How to make an Atlas Stone (Part 1)
For the Strongman Competitions, cousin Ben and I have had to make a few Atlas Stones. They are the large concrete balls that the competitors have to lift.
Here is the first stage of making an atlas stone - making the mold. The second part will come once we have made the stone.
First you need to calculate the size of the stone. The mass is approximately :
M = 3067 Pi R3
So in our case, R = 0.2653m and M = 180kg
Then get two sheets of timber and bolt them together. Cut a circle of the appropriate size :
(click to enmagnify)
Inflate an exercise ball to the correct size. Do not over-inflate the ball as you will end up with a waist-line in the stone and it will be very hard to get out of the mold. It should be a loose fit in the hole in the wood.
Ideally, the ball should have no “ribs” on it (we lost our rib-free one and could not get another one). Cover the ball with mold-release :
Support the timber on something solid :
Insert the ball and support it from beneath. Make sure that the ball is exactly in the middle. If it is sitting too high or too low, the stone will be hard to get out of the mold. Have the ball inflation hole at the top for easy access.
You will need a ring of plastic (we used a short length of 150mm PVC pipe). This will form the opening through which the concrete is poured.
Put on a layer of fibreglass, using the necessary precautions. Don’t fibreglass over the bolts.
Roll out any air bubbles. Remember to not swallow the fibreglass roller (this is a common mistake).
Fibreglass the ring in place and add another layer or two of fibreglass to the whole thing :
Allow the fibreglass to set. Tip the whole thing over and fibreglass the other side. Allow the fibreglass to set. Deflate the ball, undo the bolts and separate the two halves :
How to Make an Atlas Stone (Part 2)
How to Make an Atlas Stone (Part 3)
How to lift an Atlas Stone
March 20th, 2007 at 10:10 am
One must therefore make sure that one aligns the air valve with the concrete filling hole? Have you ever made the mistake of not doing that?
March 20th, 2007 at 3:12 pm
I’m guessing the ball just gets cut out and the alignment of the airvale with the concrete filling hole is inconsequential?
Dunc.
March 21st, 2007 at 6:49 am
Newman is right. The air hole needs to be at the top. There are actually quite a few small things which are important, but which I have left out.
April 7th, 2007 at 6:57 pm
[…] Once you have made the mold, the next step is to pour the stone. Firstly, you need to wax the mold to make it easier to get the stone out. I just use car polish, but there are many alternatives. […]
April 8th, 2007 at 1:30 pm
Looks very simple. Nice post.
May 9th, 2009 at 9:51 am
[…] Atlas Stone Part I and Atlas Stone Part II […]