My muller build

How to condition loads of sand to ease making molds.
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Harry
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Re: My muller build

Post by Harry »

Just take a handful of the sand I sent you and slam it down on a coin to get an idea of what it will do David. Dont even need to pour it to see the kind of detail it will pick up.
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Jammer
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Re: My muller build

Post by Jammer »

You could do like Murray does and cover the pattern with Petrobond and then back it up with green sand. That's what he did when making some belt buckles. I'm not sure, he may just scoop out the oil bonded and some of the green sand and pitch it.
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dallen
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Re: My muller build

Post by dallen »

I don't have to do that all I have to do is squezze it in my hand, I can get fingerprints in greensand if I am not carefull the sand that I use to blend it with is that fine grained and from the texture of the sample that you sent to me Harry its made from the same grade of material. still waiting on bearings for the wheel.
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
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Harry
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Re: My muller build

Post by Harry »

I was under the impression greensand needed to be coarser to vent steam. If your greensand is that good there might be no reason to move to petrobond. One of the benefits of oil sand is that when the oil gasses the volume of gas is much lower than water flashing over, water expands 1700 times in volume when changing from liquid to gas hence the need for copious venting. I never do any venting with my sand.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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dallen
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Re: My muller build

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on the flask sides that I have been pouring I have been putting open vents or I really should say risers to hide the fact that instead of poking a wire all over the pattern that with alumium nice and hot will leave hairs on your casting, I haven't done any venting, I think that on some of the first parts that I did I had spots where the water in the sand was causing dimples in the casting, or more accurately it looked like porosity bubbles but was only on the surface.

GreenSand has the distinction of being able to be made from all types of sand and loam, it actually doesn't have to be sand, but can be good topsoil loam if the organic content isn't to high and it has enough clay in it to bind it together. Nice thing about it is that I can go anywhere and get casting sand, (Sand, trade word gets lots of mileage) the only other thing that keeps soil from being used in casting is how Refactory is the stuff, it needs an alumina content high enough to keep it from melting when the molten metal is pour into it.

Since I got the muller to the point that I could mix the sand with it, I have seen an improvement in my castings apperance, and my ability to mold the patterns in a more repeatable manner. But the biggest area of improvement is the moisture, you would not belive how little water it actually takes to go from Almost totally dry sand, to sand that is ready to mold and with my limited experance probably to much water. I'm talking a five gallon bucket of sand is what it takes to fill the flask I am using to pour the flask pattern. It takes less them 2 cups, before I would not of belived it.

The foundry here in the city that does aluminum work mold strictly with SS and Sand, is what they told me, they don't mess with either oil or water bonded sand but I think they do back their molds with oil bonded sand.

The biggest reason I want oil bonded sand is so I don't have to mess with the water, oil bonded sand doesn't dry out, if I have some small part that I want to pour I don't want to have to go get everything out to fluff up the sand and mositen it up so it will stick together.

I know how much water expands, wait till you have to get rid of 4 or 5 percent of it in your aggergate and people are jumping on your back about not being able to run 400 tons an hour, 5 percent at 300 tons a hour is 15 tons of water, takes a lot of air to handle it,

If the moisture in the sand is not to high, and you have some place for it to run to, it will vent up your risers, Lost Foam casting has the same problems, specially when they coat with dry wall mud and don't add vents, I did a part in foam, when I pulled the casting out it was all swelled up in the middle from the foam not venting, whos fault mine I knew it should of been vented I also knew I put it in the sand upside down so it had a big bulge where there wasn't any sand to hold the metal when it got there.

If I was still trying to pour the flask sides without the risers, these let me know when i get the thing full cause I have started pouring with it inclined, I would have to use a vent wire a lot as I ram the sand up pretty hard, or I have to much bentonite in the sand, Also the sand has to be premeable enough so that the moisture has someplace to go to, in other words it runs away from the hot metal, I noticed on the last casting that I did that the surface of the mold was almost totally dry before pouring, I poured the melt in and the surface was like it had way to much water in it, but around the part the sand was dry for and inch deep.

I'm going to oil bonded sand just need to finish a couple things on the machine, and I wil be ready to try and mix it, get rid of the problem of dry sand when I want to cast, other reason is in the winter time I don't want to have to deal with frozen sand, Those ar emy two big reasons for switching, bone dry sand in the summer time, frozen hard in the winter, not all the time but it would be often enough to be a problem. But I have heard that Oil BOnded Sand doesn't like having moisture in it that it will make it unusable till its dried out.
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
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Harry
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Re: My muller build

Post by Harry »

Like I said before I have never gotten water in my sand and I would not recommend leaving it out where it could get wet. One thing, in the winter mulling up sand just before use can help a lot, if you think it is stiff now wait until it gets int eh 40s or lower, it wont freeze but it does get clumpy.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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dallen
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Re: My muller build

Post by dallen »

Well I was able to get some more done on the muller this morning after staying up untill two AM, had to take a beauty nap yesterday so I was up late. So I fired up the old lathe changed the chucks to the three jaw cause I didn't want to mess with the four jaw an what I was going to do wasn't very critical. I turned a stud out to mount an Idler sprocket that I had picked up the other day, it is mounted so that if need arises I can add a spring onto it very easy. funny how it seems the easy way eludes us till after we do things the hard way. Anyway Idler sprocket is mounted and feet are welded onto the legs so I can't push the legs full of my lawn.

I'm still waiting on the Bearings so I guess its gonna be tomorrow or later before I can get back to work on the wheel.

David
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
dallen
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Re: My muller build

Post by dallen »

Well I guess since I can't find where I put the picturre that I took of the four flask sides leaned up against one another in the floor,

So heres one that I took after I finished the machining and drilled and bolted them together.

Image
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
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Jammer
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Re: My muller build

Post by Jammer »

That's a nice looking flask. What is it, about 12"X12"?
quando omni flunkus moritati 8-)
dallen
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Re: My muller build

Post by dallen »

inside is 11 X 11 with it being 4 inches deep, after the milling machine got done with it the panels were 3 and 7/8", the wood that I used to make the pattern out of was 1/4 X 4 X 24 inches so it lost a little in the cleanup and what not, I tried to hold and inch on the ends for squareness and strength, it actually came out pretty square.
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
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