what temp do you run your hotplate to preheat a mold and for how long

what temp do you run your hotplate to preheat a mold and for how long do you wait before using that mold
Thanks

Just hot enough that a few casts will finish bringing the mold to operating temperature. Depends on mold, alloy, casting style... 350F might be a place to start.

I have a Wallgreen's hotplate with a 3/16 slab of steel across the coils and a peanut can with a hole in the side for the mold covers the whole burner. I keep it midway between Med and High but they are cheap controls and every one will be different.

smoke,

I set my hotplate on medium. I plug both the Lee ten pounder and it at the same time with the mould on it. When the leads ready, so is the mould.


Cat

My old "coil type" hot plate has Low, Med, and High. Then there is 3 dashes inbetween each.
I run mine one dash above Low.
I've never connected a thermometer.
If I run it at Med. the mold gets too hot...too hot meaning, when I start casting, the sprue doesn't freeze for 20 or 30 seconds.
trial and error Baby !
Good Luck,
Jon

I am simple and don't use a thermometer. Never had one when I was younger and don't feel the need now so I can't give exact temperatures but what I do is pre-heat until the sprue plate lube starts to smoke a bit. That puts the mould a little hot to begin with but it also gets me good boolits almost right away and as I cast the mould temperature drops a bit and I set my casting cadence to suit sprue puddle freeze time. Once rolling I have a few seconds after pouring to wait for the sprue puddle to freeze.

That's what works for me anyway.

Longbow

I use a 300 degree Tempilstick on the mold block itself. This takes a medium setting on my electric hotplate and about 2-3 pours then to get good bullets from a 6-cavity aluminum block or 4-cavity iron one.

will that clears up another issue for me .. I had my hotplate too hot..

thanks for the replys

I have no idea how accurate it is but my flat hotplate has a 'thermostat' that goes to 300. I put it at 300 and leave the mold on it until the melt is up to temp.

I just bought my first hot plate a coiless oyster at wallmart. I converted a 3 guart sauce pan into the "oven" for it/ I have 3 slots for mould handles to set thru. I may drill a hole for a thermometer yet. I was wondering how hot and how long this post answered that for me Thanks guys.

I use the little furnace made from an electrical box. I have a BBQ thermometer in the top (cheap) and set to reach and hold 500*. I turn the pot and hot plate on and let it all heat soak while I work on other stuff.
My first boolits are perfect with lead at 750*. I can dump a 20# pot with zero rejects using a ladle.
Have to watch some hot plates, they are not made to get real hot because liquids in a pot suck the heat away. The thermal fuse in the bottom can blow so I bypass it.
If the hot plate quits, take the bottom off and find the fuse, solder a heavy copper wire across it. It will be inside a shrink tube.
You are bypassing the safety so keep an eye on it. I have had no problems.

Medium for me and I put an old saw circular saw blade on the coils to help spread heat and protect lee mold. Sometimes I turn it up higher if it seems to need it. Depends on mold. When I put new ingots in 20 pound pot I put mold back on hot plate.

I took my thermometer and set it under the edge of a brass mold on the hot plate and adjusted the temp setting on the hot plate until it reached 500 deg. The dial was just a little past MED. I took my white paint marker and marked the spot on the dial. I turn on the pot, add the ingots and turn on the hot plate, and when the pot is ready (750 deg) the mold is ready to go and I get perfect boolits from the get go. This way saves me time and energy by not having to remelt the first few casts.

I have the cheap Aroma brand hot plate with the flat surface. I put my Mihec 4 cavity brass molds on it at the same time I turn my RCBS Pro-melt on. I have started with medium, and have tried increasing the temp to the high setting, but the mold was getting too hot, and the sprue took a long time to cool. My last session I ran the hot plate with the indicator point to the last "M" in Medium, and that seemed to work pretty good. According to the Lyman thermometer in my melt the casting temp was at 760°, which I think was a bit on the high side, as I had a bunch of frosting on air cooled boolits, but not as bad with same boolits that were water quenched.

Coiled hot plate topped with aluminium cookie sheet from toaster oven. Cranked up all the way hits 400, which is what works best here for 2 cavity Mihec brass mold.

I find that setting my HP to '4' works best - '5' gets the moulds too hot, and the sprue floods off like water.

Don't use it for that any more, just put the mold on the lead and let it heat up while i'm gettin ready to flux & stuff.

I "think" some Lyman moulds have a lead pellet between the set screw and sprue pivot screw as a means to keep the pivot screw from turning. If you get the hot plate too hot or get the mould too hot, that pellet may melt. I think that because my pivot screw began self loosening and tightening as the sprue plate was cycled. Tightening the set screw had no effect, so I removed it to find lead set-up under the screw preventing further tightening. How else could lead get in there. I used propane to liquefy the lead and a nub of #10 copper wire to replace the "assumed" lead pellet. I also flattened the side of the sprue pivot screw were the copper was pinching it, that way it can not turn.

prs

I have an Elite burner rated at 1000w and will set it on Medium with the mould on top while the lead is melting. Once the lead melts and the thermometer indicated about 650 or so degrees I'll check the mould temp with a Neiko Laser Thermometer and aim it at the mould. If it's close to lead temp I take it off and start casting.