Darren’s Diatribe

Now that you have made your Atlas Stone, you will have discovered that they are really, really heavy and hard to lift. I did warn you about that ! Now you need to know :
1. How to make a lighter Atlas Stone
2. How to lift it
3. How to get rid of the too-heavy Atlas Stone

Making a lighter Atlas Stone

One option is to make a slightly smaller mold. This is a hassle and expensive. The simplest way is to put a foam ball in the middle. The amount of weight a foam ball “removes” is equivalent to the weight of an equivalent sized stone :

M = 9635 R³ kg

So adding a foam ball of radius 10cm will remove 9.6kg of weight.

The foam ball will float, so you need a means of holding it down while the mortar sets. A PVC tube should be enough.

(click to deshrinkify the image)

Put mortar in the bottom of the mold. Put the ball in and put the other half of the mold on. Fill with mortar.

Place something heavy on top to hold the foam ball down. It will need to weigh more than the amount of weight displaced by the foam ball.

When the mortar has set, cut the tube off below the surface of the mortar (using a Dremel or similar tool) and fill the hole with some more mortar. Allow to set and smooth off the top as for a normal stone.

Making a Heavier Atlas Stone

The easiest way to make a heavier Atlas Stone is to put a lump of lead in the middle. In this case, you will need to have a means of holding the lead up while the mortar sets so that the lead does not sink.

The amount of weight that a ball of lead will add is approximately :

M = 37860 R³ kg

So, for example, a lead ball of radius 10cm will add 37.9kg of weight.

Making an adjustable Atlas Stone

I wanted to have to have a single stone which I could adjust the weight of, rather than having a series of stones. I made a stone with a tube down the middle into which I could put some additional weight. For the tube, I used some 150mm (6″) PVC drain pipe cut to just fit inside the mold. I blocked off one end with wood.

Before making the stone I made two concrete “slugs” which could slide into the tube to add extra weight. To do this, cut some 150mm PVC pipe slightly shorter than half the length of the tube which is going through the stone. Make two cuts along the length of the pipe to remove a strip about 15mm wide. Squash the tube to close the gap and tape it together with duct tape. This gives a tube slightly narrower than you started with. Fill it with mortar and allow it to set. To remove the slug, take off the tape and it comes out easily. Repeat for a second slug.

To make the stone, put the two concrete slugs into the tube which will be in the stone. This will stop the tube from floating when it is in the mold. Fill the bottom half of the mold about 3/4 full of mortar (like was done to make a light stone above). Put the tube in the mold horizontally. The tube should be half above where the join will be and half below. Put the top of the mold on and tighten the bolts.

Fill the rest of the mold with mortar and finish as for a regular stone.

You may want to consider using some steel mesh to reinforce the stone. Having the tube through the middle will weaken it a bit and you run the chance of it breaking. To do this, wrap the mesh around the tube before putting it in the mold. You will need some sort of spacer to keep the mesh away from the tube a bit.

Disposing of a too-heavy Atlas Stone
Here are a few ideas for what you can do with a stone you can’t lift :
1. Give it to a strong friend as a Christmas present
2. Use it as a garden ornament
3. Sell it on eBay
4. Dynamite
5. Paint it like a beach ball and wait for someone to kick it

How to Make an Atlas Stone (Part 1)
How to Make an Atlas Stone (Part 2)
How to lift an Atlas Stone
See also Making an Atlas Stone Using a Plaster Mold

This entry was posted on Wednesday, May 30th, 2007 at 7:44 pm and is filed under Make. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.