Scales that can't make up their mind

[Brian Gaff]

Depends on whether its a strain gauge type or a normal mechanical scale with mechanical linkages to a rotating pot of some kind. I've seen both fail. the rotating pot gets noisy and intermittent due to wear and muck, and the strain gauges can have bonding issues with the part that flexes. You say its LED, normally they are LCD as they need to emit no light at all and the battery lasts longer. I have a talking set myself but I could imagine in a multi person house this could be embarrassing! Brian

[Brian Gaff]

I find a sheet of hardboard under them fixes that. Brian

[Brian Gaff]

Actually a good clean might be enough, but if you can find sewing machine oil it can work wonders when you degrease and get the gunge out. Brian

[Brian Gaff]

Well I'd not go that far, but did you know that on different bits of the earth the gravity can vary and hence no scale is going to be completely accurate?

Salter used to make the Weightwatcher scales, but as most of these things tend to be made in China anyway, the actual make probably does not matter. Brian

[PeterC]

Agreed - if I had the space for a beam balance... Had an electronic scale once, crap, went back to the Krupps mechanical one that was old when I aquired it in the early '90s. Accuracy: unknown; consitency: good.

[PeterC]

Will they accept incremental weights? My electronic ones woudn't, so I couldn't add/subtract items that I wanted to weigh. I was trying to get the load on the front wheel of a bike so that I could use the laden rolling radius - had get the old scales to do it.

[PeterC]

A balance scale will be the same, as the mass of each sides is equally affected - that's where the beam balance is good. When I was young (4 - 8 yo) my parents had a small shop; I found the beam balance of great interest and very easy to use.

[Michael Chare]

No, you would have to start again but the repeat accuracy is very good.

[Bert Coules]

And so is this. A slip of the fingers and the brain.

Thanks to you and everyone else for the further thoughts. My first attempt at a fix wasn't entirely successful: one of the displaced feet didn't stick securely and came loose again as soon as I put any weight on it. I'll have another go.

The feet/sensors strike me as a pretty weak part of the design. Their springing is just four rather flimsy plastic sprues which connect the actual foot to the securing flange.

[PeterC]

Thanks. The Aldidl electronic ones had the gimmick of repeating the previous weight if close enough. Had to trick them into accepting small changes.

I noticed on Salter's site that the 'accuracy' is to 50g - that's the precision (and no, it's not very precise) - there's no mention of accuracy.

[Dave W]

Strain gauges don't have springs. My bathroom scales have feet suspended on flat plastic spirals to allow them to move. They press on the strain gauges underneath that are fixed to the solid glass base.

If it's just one of your feet that's come off, not the gauge underneath, then you're probably just experiencing the scales sometimes pressing on three feet instead of four.

[Bert Coules]

Yes, my scale is the same (minus the glass base). But the flat plastic spirals, whether you call them springs or not, still strike me as a weak area, even though the amount of travel of each foot is restricted, as you say, by the strain gauges located immediately above.

I'm intrigued by the fact that two of the four feet are connected to the PCB by very fine twin wiring. The uppermost part of each foot, the bit that presses against the gauge, appears to be metallic, but unless there's more going on inside the rest of the foot than seems likely, why *two* wires?

Yes, I think you're right. Thanks for the thought.

[Bert Coules]

Unfortunately my refix fix didn't work: even with all four feet now securely in place and correctly bearing on the strain gauges I can't get a stable reading from the scale: it flits about from figure to figure, though always within a range of about half a stone up and down.

So perhaps the problem is electronic? Whether it is or not, I can't see any way of correcting it, sadly.

Thanks to all for the thoughts and suggestions.

[Dave W]

My scale goes blank for about 3 seconds when I step on it, then displays what I suspect is the average during that time. Maybe your software is displaying your fidgeting instantly, not averaging. It would be interesting to put a heavy weight on the scales instead of you standing on them, to see if the reading stays steady.

[Bert Coules]

The fidgeting (nice description) has come on only very recently, which does suggest some kind of fault, but I'll try that, thanks.

[Bert Coules]

An update: I tried heavy objects (well, lighter objects than myself) and discovered that up to around two stone the scales behaved perfectly, displaying an immediate reading with complete stability. Above that, the display fluctuated and never settled on a single figure.

Useful for parcels then, but not for me, unless I go on a fairly drastic diet.

[Fredxx]

That's not my experience. I tend to aim for resolution which does tend to mean a better strain gauge and lower noise electronics.

[tabbypurr]

Beam balance are accurate & last centuries. No electronic scale will do that. Shame that beam balance are also slow to use, expensive & bulky.

NT

[The Natural Philosopher]

the problem is they read diffrently depending on where tou place the weight

I spent 2 days reading the reviews of ALL the scales on Amazon. Not one didn't have someone saying 'acccureacy is shit and depends on where you stand' even after making sure they were on a hard level surface.

[2987fr]

Whatever some competitor says, this one does in fact give very reproducible weights and isnt just faking that because it gives a different weight differing by the right amount if you pick up something small and weigh with that as well.