Accessory Pouring Basin

I guess I am having trouble visualizing what you mean by lips. Could you do a napkin sketch?

sorry to be so dense.

Denis

 

A negative draft that partially encloses the basin? I'm listening

 

In the nautical area I live in we call that tumblhome when referring to hull design. That’s my guess but I want to be sure that’s what Billy is saying.

Denis

 

That's exactly the profile I had in mind Dennis which would be interesting even if I'm on the wrong track. Best wait for Billy.

 

Sorry guys...was away from the computer.

 

Another view. We pour really fast so having a pour cup that eliminates splash is essential. It would require negative draft on horizontal mold but is achievable with many different processes. It is not the only design we use but this one is the most prevalent. Using mechanical patterns is much easier than you would think in sand molding and you can do lots of negative draft molding once you determine that it is worth the extra effort and cost in building the tooling.

 

I designed some smaller cups for the lighter molds that probably illustrate it better. We use these cups on the jobs that have depressurized systems and are light pour weights. The biggest issue we have when using these is the relatively small cup doesnt give you a lot of wiggle room for pouring so you need to be accurate and able to stop instantly.

 

Without seeing it with the sprue and gate I'm not getting it (but I am the village idiot)

Edit: The last image seems to make more sense but still intrigued.

 

These are vertically parted molds. The two flat side are the top of the mold and where it mounts to the plate. This is a pic of one with sprue attached at the bottom.

 

I am gathering that you are making something of an hourglass-shaped pouring basin with a broad opening, a narrower waist, and a broad base. In a vertically parting mold the each half of the basin could have draft so that when you look down from above the sides of the basin perpendicular to the part line actually intersect at the middle of the cup with a 176 degree included angle if the draft angle is 2 degrees.

Making the equivalent in a horizontal parting mold would be challenging. Possible with loose pieces I guess. But challenging. But hand carving one could get most of the benefit, it would seem, by simply widening the base of the cup somewhat greater than the top opening. And you probably Could get even get more splash reduction by undercutting the lower bottom of the cup by maybe 10% of the cup width.

For me, pouring with a really full crucible makes fine control of the first few pounds tricky. Square junctions of the sides to bottom of the basin helps. But, undercutting would be easy. I can visualize metal hitting the bottom of the cup and shooting off toward the side but being rolled back toward the center rather than up the side by that roundish undercut. I will definitely do that next time.

Thanks for the pointer, Billy.

Denis

 

It's possible to make a separate pouring cup in sodium silicate or preferably resin sand and just sit it on top of the sand mould, we do that for bronze all the time so it should work for green sand just sitting on top. If it was all resin sand, some Dow Corning 732 silicone can glue it in place for the pour.

 

Not only should it work, it does work to place a separate green sand mold pouring basin on top of the green sand main mold. That is what started this thread, If you take a look at the second video in the first post of this thread, you can see the accessory basin I used. It worked well as a basin, but the general gating pattern was not ideal for this casting.

Denis

 

I'll try to pay more attention in future ...time for bed.

 

No worries, Mark. But it is MORNING here!

Your post caused me to go back and view the pouring video in post 1. It demonstrates quite nicely the wallowing around and slopping of the beginnings of the pour. That basin was not cut with sharp square corners as it was about then that I started thinking about strategies to reduce wallowing. The video makes a good case for undercutting. Subsequent pours with sharp intersections of base to sides side to sides has reduced wallowing. Undercutting should work even better.

Denis