Breaking in a new mould

[jpuke]

I got myself a new Lyman mould the other day and today I finally got to try it out.  I spent a few hours and cast around 150 bullets of which about 6 were acceptable - and I'm not that picky.  I made sure the alloy was hot, the mould was hot and degreased but I kept getting wrinkles.  The other problem that I had was that one half of the mould would produce clean bands while the other would produce half-filled, frosted ones.  I made sure to watch which half but both would do it alternatively.  Do I just have to be patient and keep casting or is there something else I can do to speed up the break-in process.  I'm fairly new to casting and all previous experience has been with aluminum moulds.  Any advice would be appreciated.  Thanks.

[sjc1]

I like to run my lead temperature at 800 degrees. I keep a thermometer in my lead pot so I know what the temperature is at all times. It sounds like your mix is hot enough if you are getting a frosted bullet.
Make sure your sprue plate swings freely. It should swing aside by it's own weight. You do not want it too tight.
Make sure your sprue plate is completely flat. Lay it on a piece of glass to see if it is indeed flat. If it is not, get in touch with Lyman and they should send you another one. While you have it off, and on the glass, put a piece of crocus cloth face up on the glass and smooth out the bottom side of the sprue plate. This will remove any burrs on the underside of the plate. Check to make sure the holes in the sprue plate are of the same size. I have had similar problems with molds and after making sure the sprue plate was flat, was swinging freely, and smoothing out the bottom of the plate, I have solved the problem by enlarging the holes in the sprue plate. Some molds need this and others do not. Each mold has it's own mind.

[hubbard]

i've never had a new mould, steel or aluminum,  that didn't suck the first time out. wrinkled bullets,round edges,etc.. but time seemed to cure these problems. at the second casting session or at worst, the third, everything worked out. so don't give up. try again tomorrow.   good luck.

[jpuke]

Thanks for all the advice, the sprue plate was a bit tight and I'll be patient and see what happens in my next casting sessions.

[Billy Marr]

I have found that degreassing is the most important thing when working a new mould. I use brake cleaner and a tooth brush followed by hot soapy water. Then cast.

[sundogg1911]

I almost gave up casting bullets after my first time. I had 3 new (brand spankin' new) moulds, and I spend the whole day making "bad" bullets.
After doing a little reading and research about casting. I learned a few important things.
1) 1 pound of 50/50 bar solder to 9 pounds of wheel weights really helps fill out the bullets
2) degreasing a new mould is a must
3) consistant temperture (I usually cast at 800F) makes a big difference
4) ask a lot of questions. No one (that I know of) know's it all but a lot of people know a lot and are glad to share their information with other people that share a common interest

[sundog]

Sounds to me that IF your mould is clean, and IF your alloy is HOT, you have one of two problems, or both.  First, venting.  Loosen that sprue plate.  You can also chamfer the mating block edges on a stone - just a little - to make a new vent line through the tops of the cavities under the plate.  All of my moulds get this treatment.  Second, add tin to the alloy for a better fill out, but I tend to think your mix needs to be hotter first.  Third, yea, I know, I can't count...,  Third, lightly smoke the cavities with a wood stick match or butane lighter, or swab the cavities with a qtip with mould prep.  Oh, one more thing.  Sprue holes are usually not large enough to allow a good flow.  Open it up a LITTLE from the top only, but be sure to hone the bottom side of the sprue plate to remove burrs.  sundog