Damping Scales?

dromia

Active Member
I have an almost as new in box set of Ohaus Model 314 three beam scales.

Sitting atop its red "Doric" column it is a fine piece of elegant, precision engineering that is not longer unfortunately available to us.

However being of the day before damped scales combined with finely ground precision engineered balance pivots when set away it almost perpetual motion. The instructions say that the reading can be accurately eyeballed when the pointer goes the same amount each side of the zero. Personally I would prefer it to be damped so I can see whence the pointer stops in a timely manner.

Anyone have any suggestions on how dampen these in a simple manner that doesn't require drilling threading machining and the like?
 

358156 hp

At large, whereabouts unknown.
I have a similar design Ohaus scale that I use whenever my needs outgrow the capacity of my powder scale. All I do is stop the beam from oscillating with my thumb near the center of its swing, killing its momentum, then I release it. It always settles down quickly to give an accurate reading. I'm betting Ric has a more logical way of dealing with this, considering his background in science.
 
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Ian

Notorious member
I do the thumb trick even with my magnetically-damped scales. I have no idea how the magnetic dampers work without spoiling the accuracy or making the beam travel "notchy".
 

RicinYakima

High Steppes of Eastern Washington
I have no idea how the magnetic dampers work without spoiling the accuracy or making the beam travel "notchy".
As the beam moves through the magnetic field, it generates electricity and the energy to dumped into the base as heat.
 

RicinYakima

High Steppes of Eastern Washington
I'm betting Ric has a more logical way of dealing with this, considering his background in science.
My University Chemistry professor would slap you on the back of the head if you dared to touch one of his balances!!! The sweat and salt from your finger (in the 1960's college labs were not air conditioned so you sweat at 90 degrees and 90 percent humidity) so would corrode and add weight from the oxygen to the beam. You made a matrix in your lab book of the number made by each swing and averaged them.
 

fiver

Well-Known Member
seems to me you could build a stop for the bottom side of the swing.
something that could turn in to stop it and swing out to let it go.
it wouldn't completely stop the movement [which I don't think you'd want to do] but it would confine it to a smaller distance.
 

RicinYakima

High Steppes of Eastern Washington
seems to me you could build a stop for the bottom side of the swing.
something that could turn in to stop it and swing out to let it go.
it wouldn't completely stop the movement [which I don't think you'd want to do] but it would confine it to a smaller distance.
My German Professor, with the big club, said that "any mechanical interference" would cause undue wear on the fulcrum mechanism. I would think a stainless steel leaf spring under the pointer would not hurt anything. But at 70 I am still a "dummkopf" and will never be any better.
 

Pistolero

Well-Known Member
Copper plate passing near a magnet. Usually the magnet is stationary,
copper plate moves with beam. Very effective, and with modern ultra
magnets, should be amazing. Only provides a counter force when moving,
does nothing when stationary, no force at all in any direction.

Bill
 

dromia

Active Member
Thank you for the input, I am going the copper/magnet route as I can easily bend some copper and stick that and the magnet to the beam/frame with two sided tape so should be just within my capabilities.

What are modern ultra magnets?
 
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Ian

Notorious member
Neodymium magnets are often used on the tips of oil drain plugs to collect ferrous debris. Lots of field for little size.
 

RicinYakima

High Steppes of Eastern Washington
You realize you will have to add an equal amount of weight on the other side of the fulcrum?
 

fiver

Well-Known Member
would it be equal or enough to off-set.
it seems that if he added weight out on the beam and the tipping point wasn't in the middle he would need more on the short side.
 

dromia

Active Member
Yes realise I will need to balance any weight I add at the front, the scales have a couple of nuts on a threaded rod on the rear of the beam so some adjustment there. I am minded to go with aluminium rather than the copper so that should reduce the weight as well.
 

Ian

Notorious member
There's something in inductance, I think it's "Q" factor if memory serves, which may foil your intent with aluminum. Recovering audiophile here, the Q factor matters with voice coils.
 

dromia

Active Member
Evidently aluminium works. Allan Edwards of Target Master fame, and a master tuner of balance beam scales just sent me this little video to prove the effectiveness of aluminium.

Uses Rare Earth magnets too.