|Monthly Tech-Tip |
While sieve shakers are common for processing powders, this page is about processing slurries. To slurry up a clay body, glaze or engobe it is customary to sieve it. But that can be time-consuming, especially for finer mesh sieves. This inexpensive vibrating shaker changes that, doing in seconds what would either be very difficult or impossible by hand. We got the initial idea for this from shower-shelf.com (see links at bottom of this page).
To make the shaker described on this page access to metal fabrication skills and equipment and a 3D printer and 3D design skills are required. But since this entire website promotes independence and understanding of materials, process and equipment in the ceramic process, whether as a potter or manufacturer, we consider these resources to be essential. Even for serious hobbyists.
We made this from an inexpensive 30-watt vibration motor from Amazon (it is of excellent quality). The motor has movable weights on both ends of the shaft, rotating them enables fine control over the amount of vibration (as shipped it vibrated far too much).
We used a 3-inch length of 8 1/4 inch inside-diameter steel pipe (for use on pipelines). The motor mounts to a 1/4 inch plate welded to an upright section of 1-inch angle iron. The flange of a standard Tyler sieve measures 8" so we 3D-printed a three-piece collar that fit tightly over the end of the pipe, it holds the sieve firmly. The assembly fits into notches on a standard 5-gallon pail, by virtue of four bolts threaded into holes in the pipe.
When the vibration is right for us the bucket moves around on the floor a little when empty. If the slurry is made from 200 mesh materials, and the sieve is coarser than that and has plenty of water, it should pour through at speed. If the slurry is a clay having impurity particles and sand, it will go through quickly at first but then slow down as the oversize collects. To deal with this, pour in batches, allow the oversize to coagulate into islands, then stop and remove them before continuing. Using this method we are able to sieve MNP, for example, at 140 mesh very quickly, 2-5% is oversize.
Deflocculated slurries (bodies, glazes and engobes) are very difficult to sieve because they can be thick and sticky. But vibrating the sieve makes it easy. Flocculated slurries (e.g. engobes) are also much easier this way. A sieve shaker also enables processing slurries having a lower water content than would otherwise be possible.
Being more independent is now cool again. Actually, it is being forced upon us by necessity because of supply chain issues and skyrocketing prices of convenience glazes, bodies, engobes, etc. Independence involves using sieves. True, it is no problem for a potter or lab tech to manually coax a glaze slurry through a small 80# sieve. But real independence is about sieving in volume - clay bodies and casting slips. About making your own porcelains and sieving out agglomerates. The ultimate in independence: Sieving particulates from your own native clay slurries. And doing it at 100, 140 and even 200 mesh. That requires a sieve shaker. This one cost us less than $100 to make. Of course, a Tyler sieve (or similar) is needed, these can be purchased on Ebay or Amazon. And a vibration motor, some metal and hardware and a friend with metal fabrication tools.
This is the smallest one they have and plenty big enough for this purpose. It arrived within a few days after ordering.
The position of the weights on the shaft determines the amount of vibration. The notches in the three plates hold them in place. When adjusting the position of the plates be very careful not to get your hand caught in them when turning the motor on! Experiment with different settings to get as much vibration as your setup will tolerate without shaking the sieve out of the mount. Reinstall the protective caps as soon as possible.
This is a 140 mesh Tyler sieve. It drops into the plastic 3D printed collars and fits tightly. And the collars also need to mount tight on the pipe so everything stays secure during vibration. The collars were printed, upside down, in 110 degree sections. I created the design using Fusion 360 by drawing the cross-section profile and then dimensioning and revolving it. Typically creating these is try-adjust-print-again process to get a good fit. Remember never to wash these printed parts in hot water or they will warp.
Video of ingenious vibrating sieve system used for casting slip at shower-shelf.com
ShowerShelf.com vibratory screen that fits the top of a five-gallon bucket
|By Tony Hansen|
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