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Author: Subject: Digital Pocket Scales Don't Last?
hodges
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[*] posted on 6-8-2009 at 13:37
Digital Pocket Scales Don't Last?


I'm on my 3rd one.

I bought my first in 2003. Used it a couple of years. Then one day I volunteered to help a friend "smoke out" some moles he was having a problem with in his yard. I brought chemicals and a scale, since I didn't want to mix anything up ahead of time. When I got there the scale was broken - always read "EEE.E". I assumed maybe that could have been because I just threw it in a bag for transport. Or it could have been because I stored it in the same cabinet as my reagents, which means it often had a coat of NH4Cl on it.

I bought another scale. This one I was very careful with. I made sure to never weigh anything beyond its capacity, to treat it gently, and I stored it away from my chemicals. Since I have not done too much chemistry the past couple years, it has not gotten too much use. Maybe once a month at most. So last weekend I tried to weigh something and the weight looked suspiciously low. So I weighed a nickel. Sure enough, the nickel registered 2.7 grams (it should be 5.0 grams). I assumed maybe the batteries were dead, but they checked out fine. I removed the batteries for a while and put them back in. No effect. Everything it weighed came out just over half the actual weight.

So now I'm on my 3rd scale. Not that they are very expensive or anything anymore. I think I paid over $50 for my first scale; the one I just bought is under $20 even with shipping. But it was kind of disconcerting because I thought I took good care (at least of the 2nd one). I'm sure I didn't even get 100 uses out of it.

Has anyone else had this problem?

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[*] posted on 6-8-2009 at 14:14


I have had some really good luck with a cheep 12$ pocket scale from Harbor Freight. It registers .1 grams and can take some abuse as long you make sure you protect it when weighting any solvents. The 10$ model did just like you said after a few days reading EEE.E but the smaller sleaker looking 12$ one recalibrates everytime it is moved. I personaly think thats the key to one that will last a bit. If it shows error because its not ballanced correctly to start with or something then it will kill the scale in no time.




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[*] posted on 7-8-2009 at 12:14


I offer a low tech solution: :D



scales.jpg - 51kB




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[*] posted on 7-8-2009 at 12:21


I buy scales cheap usually about $12 they work fine. EEE.E means overload. If you exceed the scales capacity that's what it will register I assume if you greatly exceed it's capacity it breaks and permanently displays that.



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[*] posted on 7-8-2009 at 14:10


Quote: Originally posted by Magpie  
I offer a low tech solution: :D



I'm sure that will last a lot longer - but I'm sure it also costs a lot more, and of course it a lot bulkier to store. Probably more accurate too though.

I bought a new scale, this one goes up to 500g, so if it gets accidentally overloaded (which I don't think I did with the 2nd one, but it only goes to 200g so picking it up wrong might have done that). Resolution is 0.1g. I had toyed with the idea of getting one with 0.01g resolution but those only measured to 200g or less, possibly perpetuating the assumed problem with overloading. I've only wished for a smaller resolution than 0.1g when doing energetic compounds.

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[*] posted on 7-8-2009 at 23:46


I can vouch for the mechanical scales. there was another thread on here somewhere debating the pros and cons of mechanical v electrical, have a look through the search engine, im sure you will be able to find it. my ohaus triple beam (similar model to the one in the left of magpies picture) meets all expectations. it wont do so well measuring milligram amounts, but to be honest, i doubt there are many amateur chemists who need to work on such a small scale.

price wise it wasnt a problem, just lurk around on ebay until one pops up, i got mine for £5!!! with p+p for like another 5.

this wasnt unique, as when browsing around later, i came across one that was on £10 with no bids and a few minutes to go, if i hadnt already bought the exact same model i would have snaffled it in an instant!
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[*] posted on 10-8-2009 at 06:26


Digital scales are interesting. A 500 gram 0.01 resolution job can range from $15 to $500+. This is a case where you do get what you pay for in longevity, ruggedness, and accuracy. When I decided to equip my lab, I bought one decent scale (A VMC) for about $200, and several of the small pocket scales that I call "drug" scales, because that seems to be their market target.

I am very careful and gentle with the VMC. With the pocket scales, I abuse them a bit more. But they are all shock-sensitive, especially when you are dealing with a milligram scale. The greater the resolution, the more shock sensitive they are. Ultimately, the cheapies can be considered disposable, but their life can be prolonged with care. I'm guessing your failed scale #2 was simply a bad apple, given your care of it. Recalibration often solves problems, because the displayed weight is software derived from the load cell signal.

Anyway, I like the cheapies. They are handy, but you cannot expect great performance or long life from them.
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[*] posted on 10-8-2009 at 17:19


I had two 'cheapies' and they died within a year :(
Even though they were accurate when compared to a professional sartorius scale.




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[*] posted on 10-8-2009 at 17:59


my scale does the EEEE thing whenever it gets dropped. it's east to reset follow the directions on it. I place 7 dixie cups and a tootsie roll pop on it for the exactly 100 grams- seriously I know it sounds stupid but it is 100 grams dead on and my scale allways reads the same as my friends triple beam after the calibration.
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[*] posted on 10-8-2009 at 21:46


I managed to pick up a set of calibration weights pretty reasonable on ebay.Ranges 10mg to 100g for under $50.00.Testing on the high precision scale at work confirmed their nominal stated weight +- 1mg for up to 10g and +-5mg for 10-100g range.Very worthwhile investment,certainly better than a fucking twinky roll.



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[*] posted on 12-8-2009 at 08:48


I wasn't really saying to do the dixie cup thing. I was more suggesting to be creative with what you have around you. There is a good chance he knows someone with a scale so a purchace of weights might be a waste of money for some people.

Also, I should mention that I havent droped my scale in a long time so it might be 6 cups and a tootsie pop my memory sucks.

[Edited on 12-8-2009 by pip]
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[*] posted on 4-11-2009 at 16:11


Go with a MyWeigh Palmscale 5.0 ($45)




It is one of the most popular pocket scales, and it has been around for years (they have a version 6.0 and 7.0 now too, but they still sell more of the v5.0)

I have never had a problem with them, and they are great if you don't require more than 0.1g precision and don't mind a hinged top.

If you are wanting a cheaper alternative, go woth a Proscale 333, this thing is only $12, its about as big as a pack of cigarettes, and its accurate- I have one of them too but I've only had it for about a month, but so far I love it... And it's so cheap you can buy extras in case you break it or spill conc HNO3 on it or whatever...



Hope this helps!
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