I risked $14 on this bargain scale

Nick Zentena

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Doesn't come with the calibration weight? That's the main issued I'd have with it.
 

David A. Goldfarb

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The really cheap ones can have linearity problems. See if you can test it with some standard weights--1g, 5g, 100g, 200g, say--and see if they are all correct.
 

kman627

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I use to be a Scale technician and I've never seen such a model or brand. That of course doesn't mean it won't work. I'd also look at investing in a
150g cal weight. You should be able to figure out the Cal procedure pretty easy.
 

Butler

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Calibration weights

Hi, This may be obvious but you can save some cash obtaining calibration weights by using water. 1 milliliter of water equals 1 gram. Zero the scale with an empty container, add a known volume of water. If you want to get compulsive you can use distilled water.
 

rwyoung

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I think that trick works at 4C and "sealevel" to get 1ml (1cm^3) = 1g. And even then, from memory, it is more like 0.99997g/cm^3...

But I believe it will be linear so you can test the linearity of your scale and since your scale is 0.05g resolution you probably wouldn't see the difference anyway!
 

dsullivan

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A less messy choice would be coins, they're a known weight and are easy to come by. Neither may be quite accurate enough for the scale shown though.

David.
 
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jstraw

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I'm down the hall from the temporary quarters of the university chemistry dept. I think I'll just bring it there and use their calibration weights. But the day I come home from work and find it delivered, I'll probably try the water trick.
 

Jon King

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dsullivan said:
A less messy choice would be coins, they're a known weight and are easy to come by. Neither may be quite accurate enough for the scale shown though.

David.
Click to expand...

U.S. Nickels weigh 5.0g by design- use new ones though, but I'd check the linearity of the low values with the chemistry dept. weights.
 

craigclu

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I had a good scale fail on me and was quoted $400 to repair so I took a chance on a used little 200g Acculab from eBay. I miss the capacity of a larger scale as I prefer to measure negatively from the supply vessel but am functioning fine with the little one. I weighed some items on a calibrated high-end scale (Mettler 2000, 0.01g) at work and found that the little scale agreed so I trust it. I used that scale to prepare a 100g calibration weight from a film can trickled to the correct weight with sand.

Another thing to consider is that low/moderate (all, really) priced load cells can be more accurate in the middle of their rated range, or at least, away from their limits. If you place an approximately 50g weight on the scale and tare it, the subsequent measure of small amounts will be more likely to be accurate. I still use a powder/reloader balance scale for phenidone and other very small amounts so the 0.1g ability of the Acculab serves me well enough for most other things.
 

dancqu

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jstraw said:
I'll probably try the water trick.
Click to expand...

Only so accurate as is the calibration of
your vessel. Works with other fluids as well
and a great way to determine the specific
gravity of all your solutions. Dan
 

fhovie

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I sell scales - industrial scales - from weighing pharmaceuticals to oil derricks. Before that I sold Automotive test equipment. No matter what there is, someone will make it cheap. It is not that cheap products are available that amuses me. It is how people buy things. I have bought cheap things. They last long enough for me to pitch them and get something good. Maybe used .... but good. So what does a photographer spend on a lens? A camera body? A light meter? Strobes? Tripods? Then there is the discussion of a scale or a tray for a few dollars. Not that I am not also guilty, but it is kind of silly to have $10,000 in lenses, tripods bodies and strobes and then go to soup those negs in mystery mix where no two batches are quite the same. I am not saying it is silly to save money but it is all a system and sometimes $10,000 worth of image making equipment and hours of priceless time are at the mercy of an unknown cheap component. I guess even this comment could be in that category as well - so I am laughing at myself now.
 
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jstraw

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The scale arrived. I put a nickel on it. "5.00"

Not 4.96...not 5.01, 5.00

Good sign. I'll let you know how it tests out on Monday.
 

dancqu

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craigclu said:
I still use a powder/reloader balance scale for phenidone
and other very small amounts so the 0.1g ability of the
Acculab serves me well enough for most other things.
Click to expand...

Just how low do you go with that beam balance?
I've an Acculab 200 gram 0.01 and am very pleased
to have. With it I draw the line at 1.00 gram minimum
so the interest in a rare use of a powder balance. Dan
 

craigclu

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dancqu said:
Just how low do you go with that beam balance?
I've an Acculab 200 gram 0.01 and am very pleased
to have. With it I draw the line at 1.00 gram minimum
so the interest in a rare use of a powder balance. Dan
Click to expand...


My Acculab 200 is a version that reads to 0.1g. My setup has both scales handy at hand to use and I've just gotten into the habit of using the powder scale on the smaller measures. My recipes are on spreadsheets and I simply have the conversions done and in front of me when I go to mix things. I've attached a typical recipe with a few small-weight components. I feel better with my equipment to measure for instance 23.1 grains of glycin than 1.5g on the inexpensive digital.

Our metrologist suggests to us that if we are adding key, trace components that even on some multi-thousand $$ units at our lab, we should add a 50g weight to the tare to get away from the extreme end of the load cell range. It may be interesting for you to try your scale at various points of its range in this manner and see if the small weight remains constant and whether there is load cell "memory" when going from one end of its range and up and back through its range. If it seems consistent, I suppose there is little need to bother with the supplemented tare weight routine for darkroom duty for you.

You should see what we go through to weigh certain things with vacuum chambered units kept in +/- 1°, humidity-controlled clean rooms and other units that use helium to displace a vacuum chamber to measure porosity, etc of particles. I'm still in a sort of wonder at the sensitivity of some of these devices. If I had a scale like yours with 0.01 sensitivity, I would use it just as you do and perhaps see if it's any more consistent away from its load cell limits as mentioned. Another thought is that using a consistent technique for batch to batch behavior is likely more important than splitting hairs on scales? I especially use scale care when doing small batches of a developer that I may simply want a one trial look at as I have way too many liter bottles sitting here with one film test of chemical consumed
and didn't have a reason to get back to the project. I'm more apt to rely on the balance in that case.
 

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