jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
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Post by jamesp on Mar 9, 2019 10:31:50 GMT -5
Hand held vibration analyzers used to cost over $1000 a couple of decades ago. Well our friends in China are selling one for $104 on EBAY. A photo of the end of the hopper and a hand drawn rendition of hopper with (rough) estimated vibration displacement profile graph. Note strange pivot point. Probably close to center to get material rotation. Note displacement increases the higher up the hopper. This hopper is homemade and about 2 inches lower than the factory hopper below the .7mm zone. The homemade will not bruise/frost glass, the taller factory hopper would bruise/frost glass every load. Have ordered this hand held vibration tester to accurately measure these displacement measurements. Up and down, she to side(in drawing) and if present side to side in the 3rd dimension. It will take accurate displacement measurements at 3000 vibrations per second from 0 to 2mm. 0 to 2mm should cover the range for most rock vibes. The estimations in drawing seem to be bigger numbers than actual. This analyzer may be a godsend for adjustable vibes for stones like obsidian. Most industrial vibes have these analyzers built in to tell you how to make adjustments.
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Post by gmitch067 on Mar 9, 2019 13:03:59 GMT -5
Interesting find jamespConsidering the commercial version of the Vibrasonic or the Mini-Sonic which have speed control... Does the speed adjustment vary the displacement results?
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
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Post by jamesp on Mar 10, 2019 10:44:56 GMT -5
Interesting find jamespConsidering the commercial version of the Vibrasonic or the Mini-Sonic which have speed control... Does the speed adjustment vary the displacement results? First thing to consider, vibration components are complicated. Being able to measure them is a big help. Easy to measure the speed of a rotary, not so easy to measure vibration components on a vibe. The Vibrasonic only has a counterweight adjustment Mitch. The motor is always running at 3450 RPM. The counterweight shaft always at about 3000 RPM. By adjusting the counterweight you can reduce/increase the displacement. The problem - at low counterweight off-balance settings the displacement was reduced to acceptable displacement levels. But it did not have enough off-balance power to shake the hopper with thick slurry. Not to mention the geometry problem with the tall factory hopper. The Mini Sonic may have a frequency(speed) control - not sure. Or it may have constant frequency and have a power control - not sure. The Lot-O has no 'easy' adjustments except moving the dowel which would be considered a geometry adjustment. displacement result ? - not sure. The GY-Rock has (I believe) is a 2 speed. I believe you change the pulley sheave to get 2 different speeds. displacement result ? - not sure. So there is a plethora of variables that can change displacement. My experience is with the Vibrasonic. The displacement 'zone' seems the smallest where the pivot point is shown in this drawing for this given 8 pound hopper at a given counterweight adjustment: If a taller heavier hopper was mounted on the Vibrasonic the pivot point would certainly change because the system has springs and the springs react differently to the added weight and different geometry of the new hopper. So the need for a vibration analyzer if experimenting with displacement(and acceleration, velocity, frequency). ALL OF OUR VIBES HAVE SPRINGS making changes unpredictable. I would guess the Lot-O has a similar pivot point location. I can tell you the acceptable displacement for softer materials if the vibration analyzer works as anticipated since I have Lot-O and a modified Vibrasonic that does well with soft materials to try it out on.
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