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peach
Bon Vivant
Posts: 1428
Registered: 14-11-2008
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By 0.1mg, you mean 0.1 milligrams? If so, that's not impossible no.
I do see people purposefully using mg to mean micro, which is u (mu) or, if you're a doctor, mcg - which was introduced to avoid dosing errors due to
handwriting.
The Cahn balances claim a resolution of 0.1ug, three orders of magnitude more.
A Cahn 25
BIPM's 0.1ug balance - They are not going to have built that chamber, and the entire balance within, if they could have got the same results from a
Cahn out on the desk, unlevelled
[Edited on 26-1-2011 by peach]
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S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
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Attached is a picture taken minutes ago of a pair of my "old 0.1 mg. models", and the other balances I've mentioned in this thread. Needless to say, I
did not pay anywhere near new prices; no one else needs to either if they keep their eyes open. Note the location of the decimal point on the
electrobalance; the knob at far left is on the 2 mg. setting. The picture is not good enough to show the pan at A well, or at TARE at all. Edit: I
just can't make a post without editing it...I wrote the above before getting the 800 pixel limit message....I thought that applied to the other
dimension...so now you'll need some magnification to see that the decimal point is to the left of all the 0's...and the printing right above the
readout is: MILLIGRAMS
[Edited on 26-1-2011 by S.C. Wack]
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S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
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While you could buy a nice model 29 today for $1,924.00 + shipping, you could have picked up a working model 25 in Memphis last Wednesday for $71.40. Not as useful as a triple beam, I know, but they can be nifty to have at times.
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unionised
International Hazard
Posts: 5126
Registered: 1-11-2003
Location: UK
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I use a cahn microbalance like that at work. I don't trust it to the 100ng it claims, but it's perfectly capable of weighing your signature to 4
digits.
The BIPM's balance is, of course, a bit more sophisticated but all that chamber is for is to let them use it in a vacuum.
Incidentally, it's not possible to check the balance to the standards normally used because nobody (including the BIPM) can certify a test mass to
that accuracy.
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bob800
Hazard to Others
Posts: 240
Registered: 28-7-2010
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Balance selection
I'm looking to buy a balance with a resolution of 0.01g, and a capacity of 100-200g. So far, I've found a few balances that seem worth it:
1) A $163<a href=http://balance.balances.com/scales/419> Ohaus "Cent-O-Gram"</a>, which is a mechanical balance  . Do you think that this is a good idea, or I should stick with digital balances? I
couldn't tell if weights were included though. Are weights usually included for mechanical balances?
2) A $99 <a href="http://balance.balances.com/scales/1">My Weigh iBalance 201</a>. Has anyone tried this brand of scales before? I've
heard negative things about their pocket scales, but nothing negative so far about this balance. Any opinions?
3) A $184 <a href="http://balance.balances.com/scales/471">Acculab VIC212</a> scale.
What do you think is the best option? Any advice would be greatly appreciated! Thanks!
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redox
Hazard to Others
Posts: 268
Registered: 22-2-2011
Location: The Land of Milk and Honey
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I wish I had one of these scales  . I have been working with this stupid little
incredibly inaccurate balance which just doesn't cut it for work requiring a resolution of 5 grams or less.
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thorazine
Harmless
Posts: 27
Registered: 4-3-2009
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Hi!
I was searching for a scale and found this: http://www.scaninst.com/lang-en/serie-wtb/120-wtb-200.html
But the seller says that it hasn't internal calibration. What that means? I need to calibrate it manually? Thats it?
Thanks!
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Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
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Mood: Chemistry: the subtle science.
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I'm considering buying the digital scale (200g x 0.01g) shown in the link below. Does anyone have any experience with this particular model?
http://cgi.ebay.com/AMPUT-0-01g-x-200g-Digital-Pocket-Scale-...
Or, is it just stupid to buy a cheap scale?
[Edited on 17-6-2011 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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bob800
Hazard to Others
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In the beginning of this thread, peach demonsrated the accuracy of his el cheapo scale:
Quote: Originally posted by peach  | Here is the balance I was checking them against - which showed a <1% error on the £6.99 balance. I did this work so others wouldn't have to spend
so much or could get more fun for their money. I was skeptical that these plastic things could even get close to their claimed resolution; accurately.
Particularly as they've never been calibrated and I've spilt agar and other rubbish on them, and knocked them around. But I have checked it for you.
And they do.
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The scale you linked to may not be as accurate, but you don't have much to lose!
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jock88
National Hazard
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Any thoughts on these contraptions?
http://www.ebay.co.uk/itm/Stanton-CL14-1970s-Vernier-Scienti...
http://www.ebay.co.uk/itm/Stanton-SM12-1960s-Scientific-Labo...
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hyfalcon
International Hazard
Posts: 1003
Registered: 29-3-2012
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I needed repeatability so I got this:
http://www.ebay.com/itm/281333430064?ssPageName=STRK:MEWNX:I...
Does what I need it to do.
Wish I was close enough at a chance for either one of those analytical balances. CHEAP also.
Whatever you do, if you get one of those scales, don't handle the weights with your bare hands. Either one is sensitive enough to weigh your
fingerprints so hands off the weights.
[Edited on 8-6-2014 by hyfalcon]
[Edited on 8-6-2014 by hyfalcon]
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