We’ve had a lot of interest in the Automatic Compost Sifter – Screen post. One visitor of the site, Richard Buxton, posted a comment and sent a picture. I was so impressed I asked him to submit some more details so I could post it up as its own article. So, below we present the “Son of Sid”:
A sieve-box moves backwards and forwards by means of an electric motor. Sifted material falls through a mesh base and a guide chute into a wheelbarrow below. The sieve-box is hinged to allow debris to be tipped out.
Two open boxes; similar to kitchen drawers but without bases, are nested inside one another and arranged so that the inner box may be tipped up on a piano hinge for clearing any material that does not fall through the mesh.
The two nested boxes have four small, in-line castors underneath to allow lateral movement along two rails. These full-length rails are supported on six anti-vibration mounts (Elasto Mount – AT type) that attach through angle brackets to the inside faces of the long-rails of a supporting table-frame.
Movement is provided by a reciprocating saw clamped to a board and firmly anchored across the running rails. The Saw mechanism is connected by means of a push-pull bar fixed to the outer of the two nested boxes with a gate latch and 10mm bolt.
The reciprocating saw has been modified to disable the original power switch and the simple speed control electronics have been removed and adapted to provide a slower rate of reciprocation. A watertight enclosure fixed to the saw mounting board contains the removed speed controller circuit together with an illuminated on/off switch and a speed adjustment knob as operator controls.
The running rails are joined together by cross batons in the manner of railway sleepers so that all moving components and all anti-vibration mounts act in unison. As the reciprocating mechanism moves so does the sieve-box assembly.
The fitted mesh is ½ inch square but a finer mesh of ¼ inch may be dropped in on a sub frame for a finer particle size.
- Overall dimensions of table-frame: Length1340 – Width 560 – Height 950
- Sieve box: Length 610 – Width 455 – Depth 120
- Original speed 300 – 3000 cycles/min. Modified speed 0 – 200 cycles/min.
- Power consumption estimated to be in the order of 100W
You can also see a rudimentary mudguard covering the castor wheel but some
sifted compost is visible on the running rail so I think I will need to fit full length
mudguards instead of these boy-racer ones.
Son of Sid has a very smooth action
The speed controller is subject to variation due to ambient temperature but luckily the purely
accidental selection of components I used (potentiometer and two resistors) allows me to adjust the speed accordingly.
If I load it too heavily I need to turn the wick up a little to get him running properly and as he empties I can turn it down.
The concept idea came from Sid the Sifter and my motivation was nothing more than laziness.
People often say, “Here’s something I made form bits I had lying around.”
True I did use a few lying around bits but I bought most of it – the most sexpensive of course being the saw
which cost £36 ($52)
A huge thanks to Richard for all the great pictures and information!