Ball Hopper Monitor - Casting Project

[GreenTwin]

Well, before you try the moonlight requisition.....

The next time she goes to the store ask her to get a box of cornstarch. Tell her you need some for an experiment, which ain't a fib. Tell her she can have the new stuff and you'll take the old stuff, also not a fib. Happy wife => happy life.

My wife was all good with the foundry stuff until the flames started in the backyard.
She has been suspicious ever since.
.

 

[Fidlstyks]

I use wood flour in my cores. With Linseed oil, funny the more water I use, the harder the baked core

 

[Fidlstyks]

I stop at the Amish Cattail Foundry in Lancaster Co Pa.
They use a coupola with short sprues and no vents. I vent every thing. I use the vents for cast iron welding rods
I like taller sprues, they fill molds better.
The book I have says to make the iron swirl going down the sprue hole.

 

[GreenTwin]

I use a short sprue typically, but I use vents at the high points of the mold.
With greensand, I have seen some get away with no vents, due to the permeability of the sand.
Not a good idea with bound sand to leave out the vents, as I have found.

The sprue on the water hopper is going to be taller than I like, but there is nothing I can do about that.
A tall sprue increases the velocity, but that is probably a necessary evil in some cases in order to fill the mold completely.
There are tradeoffs in casting work.

The swirl would seem to be bad, since that would suggest turbulence, but I think any fluid poured down a sprue is going to swirl, regardless.
.

 

[GreenTwin]

I asked my wife if we happened to have any corn starch.
Her completely predictable response was "Why do you need corn starch?", as if that were really relevant to the grander scheme of backyard casting endeavors.
Translated, that means "are you getting into my kitchen stuff again for that foundry stuff you are doing in the back yard with the big flame ?".
I said "Its to reduce the strength of the filler".
I am not sure she understood my explanation, but she did give up the corn starch without further interrogation.

So now we try some corn starch/Fastpatch experiments.
.

 

[GreenTwin]

"Operation cornstarch" test is underway.
I mixed it 50/50, which is probably an excessive amount, but ok for testing purposes.
Hopefully nobody will notice the missing measuring cup until the experiment is complete.
.

 

[ddmckee54]

Yeah, for some reason most wives don't really see the need for having your own personal backyard flame-thrower. Go figure.

At a 50/50 mix it might be really soft and crumbly when dry.

 

[Fidlstyks]

Are you going to use cast iron or aluminum,?
We discussed alumimum and velocity before, in aluminum, I ment more at hydrostatic type of pressure, pouring rate with aluminum is said to pickup hydrogen. I need to study that.
I think castiron likes it. But iron burps the air, I even like my vent lower at times. I think it creates hardspots when on a tip, and velocity helps fill molds.
I think velocity helps with brass too.
My castiron pours like water.

 

[GreenTwin]

I have a heater blowing on the test piece.
It smells like something is cooking.
If the wife asks about the smell, I will have to come up with some sort of evasive answer.

I will mix up a 70/20 mix and see what that does.
.

 

[Fidlstyks]

"Operation cornstarch" test is underway.
I mixed it 50/50, which is probably an excessive amount, but ok for testing purposes.
Hopefully nobody will notice the missing measuring cup until the experiment is complete.
.

What are you mixing with corn starch, half would be too much for anything. I have a formula from a CW Amen book for cores. I can look for it. But the wood flour works better.

 

[GreenTwin]

Are you going to use cast iron or aluminum,?
We discussed alumimum and velocity before, in aluminum, I ment more at hydrostatic type of pressure, pouring rate with aluminum is said to pickup hydrogen. I need to study that.
I think castiron likes it. But iron burps the air, I even like my vent lower at times. I think it creates hardspots when on a tip, and velocity helps fill molds.
I think velocity helps with brass too.
My castiron pours like water.

My permanent pattern halves for the water hopper will be castin in 356 aluminum, and one way to solve fill problems is to increase the pour temperature a bit, to allow a longer fill time without solidification.
The tradeoff of elevating the pour temperature much above 1,350 F is that the surface finish can become more rough, and also the longer the melt is heated after reaching 1,350 F, the more hydrogen it absorbs.

One the permantent pattern halves have been cast, then I will use those to make a full mold, and cast that in gray iron.

I can superheat aluminum very easily, but I don't really know what is happening temperature-wise if I continue to heat iron for over an hour.
I don't have a good way to measure iron temperature, but from what others have said, an oil-fired furnace has a typical iron pour temperature in the 2,400-2,500 F range.

I have noticed that if iron is heated beyond what is required for a complete melt, it does begin to emit sparks out the lid opening, and I interpret this as a sign that the melt has increased significantly in temperature above 2,400 F.

The ferrosilicon helps make the iron more fluid.
Too much ferro causes excessive shrinkage and hot tears.

If a iron scrap that contains phosphorus is used, such as old radiators, the fluidity goes up a lot, but supposedly at the expense of having a metal that is not as strong as Class 30 or 40 gray iron.

The art-iron folks who use a cupola seem to get some really hot and fluid iron, and so that iron may be above 2,500 F.

Are you using an oil-fired furnace, cupola, or induction furnace?
.

 

[Fidlstyks]

On Amazon, one supplier sells a quart, one a gallon for the same price.
For baked sand cores with linseed oil and water

 

[GreenTwin]

On Amazon, one supplier sells a quart, one a gallon for the same price.
For baked sand cores with linseed oil and water

That is an interesting product.
For a core, I think that would work well.
For a filler, I think it needs to be something like corn starch, or anything as fine as corn starch, else it may cause a rough surface finish.
.

 

[GreenTwin]

Test #1 is complete, with the 50/50 mix.
The filler is easily sanded, and the ridges can be sanded down flush in just seconds.
This is much more like spackling compound.
A little too soft though, since you can brush it off with a dry paper towel.

Test #2 is underway.
20% corn starch, 80% Fastpatch.
I put an area of 100% fastpatch adjacent to the 20/80 area, so I can sand on both, to compare.

This is going to be a huge time saver if this works.
The hardness of this filler is not critical since it will be coated with shellac, and also this is a temporary pattern used to make a permanent aluminum pattern, and so any finishing time spent on the temporary patterns needs to be minimized.
.

 

[GreenTwin]

When a filler is too hard, then a significant amount of force has to be applied in order to sand it.
Inevitably the force applied cannot be applied perfectly evenly, and so you end up gouging the filler and sometimes the pattern, and you don't get a smooth surface.

With a filler that is not too hard, you can skim over the surface and knock off the high spots, and get a very smooth even surface very quickly.
A less hard filler is also easier on the hands and wrist, especially if you do a lot of sanding.

.

 

[GreenTwin]

The 20/80 filler test is complete, and the results are pretty good.
I sanded the 100% fastpatch beside the 20/80, and the 20/80 seems significantly easier to sand.

Using an unscientific fingernail scratch test, I would guess that the 100% material is about twice as hard as the 20/80 material.
I think the 20/80 material will work.

Thanks much to ddmckee for that trick !
.

 

[Jasonb]

Be worth trying it on plastic before applying a lot to a pattern as it is unlikely to bond as well as your wooden test piece. Also may not hold up when it comes down to staying in place between the fine print layers.

 

[GreenTwin]

Be worth trying it on plastic before applying a lot to a pattern as it is unlikely to bond as well as your wooden test piece. Also may not hold up when it comes down to staying in place between the fine print layers.

I think the 20/80 material would be a good candidate for spraying on a final light coat.
.

 

[Jasonb]

But its the thick heavy coats before that where the easier sanding comes into play.

 

[GreenTwin]

I can try it out on the dog.
Dog test #1 underway.
.