a 2nd cleaning to get everything back to normal.

As to the bullet sticking, this will take care of that problem also :

http://castboolits.gunloads.com/showthread.php?t=47669

[geargnasher]

If it's a Mihec mould, your vent lines are probably getting plugged up right at the edges of the cavities. If you go over that area with a 10X loupe you'll see a brass burr at the edge of every vent line, and these can trap microscopic bits of lead over time. Take a razor blade and carefully clean each vent groove out at the cavity edge, then make sure you don't have any burrs on the cavity itself.

Also, what you're describing can happen with oil contamination like Ben suggested, or by simply not running the mould as hot as you did before, as sometimes happens on a cool or windy day.

Gear

[David Sherman]

You might try smoking the mould. Light a wooden match and pass it under the cavities so that a littlr smoke deposits on the metal.

Good luck. David

[mktacop]

Thanks gents!

geargnasher, it is a Mihec mold, so I'll give it a check as you described.

[geargnasher]

You might try smoking the mould. Light a wooden match and pass it under the cavities so that a littlr smoke deposits on the metal.

Good luck. David

I hope you don't teach that to your casting class!

Gear

[MBTcustom]

Brass molds are hard to get up to temperature sometimes. Check the vent-lines, clean it with carb cleaner, and run that mother like a rented two dollar mule till you get frosty boolits then slow down a little to get them to start dropping smooth and shiny. What you describe sounds like a cool mold. The melt temp and the mold temp are two entirely different things. The melt effects the liquidity of the lead, hence the ability to fill the cavities, and the mold temp effects the size and quality of the boolits. You change the melt temp with the dial, and you change the mold temp with the rate of casting. The good news is that once you get a brass mold up to temp, it holds it much better than aluminum.

You might try smoking the mould.
Don't tell them that. It is a misconception and it does nothing that proper casting technique wont do ten times better. I chased that goat all over Knob Hill and found it in it's pen.

[Echo]

I chased that goat all over Knob Hill and found it in it's pen.

Tim, that earns a

Way To Go!

[Jim]

I have to agree with Tim. It might work for others, but it sure didn't do anything for me. A good, proper cleaning when the mold comes out the box, get the alloy and mold up to heat and the boolits practically jump out the mold for me.

[MtGun44]

Don't smoke the mold, it is a messy and unnecessary thing. Never saw it make any
difference other than making the boolits a bit smaller. As gear said - look for burrs
or vent issues.

Check for too tight a sprue plate, it should swing freely, a lot of venting occurs at the
base between the cavity and the sprue plate.

Bill

[mulespurs]

You have asked a question that I have been frustrated with but was afraid to ask.
I don't understand why oil contamination would make a bullet stick if that is the cause but I do have a pain in the butt problem with sticking bullets in my new Mihec 68 clone mould.
I was really frusterated with my new toy. I will try these solutions probably tomorrow.
I am glad that you spoke up.

[mktacop]

You have asked a question that I have been frustrated with but was afraid to ask.
I don't understand why oil contamination would make a bullet stick if that is the cause but I do have a pain in the butt problem with sticking bullets in my new Mihec 68 clone mould.
I was really frusterated with my new toy. I will try these solutions probably tomorrow.
I am glad that you spoke up.

I'm glad I could be of help! The edges of the cavities did have some buildup that has been carefully removed. I re-cleaned the mold and will check the sprue plate this evening.


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[geargnasher]

You have asked a question that I have been frustrated with but was afraid to ask.
I don't understand why oil contamination would make a bullet stick if that is the cause but I do have a pain in the butt problem with sticking bullets in my new Mihec 68 clone mould.
I was really frusterated with my new toy. I will try these solutions probably tomorrow.
I am glad that you spoke up.

Check something else while you're looking for burrs: Close the blocks and look down into the bottom of the cavities at the "nose". Do you see three little bumps on the meplat? Mine had three bumps in each cavity, two on one block and one on the other. They left distinct dimples in the noses of the boolits. These bumps tend to "lock" the boolits in the cavities. I used the eraser end of a pencil and fine valve-lapping compound to polish them down and the mould runs much better now.

Gear

[runfiverun]

you beat me to the ,look for a burr on the cavity edge.
all it takes is a slight roll over somewhere on the cavitys edge.

[41 mag fan]

Tried that smoking the cavities about 3 times. Figured out it's not the way to go.

Haven't smoked a mold since then, even the 2 cavity Lees don't get smoked.

[MikeS]

One thing I've often wondered, with so many folks talking about smoking the mould here I thought I might ask the question here: When you smoke a mould which is better, putting the mould in a pipe, or rolling it in cigarette papers? :kidding:

[Wayne Smith]

One thing I've often wondered, with so many folks talking about smoking the mould here I thought I might ask the question here: When you smoke a mould which is better, putting the mould in a pipe, or rolling it in cigarette papers? :kidding:

All those sharp edges are real hard on the papers! The answer has to be obvious.