How long to heat up mould?

[1Papalote]

I used my Lyman 311041 for the first time recently and found it nearly impossible to get hot enough to cast. I cast(ed) a dozen or so throws. How many times are you filling the mould to get it up to temperature? Pot temperature too low? I am used to the Lee moulds and quick heat up.

1Papalote

[Tom W.]

After you smoke your mold there really isn't a set time frame for it to heat up. A dozen throws is just a beginning. I've had to wait some ungodly long times ( or so it seemed) until I got good bullets. Turning your heat up will help some.

[HeavyMetal]

I put my mold. or molds, on the pot before I turn it on. Preheat times are usually 30 minutes.

This can vary on how much lead is in the pot, if the mold is steel or aluminum and what the current room temperature is!

pre heating is the only way to work a mold.

[docone31]

I stick it in the pot untill the lead falls off. If it is too hot, I go slower untill it is the heat I want.
I had one so hot one time, the lead poured back out!
Learning curve I guess.
Once it is near my favourite casting temperature, I do not use a thermometer, I guage my pouring speed depending on how hard the sprue is to cut off.
One thing I do, I cut the sprue, then leave the plate over the pour hole on the mold for a few seconds before I open it. I believe that prevents a little shrinkage from losing volume in the sprue.
In casting gold, or silver, the sprue really acts as a shrink absorber. With lead, I have not found lengthy time to be a factor in the sprue. Once it is hard, and easy to push, there is very little pull away.
Stick the corner of the mold in the molten lead. When the lead falls off, pour away. At that point, the six bullets rule will apply. Sometimes more. The castings will show.

[454PB]

This is one place where Infrared thermometers are handy. I preheat my steel moulds to 250 degrees before the first pour.

[Marlin Junky]

Go to Wally World and purchase an electric hot plate that outputs about 600 to 750 watts. Place your ferrous molds on the hot plate and turn it on the same time you turn on your casting furnace. With a little fiddling of the thermostat on your hot plate, you should be able to preheat the mold just about the same time your alloy is ready to pour. A 600 watt hot plate set on high is just about perfect for most of my ferrous molds and I usually start casting keepers within a couple minutes.

MJ

[mooman76]

I turn my pot up all the way to help heat the mould faster for steel moulds. Then as it starts to cast good bullets a gradually turn the pot down to where it should be. Also if you are using a top pour I will pour extra lead on top of the mould while it is angled toward the pot to help heat it faster too.

[Shepherd2]

My Lyman pot has a shelf on top to preheat a mould. I put my mould on the shelf and turn the pot full on. It normally takes 20-25 minutes for a full pot of alloy to melt. I usually start casting as soon as it is melted. I expect to get well filled out boolits on the 2nd or 3rd fill. When I feel that the mould is fully heated I will turn the heat down.

[dwtim]

I must be lucky, or maybe it's because I'm casting a DC mould that is 35 caliber. I leave the mould "hooked" on the edge of my pot while it heats up, and it takes maybe four casts before I get a good fill-out. I have a thermometer and temp is maintained between 750-800 once I get going. (This is for an alloy that is close to WW.)

I also found that leaving the blocks open for too long, or placing the them on my steel work surface cools down the mould too quickly, so I don't do these things. When I stop to flux, I hook the mould over the lip of the pot for the duration.

[montana_charlie]

My pot is the old Lyman ten-pound with the bottom spout. The top edge is wide enough to preheat moulds on.
Since my moulds are not as thick (front to back) as they are tall, I stand them on the pot edge with the handles sticking straight up. That gets more mould surface (and the sprue plate) in contact with the hot cast iron, and seems to get heat more evenly distributed througout the blocks while the alloy is melting.
CM

[grouch]

Are you sure you've got all the oil etc out of the mold? It looks to me like that is more likely your problem. Once a mold is clean and broken in, it doesn't take long to heat it up. Maybe 10 bullets or so for my 311041. The first time for any mold is usually a pain in the butt.
Grouch

[1Papalote]

Thanks for the replies. The LYMAN books says don't dip your mould in the pot but LEE says its ok. I have heard stories about warping a mould so I was being cautious. I have always dipped the LEEs so I'll try with the lyman. I tried to heat the mould on the pot rim but maybe didn't get enough heat. I'll use all the advise here and report on the outcome.

Grouch, I was thinking maybe I had oil in the cavities. I will reclean and try again.

Thanks fellas

1Papalote

[montana_charlie]

I have heard stories about warping a mould so I was being cautious.
I'd say you are smart to be cautious, but I don't think that dipping a mould in the alloy will warp it...especially if the mould is pretty hot to start with.

I suspect that warped moulds are caused by those who use a torch to preheat their moulds. Perhaps a propane torch won't do it (I dunno), but some use tools that run on hotter fuels.

In any case, I think slapping fire to a cold mould is asking for trouble.

CM

[hammerhead357]

I am in the use an electric hot plate to preheat moulds crowd but I place mine on top of a plate of 5/8 inch steel. I turn the hot plate on when I turn on the casting pots. I set the temperature to the point that a boolit setting on the plate will not melt and this may not even be relevant. I suppose one could heat them even hotter I just don't. I use what works for me...Wes

[wills]

Also, you can make a "boat" of aluminum foil, put the mold in it and float it in the alloy till the mold heats.