Metal Casting Zone

xlchainsaw wrote:
nice project . put your sprue in the middle and use your legs as vents....should come out ok. the only problem is that you will have a sprue mark to polish out. oops i noted that you are molding in the cope???? i would put it in the drag as you are using metal rising to fill your mold. metal doesnt rise very good unless you have have some pressure behind it..... you could make a bigger and longer sprue ...it might help.

ok think of you sand as a filter bed, the gas has to flow thru it to escape. useing a pointed nail (10 d) you will push it down till it hits the pattern and remove it about every 1" this will help to vent the mold without leaving that darn shrink crater a vent will make. You probably wont see the the holes you have made on inside of the sand mold but trust me it is there and working due to the gas not having to escape thru such a thick filter bed. I have to go to bed now whife is yelling at me LOL

Hey Aonemarine,
Thanks for all the help and explanations. Best not to get the better half too mad.

Try larger runners and two ingates on the long side. A rule of thumb for sprues and runners is a 1:4:4 ratio between sprue, runner and ingate. The sprue can actually be fairly small, try and reverse the sprue and runner size. The smaller sprue will allow you to keep the system full and will cause less turbulence and air bubbles. Otherwise it looks as if you did everything okay, I would probably do it the same way, with the addition of larger runners and a few more gates. I would also poke a few holes in the middle with a vent wire (just a stiff length of wire to poke small vents with) to make sure the air isn't getting trapped in that middle bubble. You can always snap off the small vents and finish it later.

Pendragon56 wrote:
Hi Xlchainsaw,
I thought about doing that but won't I have sand erosion and such without a basin at the bottom of the sprue? I'm ready to try anything to make it a repeatable pour. You guys have been great. It may take me a couple of days to try all the suggestions.

Thanksyes and no about the erosion. you are using petrobond???? or similar??? ive done plenty of "boxes" .... sometimes i get a "gritty" ring on the inside where the sprue is and sometimes just perfect. i use sand and clay and dont know about petrobond. i put it down to my sand may be a bit too wet at times.try odd ducks method first and "prick" the mold as a 1 suggested. a finer finish would be achieved by molding in the cope however "gas " gets trapped very easily.

Putting a sprue on either side will also help by shortening up the runner length and keeping the metal hotter as it enters the mold. the way you have it now the molten metal is traveling quite a distance across the mold to enter the patern. Dont worry youll get it worked out for repeatable perfect castings.

Hi pendragon 56

Good casting ,,you are so so close with this . Thanks for the pics just as I expected from your explanation.. Hmmmmm. Bigger runners and a tilt on the mould to one corner will help .As this mould is poured the metal runs around the sides and fills them all evenly to the same level, metal runs throught the cavity to cast the thin base and can't push the air out quickly enough vents or no vents. If the mould is on a tilt to one corner the base will cast,or fill from one corner up to the high corner being vented at the highest leg. Still a pretty good result 56 Try again Keep us posted