Bifilm Pouring Basin

What's the height of the puddle on top?

 

You mean the spill? Mine are usually around 3/8" or a little thicker. I'll measure that one.

 

Just curious whether it's 0.486" as calculated. A lower value would indicate a contact angle of less than 180 deg. This angle should differ from your green sand to mine.

 

I'll try to estimate the contact angle. It grows in areas where the puddle is fed after the surface starts to firm up, of course. I think 180 degree contact angle is theoretical, but aluminum does get close.

 

Got started on a centrifugal separator today. From watching ESC's video I'm sure it will have enough flow rate to work. Basically a wide bottom blind riser (or open riser). I plan to have the separator and runner in the cope.



The disc below will be bound sand, in the drag.

The internal is light wood, bound sand, part of the disc, with an exit hole in the middle to let metal out the bottom.



I kept the the annular space between the cone and the riser, inside the riser, the same as the runner to keep the velocity up. Might not be a good idea after seeing ESC's velocities, but the metal can flow up as well.

The gate coming out the bottom will be in the drag the thickness of the disc with an offset parting line to feed the pattern lower than the parting line. (set up for picture upside down)



Another view of the gate



I'm interested in comments. I think this will both separate entrained air above, maybe bifilms, and heavier materials like sand grains below. Open riser above and flow path out below should really slow the flow down. I hope. And still have an inlet riser to feed shrinkage.

 

I measured an iron blob I accidentally spilled a while back and it was very close to .375.” Fwiw.

Here is a slight variation on a theme of pouring basins. One basin, several sprues that can be fitted into it. I started to make several basins with sprues glued in place. Then, being lazy, decided this might save a little work. I put the sprue opening off center partly because it might make using my “mousetrap” plug mechanism easier. The taper is not a precisely calculated angle as I have feeling that angle is not super critical. I have calculated pour times of around 10 seconds for my 40 pound casting. And I must say the runner and gates look ridiculously small. But, I’ll give it a try not planning on perfect success out of the box.
http://forums.thehomefoundry.org/in...cate-and-plug-lift-mechanism-fabrication.657/

I am hoping the mousetrap will allow me to pretty well fill the basin before metal starts down the sprue I think there is a 95% chance of getting a test pour done within the next three days. Finally!!! I will do my best to get a video of the whole fiasco.

Denis

 

Looking good! I'm starting to like the wide pouring basing, with a wider weir there is more metal coming into the small well with just a little overflow. I consistently can't pour hard enough to keep the sprue filled. I'm heading toward smaller sprues. Did you see ESC's glass flask?

At 40 lbs that's what, over two quarts of metal? That's a good sized pour.

 

Yes, I saw esc’s glass pour and put a like on it. Extremely interesting. I am sure many/most of my pours to date have involved poorly choked sprues. That is where I HOPE the smaller sprue and runners plus the mousetrap should help To be honest, lurking in my heart is a worry about incomplete filling due to small runners. But that is based on only prior experience, and thus familiarity, with large sprues and runners. Just gotta try it and find out.

Denis

 

The filled sprue is of value to avoid bifilm defects. I believe if you dribble your metal into a sprue you will get a slow even fill of the mold with little turbulence. I think that is ideal for filling the mold, is it not? I've heard hot and fast and I've heard gate for slow filling. And I've heard more about tutu's in this forum than I ever expected.

 

The dribbling would allow a non-turbulent meniscus to rise in the mold. The down side would seem to be that the blobs that compose the dribbling stream are pulling in air and forming complex oxide film folding and refolding. I am aiming for low pour height, full basin at least most of the time, orderly fill of my mold, and good luck! Neither of my patterns lend themselves to easy bottom-up filling So that’s not happening. It will be side filling on the one. Sort of bottom up and over the top on the other. Compromises, compromises, compromises.

 

I made an offer on this auction of $30 the Seller was adamant for $50..... plus the $20 shipping. This guy thinks anything that's old is worth $$$$.

 

Yah, that "easily" word seems to keep cropping up ;-)

Denis

 

Got a glass flask put together today. ), 0.2"x0.2" runner. I'm interested in seeing if it will stay full, if it doesn't cool off and stall.



This is the glass out of a quartz light.



Runner feeds up into the riser, then gate comes out the bottom but no straight shot through.



No vents, but this is green sand. However one side, the glass, has no porosity unless it cracks.

I'm considering preheating the glass immediately prior to pouring. Hmmm.

 

And can you put some sort of pad under the C-clamps where they bear on the glass. Maybe kevlar, silicone rubber, or even wood. By the time wood pads would char or silicone would have enough heat transmitted through the glass, the pour would be over and frozen. Steel on glass puts a lot of point pressures on the glass I should think.

Even wafers of IFB might make crushable spacers to place between clamp an glass.

Denis

 

I do have strips of wood under the clamps. I'm planning to loosen the clamps slightly just before pouring to let the glass grow if it will rather than crack.

I'm assuming the sand will absorb pressure from sand expansion.

 

Yup, I see that now in one of the photos. It is there in others, but glass clarity makes it hard to tell what is above or below the glass. Sorry.

Denis

 

Unlike me, but I did clean the glass a little before trying to take a picture through it.