Building a vibrating table

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Permalink Reply by Anthony Lange on November 10, 2010 at 3:46pm

Mike, In Beckett's book there is a section on vibrating tables. The amplitude and frequency are key factors in the vibrating process. You might want to check that part of it out befor you go out and knock the hell out of your molds...

Permalink Reply by Anthony Lange on November 10, 2010 at 4:19pm

Follow Up - The Science of Chocolate, Stephen T Beckett pg 135
essentially what he says is tat if the apparent Viscosity is high then you dont need to vibrate that much. Pa.s = 3.5 needs little more than 10hz. The lower the Pa.s the higher the Hz. meaning. the chocolate particles in stationary chocolate are close together and to be the bubbles out you really need to shake it. If the viscosity id high (little yield) then you dont need to shake that much. High HZ do not improve efficiency. so aim for 10HZ with an amplitude of 0.2mm (provided the chocolate is quite viscus and you should be fine, Just donr wack it and expect to be doing all that much.

Permalink Reply by Mike on November 10, 2010 at 5:45pm

I have read that excerpt, but the problem is the motor supplier doesn't cater to the chocolate maker :) They don't give any useful specs (for my uses) on the product sheet online, and having just spoke to tech support, they also don't have any information on amplitude. My first concern, is as you mention--I don't want to get one too strong that will wreak havok on my molds. But, its a cheap motor, and returnable, so I think I will just buy it and see how strong it is.

The guy in tech support did say that the frequency would be that same as the frequency that supplied the power (in this case 60 Hz). The plot in Beckett's book shows the ideal Hz at about 30 (at 0.2 and 0.4 mm amplitude), with diminishing returns above and below that frequency. His plot stops at 50 Hz, so I hope 60 is not much worse for relieving viscosity.

I am still interested in knowing the specs from an actual commercial vibrating table motor if anyone has it.

I will report back if I find any useful information.

Permalink Reply by Anthony Lange on November 10, 2010 at 10:59pm

I see you have Becketts book. Then its easy. Unless I missunderstand: Average motor spec 1400rpm / 60 = 23rps (HZ) .... so a speed control with a range from Full 23 to half will work. that is 11.6 HZ. done!. Amplitude from the plate of the table, resting on the cam, use a thread with two nuts to adjust the amplitude. from 0.2mm to 0.6mm. With you now being able to adjust these two parameters, I would use a washing machine motor (the cheapest way to go) and a cam you can get any CNC laser cutter to cut you a cam. Attach it to the shaft and away you go. Ideally, I would do a shaft with two cams, the width of the table (obviously supported on 4 springs), driven by the motor, with the amplitude setting simply done by adjusting the distance of the cam from the table. Just my mind. So in short, and unless Im missing your point, Id say, dont get hung up on the motor spec, Its the science (HZ & Amplitude) you should be getting right. Any motor will do. T

Permalink Reply by Mike on November 18, 2010 at 11:47am

well, after my initial trial, it seems the 1/200th HP motor is under powered for the job. it doesn't seem to produce any "snap." I need to play with different different cushions and see if I can get more of the energy transferred into the mold (different springs, rubber, foam etc....).

Permalink Reply by Anthony Lange on November 18, 2010 at 2:41pm

Hows this for a vibrating table......... would you believe, It actually works. How, dont ask me.

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Permalink Reply by Mike on November 18, 2010 at 3:03pm

i bet its noisy :) looks like the little massager kicks the top plate around while it vibrates loose underneath. mine is actually set up opposite, with the motor attached to the vibrating plate, suspended (as of now) on dense foam. I think i'm getting too much energy transferred to the base because my foam is too dense. more trials over the next few days....

Permalink Reply by Anthony Lange on November 18, 2010 at 3:35pm

actually, Its quite interesting. Its not too noisy but it only hold two molds at a time. One in - One Shaking - One out. Naturally all the science is out the window. but what the hell, Its a toy (till I build a larger one). I'm actually working on a cooling tunnel at the moment. Now, that's a challenge....

Permalink Reply by Dave Elliott on November 18, 2010 at 8:04pm

Oh that's excellent! Is that plexiglass or what material did you use for the plates?

I purchased a round 8-inch dental vibrating table and was wondering what the best approach would be to adapt it for several molds. Your design seems like it will do the trick. Thanks for sharing it!

Permalink Reply by Anthony Lange on November 18, 2010 at 10:22pm

Exactly correct. The thing is really simple. on the top I glued pieces of perspex to the shape of the mold ( a little bigger) so as to hold the mold in place while it vibrates.

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Permalink Reply by Dave Elliott on November 19, 2010 at 11:22am

That's a nice detail to hold the molds. Thanks for the pics, Tony!

Permalink Reply by Anthony Lange on November 28, 2010 at 1:56am

Hi Mike, Just re reading your post where you seem to say that the vibrating table 'doesn't seem to produce any "snap." ' I would say, that I don't believe the table has anything to do with 'snap'. It's the tempering, as I understand it. the purpose of which is to create many, small, densely packed crystals, as opposed to the vibrating table, who's purpose (i think is almost exclusively) is to bring the bubbles introduced into the chocolate during tempering to the surface. (or it might be a little of both) How's that....spoken like a true politician!