Sprue Cutter Holes Too Small?

[RogerWatsonfromIdaho]

I was having trouble getting the bullet cavities to fill completely with my Saeco bullet mold, which arrived today. I was using the bottom pour on my RCBS electric furnace, but I also tried my Lyman dipper. I had the temperature set at 850 degrees. I was casting using wheel weights. I noticed the holes in the sprue cutter were smaller than my other Saeco bullet molds. I switched sprue cutters and then I was able to reliably get the bullet cavities filled. The small holes are 0.090” and the holes that worked properly are 0.125”. I thought about drilling out the small holes, but decided that I should first ask. The bullet style is #383.
Has anyone had this problem? What size hole do you prefer in the sprue cutter when casting using wheel weights?

[Calamity Jake]

.125Ø is a good size for that 38 boolet but instead of using a drill use an 82° countersink(the most common, found at any hardware store and is the proper angle for the Saeco spru plate)to enlarge the hole to aprox. .120Ø then on a flat surface use 240-320 grit sandpaper to remove the burr that the countersink will cause on the bottom of spru plate.
You can use the .125Ø drill if you want to but it will make the cutting edge perpendicular to the bottom and make it harder to cut the spru then you will have to use the csk. anyway to sharpen the cutting edge. If you go with the csk use a slow drill motor speed and some kind of oil on the csk to prevent chatter.
If you have access to a drill press, use it, on a low rpm setting and clamp the spru plate down to the table otherwise the csk will grab and pull the plate out of your hands resulting in some kind of injury to the user.

[Char-Gar]

I have drilled out the holes on a number of older SAECO molds. After I run the larger drill through the hole, I place a cone shaped Cratex polishing wheel (on a mandrel) in the drill chuck and bevel and polish the new hole. Works great.

[bobthenailer]

dont open the sprue holes! instead stone a small bevel on the top inside halves of the mould blocks , as recommended in the lbt book, i do this automaticly on every mould i have. take a little at a time until the mould fill out correctly a smaller sprue is desireable.

[Bucks Owin]

I find that if the mowld is hot enough, I don't have any problems with how fast it fills, if that is the reason for bigger holes in the sprue plate. I can trickle the alloy out of my bottom pour almost and still get no wrinkles...

But then I don't mind a little "frost" either..

FWIW,

Dennis

[montana_charlie]

a smaller sprue is desireable.I don't have that book, Bob.
Could you expound a bit on what makes a small sprue hole work better?
CM

[44man]

I pre-drill my holes with a no. 17 drill bit, (.173), then cut the taper in a four jaw chuck until sharp. No problems with any boolit. I have found a large hole in the ladle and sprue cutter works best.

[bobthenailer]

the reason you wanted to open up the hole is for better venting / better mould fill out. by leaving the hole the same size the sprue is smaller/ better, and the improved mould venting is done by the small V channel that you put on the top inside edge of the mould blocks where they meet. take a stone and hold each half of the mould block & stone a small bevel on the top inside edge, try about 10 strokes on each block & cast some bullets, bevel some more until mould fills out well, you can stone the mould when it is hot it will usually take at least 20 strokes on each mould half

[Swagerman]

I had trouble with an older 2- cavity custom 180 grain custom GC LBT mould sprue plate that was too thin and the hole was pretty small.

Finally got fed up with try to bottom pour from my Lee pot and getting not fully formed cast boolits...especially on the gas check area.

My solution was to have a machinest make a new and thicker sprue plate of 1/4 inch thickness and the sprue hole was pretty much the same size but it had a 3/8 inch diameter 1/4 inch conical deep bevel that received the lead pour and filled the mould right up to the sprue plate.

If you've ever seen a Hoch custom made mould its that arraingment.

Jim

[Willbird]

I'm not sure what your casting alloy is, but straight WW can get like soft serve ice cream kind of, the solution is to raise temp, or add a tiny (like 1%) amount of tin. Makes the silver stream pour nicer.


Bill