A scale

[Koeng]

So far I have been using a 10 dollar scale off of amazon, and I want something better because it is hard to make exact measurements for antibotics when the amount i need it 0.01 grams and it counts to 0.00. Anyone got recommendations for a new scale? Or should  I keep surfing ebay?

Since I don't want to "spam" I also wanted to ask if anyone knows of any good spectrometers.

-Koeng

[Simon Quellen Field]

Put a small mirror on your scale. Tare the scale to read zero.

Place your white powder on the mirror, and add more until it reads 0.05.

Using your razor blade, divide the pile of powder into 10 equal portions (which we will call lines).

Use one portion, and return the rest to its container.

You have now just increased the accuracy of your scale by close to 10-fold.

Here is a scale that handles 0.1 grams for $5.69.

For twenty one cents more, you get 0.01 gram accuracy.

For $17.00, you can get 0.001 gram accuracy.

I have a number of electronic milligram scales, and an Ohaus dial-o-gram beam balance, and they all agree with one another to the milligram, so I can recommend any of them. They also come with calibration weights.

But you are going to find it quite difficult to beat the $17 price from AliExpress. If you want to wait, I just ordered that $17 one (hey, it's only $17!), and I will test it against my set of calibrated weights and report back to the group.

For those who want even better accuracy, build a simple balance.

Weigh 100 meters of fine enameled copper wire, and calculate the number of centimeters per milligram. It is not hard to get accuracy down to a tenth of a milligram or less by cutting the wire using a millimeter ruler.

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-Koeng

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[John Griessen]

On 01/26/2013 02:43 PM, Simon Quellen Field wrote:
> I just ordered that $17 one (hey, it's only $17!), and I will test it against my set of calibrated weights and report back to the
> group.

Will be interested to hear.

Some day the lack of tariffs for "things from China" might stop.
If we slide far enough... but then it might not, if they own enough of our
loans and dirt already.

[Eugen Leitl]

On Sat, Jan 26, 2013 at 12:14:13PM -0800, Koeng wrote:
> So far I have been using a 10 dollar scale off of amazon, and I want
> something better because it is hard to make exact measurements for
> antibotics when the amount i need it 0.01 grams and it counts to 0.00.

Weigh more (e.g. 100 mg) and use dilution and measure volumes
from a stock solution, assuming it's storable.

> Anyone got recommendations for a new scale? Or should I keep surfing ebay?

We've just ordered http://www.amazon.de/gp/product/B003KMX9FS/
because the reviews are good.

[Eugen Leitl]

On Sat, Jan 26, 2013 at 12:43:15PM -0800, Simon Quellen Field wrote:
> Put a small mirror on your scale. Tare the scale to read zero.

Or buy a volumetric flask, a graduated pipet (both an amazon) and a Peleus ball.
With a sequence of dilution steps you can even dispense individual
molecules (with some degree of uncertainty) if that's what you
need.

https://en.wikipedia.org/wiki/Homeopathic_dilutions

> Place your white powder on the mirror, and add more until it reads 0.05.
> Using your razor blade, divide the pile of powder into 10 equal portions
> (which we will call lines).
> Use one portion, and return the rest to its container.
>
> You have now just increased the accuracy of your scale by close to 10-fold.
>
> Here is a scale that handles 0.1

> grams<http://www.aliexpress.com/item/0-01g-0-1g-200g-300g-500g-0-01gx500g-Balance-Pocket-LCD-Jewelry-Digital-Weight-Scales/640581049.html>for

> $5.69.
> For twenty one cents more, you get 0.01 gram

> accuracy<http://www.aliexpress.com/item/free-shipping-Mini-0-01g-100g-Gram-Electronic-Digital-Balance-Weight-Pocket-Scale-factory-price/642109016.html>
> .

> For $17.00, you can get 0.001 gram

> accuracy<http://www.aliexpress.com/item/5pcs-0-001-20g-Digital-Weighing-Scale-Gem-Scale-Jewelry-Diamond-Scale-Pocket-scale-Jewelry-Scale/485898931.html>
> .

[Nathan McCorkle]

On Jan 27, 2013 2:44 AM, "Eugen Leitl" <eu...@leitl.org> wrote:
>
> On Sat, Jan 26, 2013 at 12:43:15PM -0800, Simon Quellen Field wrote:
> > Put a small mirror on your scale. Tare the scale to read zero.
>
> Or buy a volumetric flask, a graduated pipet (both an amazon) and a Peleus ball.
> With a sequence of dilution steps you can even dispense individual
> molecules (with some degree of uncertainty) if that's what you
> need.
>
> https://en.wikipedia.org/wiki/Homeopathic_dilutions

I think you meant
http://en.wikipedia.org/wiki/Serial_dilution

[Eugen Leitl]

On Sun, Jan 27, 2013 at 01:17:28PM -0800, Nathan McCorkle wrote:

> > With a sequence of dilution steps you can even dispense individual
> > molecules (with some degree of uncertainty) if that's what you
> > need.
> >
> > https://en.wikipedia.org/wiki/Homeopathic_dilutions
>
> I think you meant
> http://en.wikipedia.org/wiki/Serial_dilution

I indeed did meant that, but above article is far more illustrative.

[Simon Quellen Field]

That model is basically the same as the $17 model from AliExpress.

Probably made in the same factory.

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[Simon Quellen Field]

I promised to send the group the results of my tests of the $17 milligram scale from AliExpress.

It seems to be everything it claims to be.

It is accurate to the milligram (as you can see in the attached photo of it weighing a 10 gram calibration weight).

They even include the calibration weight.

You will need to close the cover to keep air currents from changing the reading -- it is that sensitive.

My normal breathing puts a few milligrams of extra force on the weighing pan.

The whole thing is about 4 inches on a side, and less than an inch high. It does fit in my pocket.

Also included are a pouch to store it in (don't bother -- just keep the padded box it came in), tweezers,

a weighing pan, and the calibration weight.

The original post asked for something more sensitive than 0.01 grams. This is ten times more sensitive.

But if you need more than that, weigh out a milligram of powder, and then cut it into 10 lines using a razor blade on a mirror, like in the movies. Or dissolve the milligram of powder in 10 cc's of water and pull off 0.1 cc with a small syringe.

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[John Griessen]

On 02/14/2013 01:51 PM, Simon Quellen Field wrote:
>
> You will need to close the cover to keep air currents from changing the reading -- it is that sensitive.
> My normal breathing puts a few milligrams of extra force on the weighing pan.
>

Does it read zero to 0.000 after reading 10.000, and how long to stabilize?

And if you pick up the cal weight with some oil purposely put on your fingers,
how much do your fingerprints weigh?

Sounds quite handy compared to an old Mettler H80 0.001 to 168 gram balance scale...they're huge.

[Simon Quellen Field]

It takes 5 seconds to stabilize after being turned on.

After that, the scale is stable pretty much as soon as I close the lid to keep drafts out.

It goes to 0.000 when I remove the 10 gram weight, and back to 10.000 when I replace it.

To give people an idea of how small a milligram really is, I put 25 grains of salt on the weighing pan, and (as you can see in the photo) the reading is a nice stable 5 milligrams. The salt grains are thus 200 micrograms on average. As you can see in the photo, they differ quite a bit in size, so dissolving them in water and measuring out a tenth of a milliliter with a syringe would work better than dividing into ten piles or lines in this case. But for something finer, like confectioner's sugar or corn starch, dividing in lines would get you easily to the 200 microgram range, with an error of perhaps 20 micrograms. Just don't sneeze.

My fingerprints don't weigh a milligram. But I rubbed my nose and transferred nine fingerprints to my business card one at a time until I got to 1 milligram. So a greasy fingerprint weighs 111 micrograms on average.

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[Dakota Hamill]

Awesome thanks Simon, I think I'll order one then.  Been using a crappy kitchen scale and it's not accurate for what I need.

[Nathan McCorkle]

On Thu, Feb 14, 2013 at 3:14 PM, Dakota Hamill <dko...@gmail.com> wrote:
> Awesome thanks Simon

Indeed!

--
-Nathan

[John Griessen]

On 02/14/2013 03:21 PM, Simon Quellen Field wrote:
> So a greasy fingerprint weighs 111 micrograms on average.

So little!

thanks Simon.

[Dakota Hamill]

I'm going to grab this one, http://www.amazon.com/gp/product/B0012TDNAM/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

which looks exactly the same but is $5 more, but I can get shipping within 5 days vs the 15-26 from the chinese mainland.  How long did yours take to get there Simon?

Are most things that come off Ali Express slow-boated over or do they have warehouses in the US?

[Simon Quellen Field]

Mine got here in about two weeks.

I was in no hurry.

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[Dakota Hamill]

Yeah I wouldn't mind the ship time except I wanted to run a gel tonight...then realized I didn't even have a way to measure 500mg for a gel.  I went to your website to try to make the scale you made which was super cool but, I don't have that stuff hanging around either.  I wanted to think of some in-genius way to counter balance a 5g nickel on a lever/fulcrum thing to find 0.500g but I gave up before I even tried as today was a lazy sunday.  

[Simon Quellen Field]

AliExpress usually defaults to China Post, which then gets delivered by USPS.

Occasionally they use a carrier that becomes DHL by the time it reaches my doorstep.

The DHL option is faster, but I think both go over the Pacific by air.

A cargo ship can get from China to California in a couple weeks, which is usually fine with me.

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[Mega]

I wrote down the link weeks ago, but it doesn't work any more... 

Has anyone found other suppliers? 

http://www.aliexpress.com/item/New-0-001g-30g-Digital-Weighing-Gem-Jewelry-Diamond-Scale-Digital-Pocket-Jewelry-register-Free-shipping/555217458.html  is there evidence this one is possibly ok? 

Or that one? 

http://www.aliexpress.com/item/free-shipping-0-01Gram-200g-Digital-Electronic-Jewelry-Weigh-Precision-pocket-Scale-black/730852696.html

[Mega]

The same thing on Amazone which costs 21$ there has a catch: 

Shipping is free above 25$ :/ 

[Mega]

It may be this http://www.aliexpress.com/item/0-001g-20g-Digital-Jewelry-Gram-Gem-Precision-Scale-Weigh-Mini-Electronic-Pocket/780083393.html

exactly the same? 

[Simon Quellen Field]

Looks the same to me.

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On Sat, Mar 30, 2013 at 3:18 PM, Mega <masters...@gmail.com> wrote:

It may be this http://www.aliexpress.com/item/0-001g-20g-Digital-Jewelry-Gram-Gem-Precision-Scale-Weigh-Mini-Electronic-Pocket/780083393.html

exactly the same? 

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[Dakota Hamill]

I got the one off amazon and it's pretty accurate and tares nicely for
the price, it was $21 or $23 I can't remember, was ordering something
else off amazon so shipping was free. Also, if you have a .edu email,
you can get free amazon prime (amazon student) which is free shipping
on a lot of items. Free for 6 months. Pretty good

[Avery louie]

I got the same scale.  Seems alright.

[Avery louie]

I can measure the calibration weights on the amazon scale and the nice mettler balance in the lab.

--A

[Marc Juul]

On Sat, Mar 30, 2013 at 5:26 PM, Avery louie <inact...@gmail.com> wrote:

I can measure the calibration weights on the amazon scale and the nice mettler balance in the lab.

Seems that someone already did the work for us:

http://www.amazon.com/review/R3FRRGZ42CYNO0/ref=cm_cr_dp_title?ie=UTF8&ASIN=B0012TDNAM&nodeID=284507&store=kitchen

--

Marc Juul