# Stone Casting Method for turntable or...



## Nutz-n-Bolts (Aug 12, 2010)

I would like to put a 41 inch turn table in soon. Since the table will be in the ground and not on elevated bench work I wanted some thing weather resistant and durable. I also wanted the pit to look as if it were constructed from stone. Not wanting to end up with a 500 Lb piece of garbage. I decided that I should test my method. The first picture shows the mold.









I sealed all the seams with a bead of glue. It held up pretty well for being what it was. The next picture is of the surface preparation. First I drew the pattern of the stone on a piece of chipboard. Then covered the piece of chipboard in double sided tape. Then I cut lengths of string to lay around sticking it in place on the tape. For the short vertical cuts I used some telephone wire cut in to bits. I used a masons string line for the horizontal cuts. 











Now I have to apologize I got a little excited and missed taking a picture. After getting all the stone cuts in place on the mold the next thing I did was to take a pice of tinfoil and press it in to each of the stones with my fingers. I tried to get it dow to the tape right up to the cut so you have to work from the middle out, since it use extra foil to go over the string and wire. I did not take a picture of the finished piece before I taped it into the mold. Sorry, but you can see it ok in this picture of it installed in the mold.










Now if this were the actual thing I would build the center out of (Lexan?) and or wood, and then apply the tape and "cuts" directly to it. As for the finished thing I think it has a lot of promise. I forgot to spray the foil with Pam cooking spray and most of the foil stuck to the concrete but it looks cool. I just used Quickcrete to pour it and think a more refined concrete might work even better. Any ideas on what to use? I think I will find a larger wire to do all the cuts with. The string frays at the ends and the phone wire was a bit too small. The string is just the right size. I think I'm going to try the full size one some time this year. I'll be sure to post it. 










Finished From the right:









Finished from the Left:


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## steam5 (Jun 22, 2008)

They look great! I have never cast anything before, so I can't add any tips. 

Great Work! 

Alan


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## Totalwrecker (Feb 26, 2009)

I like to do castings with Cement All, it's more expensive, but a lot cheaper in the 20 lb box than the 10. 
It is very low shrinkage and strong. 

How are you going to secure the sections together? 
Looks good and I kinda like the foil look too! Reminds me of industrial paint. 

John


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## Nutz-n-Bolts (Aug 12, 2010)

Thanks Guys, I plan to do the whole thing in one big cast. Finish diameter of 47". I will have to flip it over strip it of the mold and position it after it cures. The base will be 3" thick with lots of rebar that will lead up n to the walls as well. I'll have to look for Cement All. I thought of introducing some fiberglass to the mix too.


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## Madman (Jan 5, 2008)

Try using sand mix. It's still concrete but without the pea gravel. You won't get as many voids or honeycomb, as it's called when pouring concrete. I like the look of the finished stone wall. The string and foil idea is a good one. The only other suggestion I would have is try and calculate the weight of your finished product. A 47" diameter piece of concrete may be quite heavy.


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## Randy Stone (Jan 2, 2008)

I used to work for an overhead bridge crane company. 

One of the companies that we serviced produced cement light poles. 

They would pour the concrete in the mold and then use a machine that vibrated the mold to fill all the voids. 

You might try using something to vibrate your mold to help fill the voids


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## Ron Hill (Sep 25, 2008)

Randy, will the turntable be large enought to use lauan or masonite? I have used luean to cast bridges and it works really good. Also WD-40 is better than Pam spray to keep the concrete from adhearing to the mold. 
Ron


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## Totalwrecker (Feb 26, 2009)

Just use a stick to tamp the pour... you liquify it with up and down motions and it flows into the corners and releases bubbles. 
If you are going to flip it over, I'd also dress the top.. er soon to be bottom, with trowels and floats to even the thickness all around and to smooth out the surface. Makes leveling the unit easier. 

John


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## SE18 (Feb 21, 2008)

concrete casting is fun


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## Nutz-n-Bolts (Aug 12, 2010)

I did bang on the form a bit with my hands to get the air out, But I did not want to risk weakening the flimsy cardboard I built it out of. When the real one is being cast I will vibrate the solid wood form with my orbital sander. I was thinking about a sand based concrete too. I know this thing will weigh in at around 300lbs But I plan to cast it right next to where it goes then I will flip/roll it over right into the spot where it will go. I'll bring out my engine crane to do the heavy lifting leaving me free to finesse it into position. It will also have a drain cast into the bottom of the pit that will flow into the french drain system below. Your right SE18, it is fun and I'm pretty excited about the real one now.


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## Madman (Jan 5, 2008)

Posted By SE18 on 06 Jun 2011 05:54 AM 
concrete casting is fun



*But concrete is not*


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## SE18 (Feb 21, 2008)

you could slather on some mortar or thinset to connect the sections. You'd need to smooth the seams as well.


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## DKRickman (Mar 25, 2008)

Why not build the mold so that you can cast the turntable pit in place? Just design it so that you can pour in from the top instead of the bottom, and add texture there if you need to. That way you don't have to move a huge concrete casting. At 300# or more, you're running the risk of doing serious damage to yourself or your tools trying to move it - let alone flip it over! And of course, there's a high risk of breaking your casting as well. I would strongly suggest you consider either casting in place, casting in sections, or using some lighter material. 

On the lighter material side: Why not cover the interior of the mold with a skim coat of mortar or cement, and then fill the main void with expanding urethane foam. Even papercrete should be a bit lighter. You can mix all sorts of things in concrete in place of aggregate - paper, styrofoam, pearlite, etc. - all of which are lighter than rock. You don't need the ultimate strength of proper concrete, just the weather resistance, right?


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## John J (Dec 29, 2007)

I have had sucess with a vibrating orbiltal sander places against the side of the form. 

JJ


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## Nutz-n-Bolts (Aug 12, 2010)

I'm definitely going to cast it in one piece. I don't want to have to precisely aline separate pieces and then cover the joint. Also I think if the ground were to settle slightly it could stress a joint and crack it. One large casting/slab will take that abuse. As I said I will be putting a lot of rebar/mesh in it and with a lip 6 inches thick at the edge the Casting will be plenty strong not to break while I handle it. I'm no stranger to heavy items and moving them. Like I said I'll get my engine crane (2000 lb capacity) for the flip. If I don't like that, I'll get my 8 ton track loader out to move it!







I've also got a fair amount of concrete experience. I've poured over 60 yards during the renovation of our house over the last 10 years.

I did consider pouring it in place Right side up, but I don't feel that I can control the surface finish as well that way. In that orientation Th air bubbles would want to rice to the exposed finished surfaces. With the mold upside down I just need to make all the mold surfaces to the finish I desire and the fill and finish only the bottom by hand. I think it will yield much better results this way and I'm really not that worried about the flip and position. It's small potatoes compared to some of my projects.


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## jake3404 (Dec 3, 2010)

I think your fine casting it in one piece. It seems you have the right equipment to lift it, because it will be heavy. But, like you said this turntable isnt going to be supporting a large amount of weight so if it shifts, the whole piece will shift. The rebar will definately help and I think using the fiber is even better. 

One thing the fiber might make the finished face not look smooth. What I suggest is pouring the Sand mix (again good idea) in two pours. Pour a thinker consistancy mix first and try to push it into all the detail work. Then lay the fibour material, then pour the rest of the mix in a more thinner consistancy. I was thinking by pouring in two sets and laying the fiber material in between, it keeps it out of the detail work and messing up the look. I really think you need the fiber just to keep the overall strength of turntable and to reduce cracking.


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## Madman (Jan 5, 2008)

Don't worry about the weight.







With alittle thinking







you can move anything. Like you mentioned, you have the equipment







. Besides, hard work keeps you young. This just reminded me of a young guy I worked with years ago. He had some digging to do to install some sanitary pipe from his house to the street. So he was going to do it himself as he could not afford to hire some one. Nothing wrong with that. He said he had a mini back hoe all lined up to rent for the day on Saturday. I said, John, what in God's name do you need that for, dig it by hand. Your ground is sandy. besides, if you run into something with a shovel, you won't do as much if any damage to it. John wasn't having any part of it. Monday morning, John arrived for work looking like he had been run over by a train. What happened John, I asked. As John got closer to the street, it was getting late. So rather than finish the dig by hand, he used the back hoe. John managed to pull, not only the township's sanitary up, but also the water department's pipe. And the rest of the story is up to you to piece together.


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## SE18 (Feb 21, 2008)

I wouldn't worry that much about air bubbles. You can always smear some Portland or something over any that arise 

as for lifting, you can jury rig a 2x4 tripod and make a quick hoist using rope and pulley 

Dave


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## Nutz-n-Bolts (Aug 12, 2010)

Dave, No need to jury rig when I have a perfectly good engine crane. 

Dan, Every time I see some one dig into lines I have to laugh.







It's suppriseing how often it happens. Don't worry about me. I replaced the water line all the way to the curb box my self. At the point both the Water and gas were exposed. I also connected our house to the city sewage for the first time in it's 120 years of life. I know very well where all that stuff is and don't plan to be any where near it.


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