How to increase the size of sprue puddle

[The Double D]

http://www.fototime.com/9FF4B9DF56ED984/standard.jpg

The mould above is 2.6 round zinc mould. As you can see the sprue is thin and shallow. Too thin and too shallow. So much so that there is insufficient molten metal in the sprue puddle for a draw.

Any body have any idea how to increase teh size of the sprie puddle of this mould.

[Cap'n Morgan]

What's the size of that inlet? 1/2" :lol:

Any chance of placing a short length of 1-1/4" pipe over the sprue - shaped to match the curve of the mold? It will probably leak a bit, and you will have to make a few to keep production going smoothly, but I believe it would work.

[turbo1889]

I think Cap'n Morgan has the right idea. Except for I would take it a step further. Take about an inch length of appropriately sized pipe and cut it in half lengthwise, straight down the center with a hand hacksaw being careful to make a real nice cut. Then true the halves by working them in a swirl motion on top of a nice flat wet-stone like you use to sharpen a knife. Then weld each half to the appropriate halves of the mold, while clamped together in some sort of jig. With a little care I think it could be done and leakage would at worst be a small dribble down the side while the ball solidified. Balls would come out with a short rod extension that would need to be cut off.

[The Double D]

Sprue hole Jan is 1/2", good eye. The sprue bevel diameter is 1 inch.