Bottom pour techniques

[Conditor22]

650 is low even for hard alloy shoot for 720° next time out.

Even new furnaces need to be cleaned before using

this is crude but it works for spout cleaning

[Walks]

Never had much success with pressure casting.

I adjust my mold guide so that there is about 1/2" of clearance between sprue plate and spout. That way it will clear the sprue, barely. I preheat my molds on a hot plate, at a #4 setting, checked it once, seemed to be 400-450degrees. Turn the mold on it's side so both mold and sprue plate contact the hot plate.
I always use molds of the same height, that way I get a smooth rhythm. Three Lyman 2 cav or a Lyman 4cav and RCBS 2cav.
Regardless of where my Alloy comes from, I always flux every time. Even if I made up the alloy myself and fluxed it twice before. I also flux whenever I add to the pot.

And I lube with Synthetic 2stoke after the 3rd fill.

[Mike W1]

Might as well add my 2¢. You'll find as many solutions as there are reply and they'll all work. Some of what I find to be the variables are the type moulds both size and mould material. The weather temperature you're casting in, etc. I'm no expert compared to some of these guys but my methods work well for ME at least.

The biggest things I've observed over the years that you (make that I) need is a smooth steady flow of alloy into the mould and I don't want the stream hitting the sprue plate at all, but directly into the sprue hole. It takes a "feel" after awhile and I know before I open the sprue plate if I'm gonna have a "bum" base.

Now my wife says I love toys and she's right. And the ones I use make it easier to control my results. I use stacked Lee 10# pots. Why? Because that's what I started with and I'm used to them. There's better ones out there but really it's just pouriing hot lead into a mould when you get down to it.

The only way I've found to get an easier to control smooth flow that "feels" consistent is I don't put as much metal into my pouring pot. As a guess I'd say I only empty to maybe 2 lbs of alloy and don't fill it to more than 6-7 lbs capacity. Makes that "feel" easier to maintain. Having that feeder pot PID controlled insures my casting pot temperature is not going to change. It probably adds a couple minutes to the equation but little breaks are always welcome.

I only cast pistol bullets anymore and an alloy of about 1% Sn with 3-4% Sb fits my needs just fine. I cast indoors in shirt sleeves year round so weather is not a problem. I only (normally) cast with Lyman DC iron moulds and they seem to like 310-320° so that's what I strive for. I never had much luck with Lee's until I wised up and bought a hot plate and preheated things. Everything I use including that hot plate are PID controlled. A bit of experimenting and I found 440° to be the sweet spot to maintain that 310-320° in the moulds. When I turn the pots on along with the hot plate and the pots are at my set temp of 365C (689F) I'm confident the first bullets out will be good and I've weighed a LOT of them. If the sprues start to feel like they are cutting a little too easily I just set them for a bit on the shelf that has a fan blowing on them. Another "feel" thing that comes with doing any chore for that matter.

Have also experimented with homemade aluminum sprue plates with some success but need to dig a little deeper on that this winter. At this point my thinking runs toward my cooling fan/shelf is probably just as effective. One thing I am sold on is removing the sprue plate stop pin and drilling/tapping for a socket head set screw in it's place. It really cut down on the different weight range between the 2 cavities. Should be a picture on here somewhere and I'll post that.

It seems to be a learning process each time out and I feel like I learned a lot from those PID and TC's. Hope some of this drivel is of use to you.

[Mk42gunner]

Mostly you need: hot enough, air gap, nice puddle. But I do have a couple molds that think they've gotta' have contact. Whatever it takes.

I agree completely. When it is time to cast with a mold that demands pressure filling it is a real PITA remembering just how to do it.

My one mold that demands pressure filling is a single cavity Ideal 313445 that I was on the verge of sending down the road, until I got my first I Frame S&W in .32 S&W Long. That little revolver just loves those boolits. I'll cast up a pint or so of them which is really quite a few and then forget about it for a few years.

Robert