As you will quickly notice this dirt and rock sifter is very basic and not terrifically inventive. On the other hand, it does demonstrate how folks can turn a bit of trash into a bit of treasure. It’s crude but cheap...just like me.
The Shopping Cart:
Obviously, don’t rush off to your nearest grocery store to slink away with one of their pristine carts to replicate this project. Theft of private property is a clear violation of Rule 19 of The Instructables’ International Peace Accord. Fortunately, there are a number of places you can seek out a usable cart without committing a crime.
*Ask at your local store or market if they ever part with damaged, broken or obsolete carts.
*Ask at your local landfill. Clean up crews often take “ditch carts” to the local landfill and some landfills will separate out usable items (bikes, carts, etc.) and set them aside for short periods of time for re-purposing.
*Ask at your local metal recycler. They too might allow you to salvage a ditch cart before it goes in the crusher.
*Abandoned and unmarked ditch carts. Around our area abandoned shopping carts can regularly be found dumped in ditches, river beds, roadsides, trash heaps, industrial sites, parks and dozens of other places where they create grade A eyesores. Personally I would not take a cart, even a clearly abandoned one, if it was on private property or if it was marked regarding store ownership and it was not damaged. You can make your own judgement call regarding those fine points of law and morality.
For use as a stone sifter, carts can be pretty beat up and have missing wheels, bars or other integral parts. As long as the basket has enough metal structure to support the hardware cloth you will be installing, the cart can be put to good use. The cart I used was found along the roadside of an industrial park, had a missing rear panel and was not marked regarding store ownership.
I already had a yard cart for pulling behind my garden tractor and a wheelbarrow. If you don’t have these items you will need to improvise with some sort of wheeled wagon or simply let the dirt and separated stones fall to the ground or onto a tarp to be scooped up later with a shovel.
Other materials you’ll need:
A 3'x5' roll of 1/4" hardware cloth - $14 at Home Depot.
30-40 4" zip ties - $4.28 for 100 at HD.
A 2' x 2' piece of scrap plywood (size can vary a bit)
A 3-4' length of scrap 2x2 or 2x4
Step 1: Remove Rear Panel
Remove the back panel of the cart...the section below the cart’s push handle. Mine was already gone. If your car has a solid rear panel you will need to cut away the bottom 2-4 inches across the width of the cart so that the stones/rocks can roll out. You can also cut away the entire back panel if you prefer. If your rear panel is the hinged fold-up type, you will need to cut it away from the cart at the hinge points which leaves the entire back of the cart open.
Step 2: Install Hardware Cloth
Cover the bottom, front and two sides of the cart with one continuous piece of 1/4" hardware cloth (screening). You will want the cloth to lay as flat as possible against the bottom of the shopping cart and bend as sharply as possible at all the corners to run up the front and sides of the cart. This will require that you cut the mesh screen at about a 45 degree angle at the two front corners. As you push the wire down into the cart, you can overlap those front corner pieces. It is important not to leave any gaps or open spots in the hardware cloth where stones can get behind or where you might catch your hand or glove on exposed wire ends. Use a length of 2x4 to push the mesh down firmly into all the edges and corners of the cart’s basket. Then use 4" zip ties to secure the hardware cloth to the wire framework about every 4-6 inches on the bottom and sides of the shopping cart.
Step 3: Tilt the Cart
If you are using a yard trailer/cart, put the shopping cart into the yard cart and then lift the front wheels and prop them up using a length of 2x2 or 2x4 laid across the width of the yard trailer as a cross support. Hold the 2x2 in place with pony clamps. I later raised the front of my shopping cart three more inches (to make the stones roll easier) by clamping a couple 2x4 blocks under each end of the cross support. The higher you tilt the front of the cart, the easier the stones will roll out.
Step 4: Build a Chute
You will need some sort of chute to direct the sifted stones into a separate wagon, wheelbarrow or ground pile. I used a scrap of 1/4" plywood and screwed a length of 1x3 on each side of the board to form a trough to keep stones from rolling off the sides. The chute is held in place with a bungee cord providing for easy removal whenever the wheelbarrow gets full of stones and needs to be emptied. The bungee hooks into holes drilled on each side of the chute (arrow).
Step 5: Set It Up and Sift
It should be noted that this is not a powered sifter. There is no mechanism to shake or vibrate the process. I shovel the material in through the back opening, and when I have 6-7 shovel fulls in the basket I roll the stones around a bit with my hand and then push them toward the chute where they roll into the wheelbarrow. As they roll, the dirt and sand drops into the yard cart. The stones roll down the chute into the wheelbarrow. It takes a bit more effort than a powered sifter but it is much much easier than my previous flat box type sifter.
It should also be noted that this particular way of sifting produces fairly pure “dirt” in the dirt pile but does not produce pure stone in the stone pile. Anything larger than the 1/4 screen will end up with the stones. So if you want pure stone, without grass, twigs, weeds, bark, small critters or other miscellaneous junk, you will need to either wash the stones or run them through a different sort of process. Also, a small amount of dirt/sand does escape and roll down the chute along with the stones.