Correct Casting Temp. for 92-6-2 Alloy..???

[sargeny1]

Hi All...This question is tied into a post from me yesterday...my Lyman and Rcbs thermometers always read way under 200deg. when cold....I used a small pot of boiling water to test them...I am at sea level and water boils at 212 deg at sea level...they both registered a little under the start temp. of 200 deg.... I figure they are at least 25 to 50 deg under that 212 deg. boil point of water....

OK...what temp should I cast using 92 lead - 6 antimony - 2 tin Alloy..??? I am casting for 357 41 and 44 magnums using Hensley & Gibbs KEITH molds....#51 #258 and #503....keeping in mind that my thermometers register at least 25 to 50 deg. less than what they indicate.....

What say ye learned gentlemen..???:?:

Thanks to all.....

[Defcon-One]

My RCBS thermometer reads at least 40 deg. lower than true temp as well.....

It bothers me because it cost me twice what a generic one would have and the others that I have seen, all generic, were more accurate and much closer to true temp.

Casting Temp really comes down to, "what works for you?". I cast at around 700 degrees F. If I do not get good fill out, I bump up to 750. Once the mold is heated, then I back down a little when/if they start to frost. These are actual temps, you would need to adjust that to your thermometer and its error.

[sargenv]

I usually cast in the range of 725-750. I put two "corn cobs" on the pot as replenishing supply.. When I cast about 60 bullets (whatever 2 pounds of alloy is) I drop the pre-heated cobs into the pot, and the temp drops to about 675.. still within casting temp.. and it usually will get back to 725-750 by the time it's time for two more pre-heated cobs.. I do this with 92-6-2, ww's, or even the range lead I use as cores.. I find that if I go too much higher, the molds overheat quickly and the pours get erratic.. I use a bottom pour Lee 4-20 with a casting thermometer.

[mold maker]

Most all thermometers that are for hobby use (that's us) can be depended on to be somewhat less than accurate. Precision ind. thermometers cost way more than what most of us are willing to spend.
Ours are probably much more accurate at casting temps than at the starting end of the scale.
It's kinda like the dial on our pots that read from 1 to 10. There is no exact relationship to F/C. temps. It's just a reference scale.
I have 2 brand name casting thermometers, both too expensive for the accuracy they give. They don't agree, and I use them just like the dial on the pot, as a reference only.
Experience will be as good a judge of correct temps as cheap (quality) themometers.

[onesonek]

Well,,in a sense it really don't matter what it reads or is off abit. Naturally it would be nice if it was correct for what they cost however. But what I would do in this case, as suggested by Gearnasher, is to bring the alloy up to full liquidous then cast at a 100 degrees beyond that. That rough will put you between 650 and 700 with most alloys as I understand it.
This was just discussed also in the Cast Boolit forum a day or so back. Gear explains it so much better,,,here's the thread link

http://castboolits.gunloads.com/showthread.php?t=120902

[John Boy]

OK...what temp should I cast using 92 lead - 6 antimony - 2 tin Alloy..???
sargeny, I hate to tell, there is no specific temperature to cast a specific alloy!
It all depends on the mold temperature that frosts the sprue puddle in 5 -8 seconds for nominal bullet weights under 300gr and 8 - 10 seconds for nominal bullet weights greater than 300gr. For any bullet, insure you do a 5 second pour with a heavy head pressure created by the spout of the ladle affixed tightly in the sprue hole
These factors will produce non frosted bullets and ones that completely filled out in the mold. Plus if you maintain a steady casting rhythm, the weight variance will be within 0.5gr if you do it correctly

[lwknight]

You should be able to expect good results at around 650-675. This of course after your molds are up to production temperatures. I have never had a need for temperatures over 675 degrees.

[rbertalotto]

Build a PID to maintain perfect casting temperatures and you can put your casting thermometers in the drawer.

Article here:

http://rvbprecision.com/

[zomby woof]

650




..

[btroj]

Can't say, don't own a thermometer. I just get the stuff melted and then cast. I try to get the melt hot enough to cast well, no more.
My moulds don't seem to be able to tell the difference between 625 and 650 so why should I care?