Introduction: $25 Vibrating Garden Sifter
This sifter is based on a fairly common “vibrating” design with a few semi-unique features. The sifter is built for separating stones from dirt/soil and therefore may not be the best design for sifting compost or other specialized materials. But if you want to separate good dirt from gravel, rocks and clods, this is a viable option.
I am an incurable scrounger, scavenger and collector. My sifter was built using whatever parts and pieces I already had stashed away in the shop so it may not be an optimal design. The only exception to my “free” materials were the wire closet shelves which were purchased new for $25. So the project's price tag will rise if you need to purchase some or all of the building materials new. Assuming everything must be purchased, the total cost would be about $130 which includes:
Framing 2x4s (12 @ $3.63) $43.56
Cot Springs (6) $13.65
Wire Closet Shelves (2@$12.47) $24.94
¼” hardware wire $14.99
Used power drill $15.00
Dimmer Switch $ 9.99
Assorted hardware $ 5.00
Step 1: Step 1 - Wooden Framework
The sifter frame is constructed using hardwood pallet grade 2x4s which I obtained for free from a factory located in our industrial park. The factory sets out their unneeded wood materials every week or two for free pickup. It's first come-first served and I got lucky one day and loaded up 40 decent 8' 2x4s. These things are hard as rocks and require pilot holes for every screw or nail you put in them. But the price ($0.00) more than made up for the extra work involved. And I like the idea of recycling the wood. They are also about twice the weight of a typical 2x4 which is actually advantageous when building a vibration type sifter. Purchased 2x4s would cost 12 @ $3.63 = $43.56 Home Depot.
The sifter frame is fairly simple, just remember to use ample cross bracing to keep it square. You want to have the sifter box as low to the ground as possible (to make shoveling easier) yet high enough to clear any trailer and/or wheelbarrow you want to use to catch the stones and dirt. Final measurements will depend on what yard equipment you may be using.
Due to the weight of my raw lumber, I also made a wheeled pallet (seen in foreground of the photo) to move the sifter from one location to another. If you have some muscle living in your abode and/or you build with normal 2x4s, the frame should be easy enough to move without the need of wheels.
Step 2: Step 2 - the Shaker Box
The shaker box – is suspended at each corner using army cot type bed springs (see photo) which were scavenged and saved many years ago from an old bed frame we were tossing out. (Cot springs, 6 for $13.65 Amazon)
The sifting screen in the bottom of the box is constructed in two parts. Vibration type shakers often suffer over time from “wire droop”. The bottom screen wire stretches and settles with the weight of the dirt being tossed into it and eventually depressions are created where the material just accumulates and will no longer tumble down the screen and exit the box. To remedy this problem the bottom screen must be supported to keep it flat. I used two 16”x72” ventilated closet shelves (See photo - Home Depot 2 @ $12.47 = $24.94). The shelves are cut to the correct length and attached to the bottom of the shaker box. The shelves have a built in “lip” on the front edge which is designed to keep the shelf rigid. By placing the lips back to back at the center of the box, they act as a strong structural member to support the screen. (See photo) Around the edges of the shelves I used 1 ¼” square PVC fencing balusters from an old outdoor fence I had dismantled. (See Photo) Wood, staples or other suitable material could also be used to hold the shelves in place. The inside of the shaker box is covered with 1/4” galvanized hardware wire (Home Depot 1/4”x 24” x 10' $14.99). The wire is stapled to the box's wood frame and also zip tied to the shelving about every 12"-18”.
Step 3: Step 3 - the Shaker Mechanism
The shaker mechanism might be the most challenging part of the project. I tried various alternatives before settling on using an old drill and a bicycle hub which seems to provide just the right amount of vibration to do the job. The drill spins a small elliptical wheel with an offset center hole. (See photo) A small flanged bearing (Photo is bolted to the elliptical wheel which adds addition weight to create vibration. The elliptical wheel is welded to one end of the bicycle axle and the axle then passes through the bike hub which has bearings at each end. The hub is welded to the base plate so that the axle spins and the hub holds it in place.(See photo) The shaker would work by attaching the elliptical wheel directly to the drill but I was concerned it might wear out the drill bearings prematurely. By using the bicycle hub, the greatest pressures from the spinning elliptical wheels is placed on the bicycle bearings (which are easily replaceable), not the drill bearings. The drill is bolted to a steel plate and the plate is mounted on the side of the shaker box frame. (See photo)
The drill is wired through a dimmer switch ($9.99 Amazon) which controls the drill speed and, in turn, the amount of vibration in the shaker box. (See photo) The trigger on the drill is held in the “wide open” position with a zip tie. Some drills come with a lock to keep the trigger engaged, but the old discarded drill I used did not have a locking mechanism.
Step 4: Step 4 - the Results
The sifter creates nice sandy loam, which can be seen in the video, and also stones which we use to make boarders and garden paths. (See photo)