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Accuracy of scales

I have found that the most precise scales are the totally mechanical one, with moving weight, the Englis therm I think is steelyard, especially if they're checked against a known weight.
 
Valerie Rudwick said:
My scales at home are new. I wear same clothes every week to SW. Regardless of the weight difference a loss should register. It has been the same loss as mine every other week. I don't see how a 4lb liss can carry over to a half pound gain on scales that have over 6 weeks registered the same losses as my digital scales
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If your scales are digital, you could try changing the battery. For all we know, the Slimming World scales may be the errant ones, although I guess others at the meeting might also have had "odd" readings. I also have my scales on a flat, hard surface, rather than anywhere carpeted, which can cause odd things to happen.

I find my weight varies on a day to day basis, depending upon what I've eaten, and other factors, so I do a step-on/step-off routine each morning, then I know what my averages are. It only takes a moment.

Of course that doesn't address your variance between yours and another set of scales.
 
LittleGreyCat said:
Just asking - are you weighed in exactly the same clothes each time?

I weigh myself in the morning just before my shower, wearing what I will wear in the shower.

Not going to attempt that at a pharmacy or surgery!:cool:

I weigh myself every day at the same point in the day - after the morning coffee and the morning evacuation and just before the shower.
This is the best way that I can work out to get consistent results.
As long as this is within a small amount of the surgery scales that is fine by me.
Food and drink can add pounds during the day - just for fun I occasionally weigh myself at night and before my morning routine and the weight is always higher.

I suppose you could always check your scales with objects of a known weight - although the most easily available bulk objects are bags of sugar and flour which I try to avoid.

Cheers

LGC
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1 liter of water weighs 2.204 lbs ADP or 1 kg metric.
 
Valerie Rudwick said:
My scales at home are new. I wear same clothes every week to SW. Regardless of the weight difference a loss should register. It has been the same loss as mine every other week. I don't see how a 4lb liss can carry over to a half pound gain on scales that have over 6 weeks registered the same losses as my digital scales
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Well, either your scales are inaccurate, or the SW ones are. If the others in your group weighing on the SW scales are showing a 5lb variance, then it's likely to be the SW scales. If not, then yours may be underreading. Consistency is usually key for measuring, so my scales stay in the same place on a flat, hardwood floor. Mechanical spring scales can lose tension over time and readings drift, or might just get gunked with dust & need cleaning and lubricating.. even if like Kentoldlady's, they gave me a much better result. Digital scales can also fail, depending on how well they're made but the only weigh to be sure is to test yours against some that you know to be accurate. Or maybe find someone with a pile of free weights and use those to check.
 
Just a suggestion, whatever scales one uses, stick with them and try to disregard other scales. It's a psychological thing. Even if your own scales are wrong, they're consistently wrong. When you have to cope with different scale readings with different results your brain might start to see your success to lose on your scales into failure on other scales.
 
If anyone has more than one scale maybe they could do an experiment for me. Put one scale on top of the other and weigh yourself, what do the scales read? I can't decide if they both would read the full weight or half each, or one would read the full weight and the other zero.
 
Mr_Pot said:
If anyone has more than one scale maybe they could do an experiment for me. Put one scale on top of the other and weigh yourself, what do the scales read? I can't decide if they both would read the full weight or half each, or one would read the full weight and the other zero.
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Is it the same if you stick one on your head and stick your tongue out?
 
Mr_Pot said:
If anyone has more than one scale maybe they could do an experiment for me. Put one scale on top of the other and weigh yourself, what do the scales read? I can't decide if they both would read the full weight or half each, or one would read the full weight and the other zero.
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That's.. not how mass dampers work :p

Scales weigh the mass of whatever's placed on top of them. So the top scale should show your weight, the bottom, your weight + the weight of the top scale. Also why a full shipping container full of scales weighs nothing, but is still charged based on it's mass..
 
first14808 said:
That's.. not how mass dampers work :p

Scales weigh the mass of whatever's placed on top of them. So the top scale should show your weight, the bottom, your weight + the weight of the top scale. Also why a full shipping container full of scales weighs nothing, but is still charged based on it's mass..
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I am not sure what mass dampers have got to do with it. If I am going to be pedantic then the only type of scales that measure mass are the type that use a balance, any others measure weight.
The electronic scales of course work as you say since the scales do not influence each other. It is the type that use a spring I am not so sure about. Standing on a set of scales puts potential energy into the spring, I can't see that the same weight can generate twice the potential energy if there are two springs.
 
Mr_Pot said:
I am not sure what mass dampers have got to do with it. If I am going to be pedantic then the only type of scales that measure mass are the type that use a balance, any others measure weight.
The electronic scales of course work as you say since the scales do not influence each other. It is the type that use a spring I am not so sure about. Standing on a set of scales puts potential energy into the spring, I can't see that the same weight can generate twice the potential energy if there are two springs.
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Youngs Modulus comes into play, and the extension or compression will be linear.
 
Mr_Pot said:
Standing on a set of scales puts potential energy into the spring, I can't see that the same weight can generate twice the potential energy if there are two springs.
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I don't think it does, or not significantly. So figure on common bathroom scales being a top & bottom plate, with a mechanism in between using springs and levers to turn the compression into deflection and move the needle. Normally, bottom plate is sitting on a firm surface and we exert our force downwards. Using 2 sets, same thing applies but there might be a very small upward force from spring resistance. I guess it also depends on exactly how the scales are constructed, ie if you use identical springs in series, their effective rate is half of each spring's rate.
 
first14808 said:
I don't think it does, or not significantly. So figure on common bathroom scales being a top & bottom plate, with a mechanism in between using springs and levers to turn the compression into deflection and move the needle. Normally, bottom plate is sitting on a firm surface and we exert our force downwards. Using 2 sets, same thing applies but there might be a very small upward force from spring resistance. I guess it also depends on exactly how the scales are constructed, ie if you use identical springs in series, their effective rate is half of each spring's rate.
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If it were otherwise than this would be a simple way of losing weight without effort. Smoke and Mirrors? Who would need a magic potion then, or ju-ju juice? Weight Watchers would be out of business in a flash if compounding scales led to a lower indication. Simples. I Speak Your Weight (without the embarrassment)?
 
Or, it could be a diet club variation on the old 'thumb on the scales' trick. If members hit their targets, they may become ex-members.. So adjust scales so they miss! I do like the idea of a personal gravity anomaly for flattering measurements though.
 
first14808 said:
Or, it could be a diet club variation on the old 'thumb on the scales' trick. If members hit their targets, they may become ex-members.. So adjust scales so they miss! I do like the idea of a personal gravity anomaly for flattering measurements though.
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I thought you had to be a large heavenly body to achieve such an anomaly. I am neither large, not heavenly. I just gravitate naturally towards the couch. P.S.Did you mean flattering, not flattening?

I thought thumb on scales was a market trader's speciality.
 
Ah, well.. Like most things in life, bending the laws of physics is easier on the weightier side. So a large mass can bend gravity better than a negative mass*. So a small black hole would do. On the plus side, would get rid of pocket fluff. On the minus, keys, coins and some non-child friendly radiation issues. But negative mass is pyhsically plausible, and potentially necessary. But much like dark matter, the theory is stronger than the observational evidence.

(which is a useful distraction from pondering whether 2 digital scales stacked would give a more accurate reading than 2 mechanical)

*Ok, both should bend reality and gravity equally. But negative mass isn't anti-matter, because that has positive mass.. at least until it annihalates and destroys the scales..
 
Tested my scale , morning i am 42.6kg, afternoon after school is 43.2kg and before bed 44.1kg:arghh: and in the next morning at 42.4kg.Yup scale accuracy is questionable.
 
Gabrielle_Tai said:
Tested my scale , morning i am 42.6kg, afternoon after school is 43.2kg and before bed 44.1kg:arghh: and in the next morning at 42.4kg.Yup scale accuracy is questionable.
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One problem with modern scales is they're maybe too accurate. So the morning is after your night fast & we lose some water mass via perspiration & respiration. Then we eat & drink, taking on more mass and excrete some of it as liquid and solids. So it's normal for weight to fluctuate during the day. And if you're still growing, you'll be gaining some weight from that. So don't worry about it. The more useful thing to watch is the trend over time for any unexpected weight loss or gain.
 
first14808 said:
One problem with modern scales is they're maybe too accurate. So the morning is after your night fast & we lose some water mass via perspiration & respiration. Then we eat & drink, taking on more mass and excrete some of it as liquid and solids. So it's normal for weight to fluctuate during the day. And if you're still growing, you'll be gaining some weight from that. So don't worry about it. The more useful thing to watch is the trend over time for any unexpected weight loss or gain.
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Yes. Just weigh every morning in the same circumstances (after going to the loo and before eating, on the same scales on a stable surface) and keep a moving average of the numbers to look at the trend.
 
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