How to Make an Inexpensive Commercial Grade Vibrating Table at Home

Note from Olde World Molds: This plan for a home-made vibrating table was submitted by a customer of ours who wanted to save spending over $1000 for a commercial vibrating table. He claimed that the table cost him less than $150 to make, filled his needs, and that he made over 6000 square feet of stone with the table. Our company has not duplicated the design of this table, but it would seem by the drawings and design to be workable. We've had a couple of customers confirm that the table worked well for them. Since we have no control over the materials or construction methods used to make the table, Olde World Molds in no way endorses the use, design or guarantees the results achieved when making and using this table. We would appreciate feedback. 

A Simple Vibratory Compaction Table Design and Plans

Issue:
Concrete mixes often need to be vibrated after they are poured into molds to get the particles to level and to get compaction of the particulate in the most efficient manner. Variable speed, variable displacement vibrating tables are available through equipment manufacturers for the casting industry. However, OEM equipment may be too expensive for small shops or for the do-it-yourselfer or business start-up operation.

Best Practice: A simple, inexpensive, and effective vibratory compaction table can be built from materials available at any hardware store. The design is self-leveling so that the concrete maintains uniform thickness. It also can be made to have a relatively large displacement at relatively slow speeds. The frequency suggested for vibratory compaction of concrete is 3000 rpm normally.

The following equipment is necessary to build the compaction table:

A fractional (1/3-1/2) horsepower motor or greater for large-size table (variable speed if possible) with a pulley.
One short (1 to 1 1/2") machine bolt as heavy as possible, but thin enough to mount through a hole drilled in the motor pulley, along with several spare nuts and washers.
Four heavy springs such as those used in steel door closures. The springs should be six to ten inches long with connection loops on each end and be designed for extension rather than compression. If total weight of the table, motor, and expected load will be 40 pounds, the springs should each extend about one-half inch with a load of 10 pounds.
Eight lag wood bolts at least three inches long.
Table top material, preferably with a cleanable surface like Formica or thin steel or aluminum, and a thickness and density great enough to firmly anchor the motor beneath. For commercial applications, steel sheet can be used.

Wood for the frame, 2x4's.

Drill a hole in the motor pulley and mount the machine bolt through it. This gives an eccentric weight to the pulley. Check the eccentric by plugging in the motor while holding it in the hands. The eccentric should cause the motor to shake. Add washers and nuts to increase the eccentric, and resultant shaking if not enough.

Mount the motor on the bottom of the tabletop. The bolt on the pulley must turn freely, clear of obstructions. The center of gravity of the motor and pulley should coincide with the center of the table.

Build a frame around the motor, mounted to the bottom of the tabletop. This will be the inner frame. Remember, there will be two frames, an inner frame and an outer frame. Ideally, the outside of the outer frame should be inside the outer edge of the table. That way, any liquids running off the table will run directly onto the floor rather than onto the frame.

Build the inner frame. This frame will support the unit on the bench or floor. There should be at least 1 inch clearance between the inner and outer frames on the sides to allow room for the lag bolt heads and spring bodies. Clearance on the ends should be at least 1/2 inch.

Mount four lag bolts on the sides toward the bottom of the inside of the outer frame and four more toward the top of the outside of the inner frame. Some experimentation will determine mounting points where the table with the motor mounted to it hangs by the springs from the outside of the outer frame without touching any of the sides.

Hang the inner table on the outer frame with the springs. (See drawing)

Test the table by running the motor. The spring tension should be such that the table hangs with only slight spring extension with no load, and does not bottom out on the outer frame under the maximum load. The table should always be fully suspended by the springs.  This is what allows the vibration and movement.

The whole assembly can be placed on a counter. If properly isolated, no walking of the unit should occur during operation.

Because the table is mounted on springs, it will be somewhat self-leveling. However, it is useful to mount a leveling eye on the tabletop so the tabletop can be kept both level and centered.

Since this description was written, it has been discovered that ball bearing "glides"n be purchased at woodworker supply stores. The glides, mounted under each corner, can be a great aid to prevent tipping.

The displacement can be adjusted by adding eccentric weight to the pulley. If a variable speed motor is being used, the frequency changes with motor speed.

Many kinds of vibrators can be purchased. Some electric and pneumatic vibrators fasten to the bottom of suspended tables to generate vibration for leveling materials. Finding the best frequency, displacement, and direction of vibration are all critical factors. The equipment described in this best practice primarily generates vibration in the plane of the table. Some vibrators generate vibration perpendicular to the plane of the table. It has been found by experience and experimentation that leveling cement works better with vibration in the plane of the table.

Implementation: Before building the vibratory compactor, estimate as closely as possible the size and weight of casting to be compacted. That judgment will inform the size of the table, strength of the springs, and power of the motor.

Benefits: This compaction table can be made inexpensively from used or new hardware materials and is a necessary piece of equipment for compaction of poured concrete castings.

Application Sites: Small Producer stone and tile manufacturing facilities and DIY production scenarios.


Note:
I think that this design will work well as it should duplicate both the side-to-side (horizontal or plane) vibration, as well as the up and down (vertical) vibration. This will give the same type of compacting action that one achieves by the hand method that concentrates the fine particulates (sand) and cement solids to the face of the mold. That is really the goal and purpose of vibrating... to compact the solids and result in a harder and denser concrete surface at the face of the casting. The back of the stone or tile is where you want a certain amount of porosity so the mortar or thinset will have a surface to "grab" during installation. You may also scratch the backs of the stone or tile with a steel comb to offer a better grabbing surface for the adhesive.

Should you need...  molds or moulds, colorant, concrete sealer, stains, or other concrete, cement, or plaster supplies for your handyman or home improvement project, please visit our catalogue website at www.TheMoldStore.com or our shopping cart website at http://www.TheMoldStore.us  to get ideas.  If you are interested in starting a concrete stone and veneer, or concrete and cement paver, brick or tile business, visit our Olde World Stone & Tile Business Opportunity website at www.Oldeworld.com for full details, instructions and various stone making and other concrete product making packages.  We also offer D-I-Y Packages in our catalogue and on our shopping cart websites.

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