Sulaiman
International Hazard
Posts: 3558
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
Do not buy this type of digital scales
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.
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
j_sum1
Administrator
Posts: 6219
Registered: 4-10-2014
Location: Unmoved
Member Is Offline
Mood: Organised
|
|
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
International Hazard
Posts: 1371
Registered: 2-8-2018
Member Is Offline
|
|
Five bucks a piece!!!!!! That's scarily cheap.i suppose at that price you gotta expect hit and miss.
|
|
|
Sulaiman
International Hazard
Posts: 3558
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
just to clarify my statement
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
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
woelen
Super Administrator
Posts: 7976
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
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
National Hazard
Posts: 570
Registered: 27-11-2016
Location: Minnesota
Member Is Offline
Mood: No Mood
|
|
I go with a non-digital scale, as a backup.
[Edited on 5/6/19 by PirateDocBrown]
Phlogiston manufacturer/supplier.
For all your phlogiston needs.
|
|
|
Tsjerk
International Hazard
Posts: 3022
Registered: 20-4-2005
Location: Netherlands
Member Is Offline
Mood: Mood
|
|
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
Administrator
Posts: 6219
Registered: 4-10-2014
Location: Unmoved
Member Is Offline
Mood: Organised
|
|
PirateDocBrown, this looks like it uses antigravity. Rather cool!
|
|
|
PirateDocBrown
National Hazard
Posts: 570
Registered: 27-11-2016
Location: Minnesota
Member Is Offline
Mood: No Mood
|
|
I know, right? Seriously, getting this dang BBS to post the photo right side up was beyond me.
Phlogiston manufacturer/supplier.
For all your phlogiston needs.
|
|
|
DrP
National Hazard
Posts: 625
Registered: 28-9-2005
Member Is Offline
Mood: exothermic
|
|
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.
\"It\'s a man\'s obligation to stick his boneration in a women\'s separation; this sort of penetration will increase the population of the younger
generation\" - Eric Cartman
|
|
|
Keras
National Hazard
Posts: 768
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
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
National Hazard
Posts: 645
Registered: 7-8-2003
Location: Northern kingdom
Member Is Offline
Mood: Very Jolly
|
|
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
Exact science is a figment of imagination.......
|
|
|
Keras
National Hazard
Posts: 768
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
| 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
International Hazard
Posts: 1236
Registered: 29-1-2016
Member Is Offline
Mood: No Mood
|
|
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
National Hazard
Posts: 768
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
| 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
National Hazard
Posts: 561
Registered: 23-11-2014
Member Is Offline
Mood: No Mood
|
|
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
National Hazard
Posts: 645
Registered: 7-8-2003
Location: Northern kingdom
Member Is Offline
Mood: Very Jolly
|
|
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.
Exact science is a figment of imagination.......
|
|
|
Keras
National Hazard
Posts: 768
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
| 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.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
