Big muller, little budget

[barryjyoung]

Does anybody know if the tilt on mullets is just so that the side opposite the door will empty? It seems to me that the blades would push out any remaining sand for the most part even if the floor of the muller was level. Does the tilt have anything at all to do with the mixing action? I am going to add a wheel and it seems like it will roll better if the muller is level.

Barry

[Harry]

The commercial mullers I have seen have all been level and the blades/wheels push the sand out towards the door. Mine is tilted way up because it just has a better action in the mulling this way (no wheel) though it would probably empty fine even if it was level since the sand works its way to the outside wall, with the big door you have I dont think you will have any trouble there at all Barry.

[dallen]

Barry, hi I'm sorta playing catch up with your thread (been in South America for the last couple of weeks) Olivine sand is a very find grained sand. Greensand is termonology of actually any sand that has water in it. If your building your muller to mix Greensand you can actually get away from having the wheel, all you need is something to blend the sand and break up the lumps that occur from Casting, and to help blend in the water that you will use as a binder.
Tilting the muller is done at peoples own discretion, if the mullers large enough I would tilt it especially if I was not putting in a door. with a door, mine empties out pretty good but I don't really completely empty it or haven't since I built it.

If your going to mix oil bonded sand, then put in a wheel, I guess I got pretty lucky with mine, and ended up with a muller that will handle a lot of material without slowing down, the wheel needs to be either spring loaded, or heavy mine is an old gear that is almost 8 inches in diameter and 1.5 inches thick with a 2.5 inch wide section of sechudel 80 8 inch pipe welded onto it for a tire, its mounted on a planter tire wheel bearing, I don't have a number or remember where I ordered them from. Its pressed into the wheel and mounted on the swing arm, which is set to allow about a inch of gap between the tub bottom and the wheel.

I used a 12 inch long section of 24 inch pipe because its what I had.

The first batch of Oil Bonded Sand I did was an 80 pound bag of 100-120 silica sand with about 3 or 4 pounds of petrobond powder in it, with a pint of oil and a half bottle of cat, I ran this stuff in the muller for I don't know half an hour and its compared to the sample Harry sent me about the same in consistency. I have one scrapper that runs the wall with a couple of knock down bars welded inthe top edge of the tub,

If you want to see what I throwed together I have a thread in here just look my name up and you can find it. I sorta used Steve Chastians book as a starting point, but went more my own way because of not wanting so do some of the things that he did.

It works thats all I care about, I have some minor details to finish if and when I get home, like a shelf to set a bucket or tub on to catch sand as I empty it, and a shelf or top so that I can ram up patterns on top so I don't need a seperate bench. and of course diffenately a coat of primer, or maybe not who knows, I may even paint it, some gaudy color the neibghors won't like.

I did some molding in it with it at a 100 rpm with just a big beater paddle in it with greensand, it totally amazed me with the muller how little water is needed when you get a good through mixing. I would squirt water out of a spray bottle with it running and about the fourth squirt the sand would just stand up and be moist all the way thru.

David

[barryjyoung]

Harry: Thanks, I kind of suspected maybe the big reason for tilting the muller was for emptying. I will make this muller level. It will have a scraper and a squishier blade. If I need to I will add a wheel later. I welded the scraper into position this morning so it will not be much longer before this baby is running.

David: Thanks for the effort on that epic response. I am using Olivine so I won't be messing with oil for a while or Petrobond either. Hopefully my scraper and squishing blades will be sufficient.


Barry

[dallen]

damn did it again, lost a post i was working on,, Your welcome Barry, if like me you don't make casting a life time ambition. I plan on fitting either some Bar Grate, or s section cut from a 2 "shaker screen to fit the top so I will stop sticking my hands in and grabbing a handfull.

The thing that caused me to make the switch was weather in Oklahoma, you could mix up your sand today make one pour put the sand back in the tub, the next day if you needed to make another pour the sand would be too dry. So Oil Bonded Sand.

Plus I found a couple places to get the petrobond powder Harry being one. I have also locate a place that sells the petrobond two powder at two dollars a pound, only catch there is you gotta buy a bag, but you need no catalyst, just oil.

one thing to be cautious of is to make sure that the door of your muller is high enough so that you can get a bucket, tub, or wheelbarrow under it, also make chute or trough call it what you want, so the sand is directed where you want it.

The sand is pushed out of my muller as the scrapper comes around so I get a big handfull everytime the wall scrapper comes by.

The big AZZ Scoop that Harry has can be had from a feed store, if you want and cant find let me know the one I got was about ten bucks, I don't know where Harry got his, mine came from the lumber yard which sells livestock feed.

post a video of your muller when finished with it running so we can see what it will do.

[barryjyoung]

David: I am a Journeyman Machinist. The chances of me putting my hand in a running muller are somewhere between none and none. I learned respect for rotating machinery a very long time ago.

Here in the Pacific Northwest we have lots of weather to keep the sand damp. I understand in a dry climate using oil based sand though, that makes great sense.

The plan is to have the muller dump into a conveyor that lifts the sand to a trommel above the molding bench. To heck with lifting a five gallon bucket of sand. Lifting things is for young people.

What is the scoop for?

I promise to post a video when the muller is up and running.

Thanks for your help.

Barry

[Harry]

You want a nice big scoop for moving sand, filling the muller, flasks ect... We have a little feed store down the road (about 20 miles) and I saw these metal scoops in there, they are used for hay cubes and such. One thing I really like about it is the handle is over the scoop itself so center of gravity is under the grip rather than hanging off the end. It will pick up nearly ten pounds of sand at a time so that saves a lot on the wrists.

On the sand choice always being ready is one good point but for me the other was simply getting a good mix. I was never able to to get my greensand good enough to even come close to performing the way the petrobond mix does but then that was I am sure my own fault in the mix.

David, I dont remember where I had read it but my impression was that even though the petrobond II says you dont need catalyst adding it helped. Doesnt much matter for you with that 5 gallon pail though At $2 a pound buying a bag isnt too much of a hurt even with shipping. A 50 lb bag will make a nice heap, my bench will hold about 1000 lbs of sand which is nice because once used (especially on larger parts where a lot of heat is transferred into the sand) it needs to cool down and working by myself 1000 lbs is about all of the molds I want to do in a day so it works out pretty good.

[dallen]

Harry I don't need a thousand pounds of sand, not going into production. I Build the muller so I could mix my sand, actually the greensand that I have worked really well after being ran thru the muller, becasue I could get a even blend on the water and not have mud balls in it. But I had already ordered some of the petro powder before building it, and I had heard all these storys about how good the oil was over the water.

You know I'm not so sure anymore, if you look at the real reason that Petrobond was developed, it was to speed up production. Granted there are some other advantages to using it, and I probably won't switch back except for that one off casting where nothing else but greensand will work.

As for buying a bag of powder I have been thinking about it, but it would only be one of those things that I would do if someone else wanted some sand mixed up and didn't have a muller to handle it. I do think that a person needs a wheel to get the pressure onto the materials to bond them, but the first few minutes are not doing anything but mixing the sand and powder together its after the oil is added that you need the pressure.

I should be home by this weekend maybe I can get things dug out and fire up and pour some cast iron and see how the oil sand will hold up. I know from what little I have done with aluminum that it comes out clean when I shake out, very little hanging on. I do get a burn back into the sand of about 3/16 inch is this pretty much what you see?. Haven't had the sand hot enough yet to have smoke come up thru the sand while rammed up in the flask except on that fan blade that I vented.
David

[Harry]

The amount of burn will vary some with how thick the section is but yes about 3/16" sounds close. Dont be shy about selling the mixed sand if you want to offer folks a better price on it, I dont sell it to try and make money so it will not cut in on me. Figure about 40 lbs in a large flat rate box and shipping around $15. The other option would be offering the petrobond clay, oil and catalyst. The price you mentioned on being able to get it at is less than what I pay for it.

Barry, missed the conveyor/trommel mentioned above. Sand handling would really be great, I had thought about several different ways of moving sand around and will eventually try some out. Along with a conveyor would be a screw or bucket elevator.

[barryjyoung]

Yesterday was good. Even though I had a meeting and web hosting tragedy to take care of, I was able to get a couple of hours in the shop. I got both the scraper and squishing blades welded onto the axle inside the muller. Also, the top bearing which keeps the axle from moving around inside the muller as it alternately hits sand and air was successfully welded into place. The motor mount was FINALLY adjusted precisely enough to weld into place. I was able to run the motor with the final chain drive not falling off all the time. It still is not as smooth as I would like it to be but it runs and I am sick of messing with it. I also started what I call the chain tray. Because the chain is so long, it tends to sag enough to occasionally drop off the sprockets even when properly tensioned. To counteract this tendency I made an angle iron tray that kinda sorta acts like a chain guard that is close enough to support the chain. I will attach that today and put legs on this monster. I also started making the trommel. I drilled out the spoke holes in the three 20 inch bicycle rims to .189 with a #12 drill. then pop riveted the 1/4 square screen material onto the inside of the rims with 3/16 x 1/2 inch aluminum rivets. Now I have a tube that can be supported on cheap casters and powered by a vee belt in the center. Still need to build a wooden frame for that and install it above the molding bench.

Harry: Thanks for the hint on the scoop. I have been using an entrenching tool to move sand around and it does not actually capture the load, too much falls off the sides especially when you move. A grain scoop makes excellent sense. I need more quantitative rather than qualitative descriptions if I am to understand your answers Harry, you said in a previous post that your cast aluminum machines better, you said in this post that Petrobond makes a better mix. What about the machining and the mix is better? Better how?

David: I need to wait and see what the entrance to the conveyor looks like before planning the chute, but it is on the list.

Barry