Cheap weighing scale: mechanical vs. digital
I am looking for a cheap weighing scale to measure chemistry. I am starting out with simple cyanotypes but will probably venture out to other processes in the future. I am trying to choose between this digital scale and this analog one.
The digital seems more convenient and perhaps is accurate enough for my purposes - it seems it can even be calibrated and it reads up to 300 gms.
The analog has the advantage of going down to .01 gms but I am wondering if it'll be accurate (with varying temperatures, say). More importantly, perhaps, is the 10gm limit going to be a hindrace with some processes?
I do have a scale that goes upto 500gm but it is old and I imagine has a margin of error of about +- 10 or 20 gms.
Any advice that would help me choose would be welcome.
I will be very surprised if anyone recommends the digiscale. Analog scales are more work, but you can easily tell if they are correct just by buying a 1 gram weight. Temperature shouldn't have any measurable effect, unless you are planning to mix under very exotic conditions.
You can also use a calibration weight with a digital scale. I find mine (a Toyo 250 pocket scale), easy to use, quick and reliable. I check it periodically with a 100g calibration weight.
Be careful, though, with really cheap digital pocket scales, because they can be non-linear.
Any thoughts on whether some processes will require me to measure much more than 10gms of stuff?
How are pennies etc for calibration weights with the mechanical scale? The digital comes with a 100gm calibration weight, but I am concerned about the non-linearity.
Yes, 10 g is way too small. Today I mixed up a liter of print developer, for instance, and I needed to measure 30 g of sodium sulfite. The digital scale's 300 g capacity is more in the ballpark, and should be enough for most developers, unless you need to mix huge quantities.
For fixers, you may want a bigger scale, but what I do usually is measure in two batches when I need more than 250 g, which is the capacity of my scale.
I think Sandy King has the digital scale you're looking at, and it works for him.
I've never used pennies as calibration weights, but my scale has a "parts counting" function, so I've used the scale to count pennies, and it seems to work for that purpose.
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Originally Posted by David A. Goldfarb
I actually own a couple of the MyWeigh scales, the i2600 that measures up to 2600 grams with reading to 0.1 gram, and the i200, which mesures up to 200 grams with reading to 0.01 gram.
Analog scales like the Ohaus triple beam balance are excellent. I used one for many years before switching to digital balances, and even after I switched ot digital I held on to the analog scale for many years before finally selling it. However, the bottom line for me is that digital scales are much easier to use, and just as accurate, and I would not consider switching back.
Last edited by sanking; 10-06-2006 at 12:15 AM. Click to view previous post history.
I just bought an Ohaus triple beam for $45 on ebay, which is good to .1g. You can pick up an Ohaus Cent-O-Gram scale for a little more, say $55-70 which is good to .01g. Personally, I hate digital devices. I've spent a lot on digital timers only to have them crap out suddenly, usually during something important. Your experiences may be totally different, but for me, these older mechanical scales are fun to use, reliable, last forever, fairly simple to repair if broken, are built solidly, and don't cost an arm and a leg - all things I'm looking for in a tool.
I bet you could get a similar digital scale on Ebay for at most 1/2 that price.
Look for gem scales. They come in various sizes handling 100 grams and up.
Resolutions isn't accuracy. So check the resolution.
When I mix up C-41 developer some of the amounts are very small.
Supposedly coins can be used to check weights.
Click on our coins. Then on circulation currency. Then tech specs.
For Canadian coins that gives weights. I assume a similar source is available for US coins.
One advantage of digital is the ability to use "negative weigh" methods of weighing. Here's a paste from another thread...
When measuring dry chemicals, place the supply container, cover off, onto your scale (assuming digital), then tare. The scale will measure negative values as you remove material. This allows you to tap off your spoon on the receiving vessel and better account for clinging material and also helps to avoid mistakes of over-adding that can occur when trickling directly to the receiving vessel or spooning from the supply. It seems so obvious but when I was first shown this, it created one of those forehead flattening moments for me!
Related... I also reload for firearms target shooting. The inexpensive grain scales used for this easily handle very small quantity measuring. I keep my formulas on spreadsheets, with a side column showing the grain equivalent to grams. One gram = 15.4324 grains so if you need 0.2 grams, my recipe also shows the easily measured grain equivalent of 3.1 grains.
The combination of these scales makes for confident weighing. The digital scale that I use is also a counting scale. I'm amazed at all of the applications for this (non-photo related). I can weigh ten of an item and then the scale will tell me how many of the items I have when adding the balance of quantity to the vessel on the scale. For instance, this past week I was given a large bag of empty .45 ACP brass (about 1500). After running through a vibrator/cleaner, I simply had the scale count out lots of 100 for organizing and bagging.