Big muller, little budget

How to condition loads of sand to ease making molds.
barryjyoung
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Big muller, little budget

Post by barryjyoung »

I am building a muller along very similar lines to the one shown at backyard metalcasting made by George VonTorne.The starting point was slightly different as I am starting with a water tank that is around 28 inches in diameter as opposed to a propane tank. I went through the extreme hassle of making a door very similar to George's but was able to simplify matters a bit by dispensing with the wire latch. I welded two de-sta-co clamps on instead. For the hinge I simply welded a hinge in place rather than make one. I was lucky enough to find a 1750 rpm 1/2 HP motor with a 29:1 speed reducer from craigslist. That gave me plenty of torque at 60 RPM. I am further reducing the speed to 30 RPM with a 1:2 bicycle chain and sprockets from a kids bicycle.I bought a lawnmower wheel at Lowes to get some cheap flanged ball bearings. While at Lowes I bought a 1" black pipe nipple which the bearings would not quite fit into then I bored the pipe on the lathe to just allow the bearings to be pressed in with a light press fit. The lawnmower bearings have a .506 inch ID which fits a 1/2 inch rod with a slip fit. Not sure yet if the axle will be a drill rod or a piece of all thread. For the outer blade cylinder a 1 1/4 inch pipe with a plate welded to the end is a nice fit over the 1 inch bearing holding cylinder which is welded to the tack top. Basically the design is Georges, but I tried the conduit idea without bearings and could not get it to work at all. The column welded to the tank would flop around and flex to no end. That is why the bearings had to be added and the whole mechanism stiffened up with pipe. There is a possibility that support may be needed at the top of the column. Won't know that until the thing runs correctly the first time with sand in it. I have not decided yet whether to add wheels or if blades will be enough. I will try to post pics of the in progress work tomorrow.

Barry
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Harry
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Re: Big muller, little budget

Post by Harry »

Do you use oil sand or green sand?

The 30 RPM sounds great and the 28" diameter will be a good sized batch, how deep is the bin? I used blades in mine, they just stretch out across the bottom of the bin and a vertical on the ends to scrape the sides. I also added a striker plate so as the sand is carried around it gets smashed and knocked off the blades.

David has just built a nice muller with a wheel in it, the action in his videos shows a good smearing motion going on from the wheel.

It is my belief that for batching petrobond a wheel is a good idea to get the best distribution of the clay particles on the sand during that initial batch. If you use a ready made sand like I do then all you really need is to break up the burned bits and mix them back in. I also think the wheel would be a little faster, mine usually runs 5 to 10 minutes on a 40 lb batch to get all the bits broken up.

When I build my next muller it will have a wheel.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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barryjyoung
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Re: Big muller, little budget

Post by barryjyoung »

Harry wrote:Do you use oil sand or green sand?

The 30 RPM sounds great and the 28" diameter will be a good sized batch, how deep is the bin? I used blades in mine, they just stretch out across the bottom of the bin and a vertical on the ends to scrape the sides. I also added a striker plate so as the sand is carried around it gets smashed and knocked off the blades.

David has just built a nice muller with a wheel in it, the action in his videos shows a good smearing motion going on from the wheel.

It is my belief that for batching petrobond a wheel is a good idea to get the best distribution of the clay particles on the sand during that initial batch. If you use a ready made sand like I do then all you really need is to break up the burned bits and mix them back in. I also think the wheel would be a little faster, mine usually runs 5 to 10 minutes on a 40 lb batch to get all the bits broken up.

When I build my next muller it will have a wheel.
Hi Harry:

I have Olivine sand. I think that is green sand. Not sure though, the guy at the foundry supply picked it out when I told him what I was trying to do.

The bin is about 10 inches deep. My next posts will have pics of the door and my motor and speed reducer. Maybe I should add a wheel now. I think you know what you are doing based on your posts.

Barry

Yes, I saw your excellent post on your muller build. Very nice job especially on the transmission.
barryjyoung
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Re: Big muller, little budget

Post by barryjyoung »

Some pics of the muller build so far. The door is finished and shown open and closed. The motor and speed reducer are once again together (when I bought them the guy had taken them apart and lost the key that keyed them together) Luckily, I buy all the assortments when they go on sale at HF so I had a box of assorted keys.

Barry
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Jammer
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Re: Big muller, little budget

Post by Jammer »

Your like me, I have about 10 things going at once.
quando omni flunkus moritati 8-)
Heimo
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Re: Big muller, little budget

Post by Heimo »

Jammer wrote:Your like me, I have about 10 things going at once.
correction, I think that describes most of us here, running 10+ projects in parallel seems to be the norm among most of us
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Harry
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Re: Big muller, little budget

Post by Harry »

From the size of that door it looks like it will empty right quick thats for sure. On the sand if you add water to it to wet it up then it would be considered greensand and is made with either natural clays found along with the sand or by mixing bentonite in with sand and water.
Jammer wrote:Your like me, I have about 10 things going at once.
Seems there is a lot of things going on in this situation. I know for myself a little ADD probably plays a part then also the waiting for the next piece of the puzzle to be able to move forward. This does allow for plenty of thought in moving through a project though and a well thought out idea has a better chance of flying most times. Also having many things going at one time challenges the mind and when pressed it will do some of its best work.
barryjyoung wrote:I think you know what you are doing based on your posts.
That could be subject to debate... In the real sense of the trade I am barely an apprentice still soaking up whatever I can. As far as my observations on the sand and the need for a wheel this is based on looking at how commercial machines are built and my own past experiences and I just feel having it in there will give a slightly better mulling action than without with the big plus for me being in speeding up the amount of time it takes to reprocess sand after casting because even if I had a large "real" muller I would probably still buy my sand ready made since I have a good source within a reasonable driving distance. By the time I price out sand, clay and oil then haul or ship from various locations and mix it myself the few cents saved dont add up. The mullers my supplier uses are huge 500 lb capacity machines that really do a number on that initial batching.

Now Bob mixes his own sand and he is without doubt at the Mater level in this craft so I could easily have this all upside down or it might be that his situation is different by geography and the individual components are easier to come by for him.

I am also one who tends to dismiss the minor costs more easily than most people. This probably makes me a not so good business person as I have often been told watch the nickles and the dollars will watch themselves. This is where I differ in that I see running the foundry as labor, I can keep all of my costs easily inside of $20 per lb and sell products at $20+ per lb so costs are 10% and labor is 90% which makes me ever on the watch to save steps and speed up the labor and not tend to worry much about cost.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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barryjyoung
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Re: Big muller, little budget

Post by barryjyoung »

Harry: I have a rule. I never make what I can buy for a reasonable price because my time is scarce. I was unable to afford a CNC machine with the travel I wanted so I had to make it. I could not buy a foundry furnace so I had to make one. I could have made foundry sand, but I was also able to buy it, so I bought it. I could not afford a commercial muller so I am making one. I looked at snap flasks but nobody makes one like I want which can be bolted together in different configurations so I am making some. The "If I can buy it I don't make it" rule has served me well. I used to envy people who had more time than money, now I wish I had the time I used to have because it takes so much time to get the money that I am left wanting for time. We are two years of weekends, summer break (I am a teacher), Christmas break etc. into this project and it is now finally nearly done. That is two years of not sitting on the beach or watching movies or going to the zoo. It takes a long time when you have to work. That is why our time is valuable.
barryjyoung
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Re: Big muller, little budget

Post by barryjyoung »

Jammer: Nope, for the last twelve years it has been one project for me, making cameras. Starting with nothing and living in a studio apartment twelve years ago, I have finally bought a house which was essential to having a place to work, a woodworking shop that is extremely capable, a machine shop of my own with enormous capabilities and now a foundry. All of this was to make cameras. It works for other things, but the one single goal all of this time (and in fact 30 years back counting my design efforts) was to build cameras. I even became a machinist so that I could learn how to do the machine work on cameras. So I have but one project in mind as I have for these many years. Rather, I have many projects with one single goal.

Barry
blindpig
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Re: Big muller, little budget

Post by blindpig »

Hey Barry,
Hoping not to steal your thread but I gotta ask.....Would you describe your camera? Maybe start another thread about it.....
I retired from a photography career lasting over 40 years and built a lot of custom equipment along the way.
My time preceeded the digital equipment now being used (and would be mostly considered antique now for sure) LOL.
Keep up the good work,
Don
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