What's wrong with my new Lee 6 cav?

[ccjcc81]

I just bought this, there is flashing around the base of the bullet. The sprue plate looks tight, can't see any light between it and the mold. It did this from the very first fill. The flashing occurs in the same spots every time. I got it up to temp and that didn't help. Is there any way I can fix this without taking this mold apart and sanding it? Rather than risk damaging it more from incompetence, I think I'd take it back to the store, unless there's some quick fix. I tried to tighten the sprew plate screws, but they wouldn't tighten with as much force as I was willing to give them. Any advice is appreciated.

[243winxb]

If using a bottom pour pot, dont pressure cast. Pressure casting is when the spout of the pot and mold are in full contact with each other. Let the alloy drop from above, a slight gap.

[Mica_Hiebert]

lower alloy temp may help too.

[tazman]

From the marks on the top of the mold, it looks like you might have burrs on the bottom of the sprue plate holding the plat off the mold slightly. You can stone the bottom of the sprue plate until the plate is perfectly flat. That may relieve the problem. Also as Mica said, reducing the alloy temp may help a bit. I have used that trick before and it worked.

[ccjcc81]

Ok, I was casting at 750 because that's what my other 6 cavs like, but I'll try again at 700. I'll also look for a burs. Thanks guys.

[Eddie17]

As tazman say's! Those marks on top of you mold indicate a problem on the sprue plate.

[gwpercle]

Smooth out the underside of the sprue plate , I understand your reluctance to take it apart , so do the best you can. Use 600 grade Wet or dry paper backed with something flat , use oil or water with the paper. Smooth out everything you can .
I have a flat Arkansas oil stone that I use, the underside has to dead flat and smooth. Then lightly smooth out the block tops.
Those marks will just get worse , smooth them out now. I've started doing this with new Lee moulds before even attempting to cast with them. Sometimes if you tighten the sprue plate screw too much , the plate will rise up on the other end. Tighten it just enough but not too much....that's not a great description, but follow Lee directions.
Also the holes in the bottom of the cast boolits , photo #1 , looks like opening the mould too soon or not enough sprue puddle. Bases in #2 look good , except for fins.
Adjusting a sprue plate can be a frustrating thing to accomplish .
Gary

[jimofaz]

Your pic shows what looks like too much clearance between the mold & sprue plate. Hold up the mold sideways to a good cool white light. Should be little or no light coming thru. Check the sprue hinge screw & washer for vertical play. Check the sprue plate stop screw for contact with the top of the sprue plate upon closure. Should be snug. If there are any burrs or impact extrusions on the top of the mold, or the bottom of the sprue plate, they will need carefully removed. If all the preceding looks OK, place a straight edge over the length of the bottom side of the sprue plate, hold up to a light, & check for excessive bowing. A new mold should be zero. Lee will replace a bad one under warranty, but you will have to send it back. One last tip ... prolly better not to pressure cast if using a bottom-pour furnace.

[Shuz]

When I address sprue plate flatness and smoothness, I use a piece of plate glass and fine grit sand paper. Lay the sandpaper on the glass and use your fingers in the sprue plate holes to move the sprue plate back and forth over the sandpaper until final result you want is achieved.

[stinjie]

Had the same flashing issue with a couple Lee 6 cav molds.After getting both mold top and sprue plate bottom to a mirror finish,all flashing problems disappeared.Used plate glass and sandpaper from 600 to 2000 then crocus cloth with Mothers mag wheel polish.

[tomme boy]

Sprue plate is too tight and needs to be cleaned and lubed