First casting session, need some advice!

[zipdog]

I just completed my very first casting session, and I have a question. The first few drops produced relatively shiny boolits, but then they started appearing frosty, with the front band cracked/chipped on some. My melt temperature was 670-680F. The alloy was 10.25 # ww + 2.5 oz Sn - should be about 2% Sn, assuming 0.5% Sn in the WWs. Mold is a Lyman 410459, and I preheated it by allowing the mold to rest on the top lip of the pot while waiting for the ingots to melt. I was using a Lee 4-20 with the sprue plate approx. 1/4" below the spout. I was counting to 6 before cutting the sprue and dropping. I'll try to post a pic later. Thanks.

Rusty

[VTDW]

Sounds as though something got too hot. Probably the mold. I decided I like shiny boolits so I slowed down my casting and allow the mold to cool a bit more. I watch the dropped boolits and when they begin to lose their shiny appreance a bit I light up a cig.

[44man]

Mold too hot, casting too fast. Slow down, relax. Counting to 6 is too fast before cutting.
My friends all have trouble, one goes like mad and gets rejects and another will go so slow puttering around he gets all rejects. You have to develop a pace, not too fast and not too slow.

[zipdog]

Thanks, guys. I wondered if that might be the problem, since it started after the first few drops. I was trying to go as fast as possible....need to enjoy the process rather than trying to get to the end.

Rusty

[mstarling]

The analyses so far are right on.

The trick is to find the right alloy tempreature and establish a cadence that keeps the mould at the right temperature and gives good bullets every time. Patience and experience is the key.

Especially with larger bullets, I find that running two moulds in rotation is a good idea. Helps keep the cadence at a reasonable pace and makes me feel that I am being productive.

[zipdog]

Is this a great site, or what...

[floodgate]

zipdog:

You're well on your way! Frosty boolits indicate the high end of the casting heat range - IF fully filled out (frosty and shrunk suggests too cool + contamination; another problem altogether) - and are OK if you don't mind the look - many of us like them frosty.

But, if you cast in that range, wait a tad longer for the sprue to cool and "set"; frosty and breaking off corners indicates you are opening the mould before the boolit has completely "gelled".

But, as I said, you're well on your way, and are making the right moves - observing, thinking, and checking how the casting process proceeds.

floodgate

[zipdog]

I had a thermometer in my pot and regulated the temp to 670-680F. I wouldn't have thought that was on the high end.

[grumpy one]

Depends how hot your mould is. Last session I experimented with how low I could push the pot temperature with a hot mould. Using a single cavity Lee and my 1.3% tin, 6% antimony alloy (liquidus temp is 520*F) I found I could just barely pour good frosty bullets at 550*F, and could do so with temperature to spare at 575*F. The secret is getting the mould hot - at 575*F I was touching the mould onto a wet rag after each pour to cool it quicker, whereas at 550*F I didn't need to do that. Cycle time was just slightly faster at 575*F because I could judge the amount of time in contact with the rag so as to get quick and consistent sprue solidification.

[454PB]

You will develop your own method with practice. All the previous replies are right on. I'm one who likes lightly frosty boolits, and I cast WW alloy at about 720 degrees, then use either two moulds or a damp sponge to control mould temperature.

[NVcurmudgeon]

zipdog, all the above replies sound correct. One other thing to watch is that there can be a lot of variation in thermometers. It doesn't matter too much because you are only usng ONE thermometer. Get the rhythm of castng to where you are making good boolits then it will be easy to use your thermometer to return to the magic temperature for YOUR operation. Also, different moulds have individual temperature preferences. (Aluminum vs. steel, size of blocks vs. size of cavities, etc.)