Sciencemadness Discussion Board - Do not buy this type of digital scales

Do not buy this type of digital scales

Sulaiman - 27-4-2019 at 16:14

2000g x 0.1g digital scales.
A 1.4 kg mass changes weight as I watch it - probably the plastic creeping.
Remove the weight and zero is lost, but the display does slooowly return towards zero.

I suspect that any small plastic bodied scales rated for kilogrammes will have a similar problem.

j_sum1 - 27-4-2019 at 16:27

I have one of these and it seems fine for my use. I have not calibrated it but the readings do stay consistent; which is all that I need.
I did once buy a class set of these for students. The quality was variable. One never worked and we got a refund. A couple show drift over the course of minutes but reset when switched on and off. But they did seem fit for the purpose intended and appropriate to the price paid.

Like anything, yer gets wot yer pays fer. These are a bit hit and miss but, at five bucks apiece, it aint all bad.

draculic acid69 - 27-4-2019 at 17:37

Five bucks a piece!!!!!! That's scarily cheap.i suppose at that price you gotta expect hit and miss.

just to clarify my statement

Sulaiman - 5-5-2019 at 07:23

I only meant to warn against this particular model,
I have an even cheaper 300g x 0.01g scales (also under £5) that I rely upon.
I recalibrate the scales before doing 'accurate' measurements,
but the repeatability seems to be < +/- 0.05g over months.
Once recalibrated I trust these scales to +/- 0.02g
This is the model that I trust

woelen - 6-5-2019 at 01:33

I was lucky to be able to buy a nice somewhat more modern Mettler analytical balance for 70 euros, with auto-calibration option, based on a built-in calibration weight of 100.0000 grams +/- 0.0003 grams. It was so cheap because it was extremely dirty and they discarded it. The dirt, however, only was on the weighing pan, the outside of the case, and the display driver electronics. The entire weighing mechanism, including the calibration weight is completely sealed and non-serviceable. I carefully cleaned the electronics, applied contact spray for the LED-display and cleaned the case and the weighing pan and cabin, but I did not change anything in the sealed weighing mechanism. The disadvantage of this analytical balance is that it only can be used for weights up to a little over 100 grams. Another disadvantage is its slow start-up. It takes quite some time after switching on before it is ready, despite the fact that I have it in standby mode always (it keeps the sealed unit at a constant temperature, lukewarm, 40 C or so, the rest of the electronics goes off in standby mode).

I also had one of these cheap digital scales from eBay (max. 1000 grams, at steps of 0.1 gram). I compared it with my analytical balance. It had some error (IIRC 0.3 grams at 100 grams), but the error was consistent and also linear as far as I could see (at 35 grams it was off by 0.1 grams and at 70 grams it was off by 0.2 grams). This error of 0.3% was acceptable, given the low price of EUR 20 for the device plus shipping. Unfortunately it only survived a few months. After a few months, the tare button became unreliable and in the end it did not work at all anymore. The on-off button also became unreliable. Frequently I could not switch it off anymore and it also did not switch off automatically after some time. It simply drained the battery (a small flat disk). Crap stuff. I discarded it. I will not buy such a cheap thing again. I might buy a good small scale with a similar range from a dutch supplier for 100 euros or so. At the moment I only have my analytical balance.

In the kitchen I also have a small cheap electronic scale, max. 5000 grams, in increments of 1 gram. I did not check its accuracy, we only use it for food stuff. This one also starts having issues with its buttons. Apparently these are the weak part and when used frequently they wear out quickly.

PirateDocBrown - 6-5-2019 at 08:19

I go with a non-digital scale, as a backup.

[Edited on 5/6/19 by PirateDocBrown]

Tsjerk - 6-5-2019 at 15:11

I got one specified to weigh up to 200g at 0.01 precision... for the less than 10 euro price I can't complain but it only weighs up to 100 grams

above 100 it just says it is maxed out haha.

j_sum1 - 6-5-2019 at 15:34

PirateDocBrown, this looks like it uses antigravity. Rather cool!

PirateDocBrown - 6-5-2019 at 16:34

I know, right? Seriously, getting this dang BBS to post the photo right side up was beyond me.

DrP - 7-5-2019 at 01:54

I have a similar problem with creep on my cheapo pocket scales. I get around it by re taring the scale right before each weighing and taking the reading swiftly. They work well enough.

Keras - 7-5-2019 at 03:17

I am planning to buy a precision scale. Since I don’t want any of those cheap crappy Chinese ones, I’m going to pick a KERN EMB 200-2. It’s about € 140, but it seems really sturdy and dependable.

Does anyone ever used a KERN scale?

markx - 7-5-2019 at 03:49

Quote: Originally posted by Keras

I am planning to buy a precision scale. Since I don’t want any of those cheap crappy Chinese ones, I’m going to pick a KERN EMB 200-2. It’s about € 140, but it seems really sturdy and dependable.

Does anyone ever used a KERN scale?

KERN is a a sort of mediocre representative of what could be regarded as a true laboratory scale, but definitely a huge leap forward from chinese noname units. Many laboratories around here use KERN because of the friendly prices and they do work acceptably well. There have been some issues regarding long term stability and floating though. The calibration/verification guys who service the QC labs around my location have told me about this issue.
I use Mettler scales for daily lab tasks and also for dosing in production area and these are really bombproof. Not a single issue with them in ten years regarding precision or keeping it. But the price of course is quite high....

But all in all I consider KERN a fair choice for a reasonable price. I mean even the "el cheapos" given some good fortune tend to be pretty much within acceptable norm, so one can't go terribly wrong with a brand name unit

Keras - 7-5-2019 at 08:12

Quote: Originally posted by markx

KERN is a a sort of mediocre representative of what could be regarded as a true laboratory scale, but definitely a huge leap forward from chinese noname units. Many laboratories around here use KERN because of the friendly prices and they do work acceptably well. There have been some issues regarding long term stability and floating though. The calibration/verification guys who service the QC labs around my location have told me about this issue.

But all in all I consider KERN a fair choice for a reasonable price. I mean even the "el cheapos" given some good fortune tend to be pretty much within acceptable norm, so one can't go terribly wrong with a brand name unit

I don’t expect this scale to be of the finest quality, but that’s not what I need anyway. What I want is to get rid of is the “hit-or-miss” factor you get with those cheap Chinese doodahs. I’ll buy the 200g/0.01g model which seems perfectly fit for my needs, and maybe invest also in a calibrated weight to try and compensate the long term drift.

By the way, I’m also trying not to fall into the trap companies like US Solid set, i.e. selling relatively low priced OEM scales which apparently bear a "made in America" tag, but which on closer look are nothing else but rebranded Chinese crap sold with a huge price bump.

[Edited on 7-5-2019 by Keras]

Herr Haber - 7-5-2019 at 08:23

I got a US Solid (300 grams mg scale) for around 250 Euros and... I love it.
I've tested it with a couple of known weights and the accuracy was excellent.

Keras - 7-5-2019 at 09:33

Quote: Originally posted by Herr Haber

I got a US Solid (300 grams mg scale) for around 250 Euros and... I love it.
I've tested it with a couple of known weights and the accuracy was excellent.

I mean this one. Seems really odd to me to get a 0.001g 300g range scale at such a price. It might be a steal, but I don't believe it. There is another model given for 300/0.001, which is probably the one you own. It has a RS-232 interface, but that doesn't warrant a doubling of the price. The first one must be a (re)branded China model.

[Edited on 7-5-2019 by Keras]

morganbw - 7-5-2019 at 14:55

Get some good calibration weights and then buy cheap scales. Some of the cheap ones are pretty accurate.
Always check the accuracy with the known weights, and then go to town.

markx - 8-5-2019 at 05:44

Everything comes from China nowadays....at least partly, so there is no guaranteed way around the issues. Profitability shall always beat all other virtues, such is the human nature unfortunately.

Keras - 9-5-2019 at 03:04

Quote: Originally posted by markx

Everything comes from China nowadays....at least partly, so there is no guaranteed way around the issues. Profitability shall always beat all other virtues, such is the human nature unfortunately.

Well maybe not everything. I suppose there are still many items produced in the US or Europe. They just cost more.