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On the Lighter Side => Science Experiments => Topic started by: basabeti on 03/09/2009 18:19:49

Title: mechanical weighing machine without spring????
Post by: basabeti on 03/09/2009 18:19:49

can anyone suggest an idea to make an analog(mechanical) weighing machine without a spring or rubber?? please help.... very urgent

Title: mechanical weighing machine without spring????
Post by: RD on 03/09/2009 19:42:55

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http://simple.wikipedia.org/wiki/Weighing_scale

Title: mechanical weighing machine without spring????
Post by: Chemistry4me on 04/09/2009 05:20:34

Or like one of these

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fshanghaiist.com%2Fattachments%2Fshang_markde%2Finstructions3.jpg&hash=edcf8898b4f8dc684cd0d78b7ff35107)

Title: mechanical weighing machine without spring????
Post by: basabeti on 04/09/2009 09:58:18

thats what is the problem... its not so easy.... i cannot compare the weight of the specimen with any known weight as u hav sggested... it should be like i place the weight on the pan and the pointer should show its weight on the scale..without any spring or rubber??? any way?? please come forward

Title: mechanical weighing machine without spring????
Post by: Chemistry4me on 04/09/2009 10:01:40

Can you use water?

Title: mechanical weighing machine without spring????
Post by: RD on 04/09/2009 10:05:00

What about a hydrometer (http://en.wikipedia.org/wiki/Hydrometer) type apparatus where the force against the applied weight is bouyancy (not "spring or rubber" ).

Title: mechanical weighing machine without spring????
Post by: psikeyhackr on 04/09/2009 22:09:42

Put a rope on your weighing lever so that it rotates a drum as it goes down.  Attach strings of varying lengths with weights to the opposite side of the drum so as the drum rotates more and more weights are lifted.  When the sum of the weights equals the weight you are trying to measure it will stop going down.

psik

Title: mechanical weighing machine without spring????
Post by: teragram on 20/09/2009 16:15:38

If the specimens are all of the same material, the displacement in water could be used. The water level in a container would rise when the specimen was (fully) submerged.
A float could be linked to a pointer on a scale.
This would require calibration with a few known specimens, would only work for specimens made from the same substance, requires that the specimens are immune to submersion in water, and would probably not be very accurate, etcetera…

The constraint “no springs or rubber” could allow the use of a load cell, the heart of most modern force sensors, but this requires complicated electronics and would still need to be calibrated, and is after all just a fancier type of spring.

I suspect that the lack of responses to your posting is largely due to the fact that there is no known way of achieving your target, ie. measuring weight (force) by any means other than a balance or a spring.

Many years ago I worked (in a lowly technical position) for Avery Scales. I know they had a team of boffins hidden away somewhere working on this very problem. I understand that they were trying to use the attraction of masses as a weighing system, but this was of course impractical then (1975 ish) and I think remains so.

Title: mechanical weighing machine without spring????
Post by: daveshorts on 15/10/2009 11:30:27

You could also have a heavy (but slightly less dense than water) cylinder floating in water, and attach a string to the top over a pulley, and attach a pan to the other end of the string. The heavier the object the further the float would be lifted. You could then attach a pointer to the pulley.