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Old 05-26-2011, 09:05 AM   #1
Kevin Steel
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Making Stones

Im getting ready to make some stones, and have a few questions.

Is it necessary to put some kind of strengthener (like concrete fibers) in the mix? Or does just straight concrete hold up well to being dropped repeatedly?

Has anyone experimented with making thier own lightening inserts, or heavy inserts? If so what materials did you use, and where did you get it?
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Old 05-26-2011, 09:36 AM   #2
Justin Heller
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Re: Making Stones

Fibers are not necessary at all, 5000 PSI concrete will hold up just fine. I have routinely dropped mine on 3/4" stall mats and I'm more worried about the floor underneath.

For inserts, go to a local crafts store and buy the high density foam balls I usually find them in the floral area (where all the fake plastic flowers are). Put a hole through the middle with anything long, I use a long screwdriver. Use a decent strength rope and a big washer to secure the foam ball. If you skimp on that part the force of the concrete pushing up on the foam ball will snap twine or anything weak like that.

No more than 48 hours in the mold is necessary, then let it cure in the open air for a solid week before dropping it. The longer it cures, the stronger it gets. The advantage of 5000 PSI is you get very fast strength, maybe 2500 or so in less than 48 hours.
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Old 05-26-2011, 09:38 AM   #3
Justin Heller
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Re: Making Stones

For heavy inserts, I tied up a bunch of 10 pound plates and suspended them from a garage rafter right in the middle of the mold as I filled it with concrete.
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Old 05-26-2011, 12:55 PM   #4
Gene Pires
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Re: Making Stones

interesting using 10lb plates to add weight. Any chance you could tell us the diameter and weight on stone so i can figure out how much weight it actually added over a pure concrete stone?

I am looking to make a 200lb stone from a 16" mold. According to slater, adding about 30# lead would make about a 200# stone. (that insert would be $40 to $55 plus shipping!)

I suppose comparing density of lead and iron would give me the answer.
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Old 05-26-2011, 01:05 PM   #5
Anson Castelvecchi
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Re: Making Stones

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Originally Posted by Kevin Steel View Post
Im getting ready to make some stones, and have a few questions.

Is it necessary to put some kind of strengthener (like concrete fibers) in the mix? Or does just straight concrete hold up well to being dropped repeatedly?

Has anyone experimented with making thier own lightening inserts, or heavy inserts? If so what materials did you use, and where did you get it?
I add 2 kinds of Fibermesh (micro & macro) to the 500PSI concrete I use to ensure a stronger stone. To make it lighter you can add perlite (used as block fill) at about 20-25% of mix volume.
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Old 05-27-2011, 12:43 PM   #6
Kevin Steel
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Re: Making Stones

Thanks for the advice. I found the foam balls at my local craft store, up to 10" . Its too bad that you have to put a hole in the mold to use it.
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Old 05-28-2011, 09:34 PM   #7
Kevin Steel
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Re: Making Stones

what about some kind of sealer?
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Old 05-29-2011, 05:00 AM   #8
Ben Moore
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Re: Making Stones

Dont seal them...ive never seen them come out good
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Old 05-29-2011, 10:20 PM   #9
Matt Thomas
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Re: Making Stones

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Thanks for the advice. I found the foam balls at my local craft store, up to 10" . Its too bad that you have to put a hole in the mold to use it.
You don't have to. What you can do instead is buy some thin wooden dowels and cut them to the diameter of your mold. So if your mold has a 12" diameter, cut the dowel into about 5-6 pieces each 12" in length. Now shove the dowels through the foam ball at all different angles and place the ball in the mold. The dowels will press on all sides of the mold equally and keep the ball in the center. It works pretty good.

Did I explain that good enough or is it still unclear?

Last edited by Matt Thomas; 05-29-2011 at 10:26 PM..
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Old 05-31-2011, 05:48 PM   #10
Kevin Steel
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Re: Making Stones

Makes sense. All the pictures of foam balls for stones are shown with dowels in them.

Today I picked up 5000 psi concrete with fibers pre-added. pretty stoked for the new toys!
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