Tips For Using Sensitive Electronic Scales
Some of our forum members have observed issues with the Acculab VIC-123, an 0.001g precision electronic balance made by Sartorius. (The Denver Instrument MXX-123 is very similar.) The two main complaints seem to be sensitivity to drafts, and instability of zero, causing weight read-outs to “drift” over time. We have seen the latter problem in less expensive scales such as the PACT. (Read PACT report).
Forum member Ronemus, who lists his profession as “instrumentation scientist”, offers the following advice:
“It is necessary to isolate the scale from drafts and vibrations. Laboratory scales with this sort of resolution (.001g) generally have a housing around the pan with sliding doors for access and vibration isolators in the feet. Those scales cost thousands of dollars, and some features must be cut to reach a price we’re willing to pay. Unfortunately, the instruction manuals accompanying our scales generally aren’t very good at spelling out the steps necessary to have them operate to our satisfaction.
A small draft (one you can barely feel) can easily shift the reading a few tenths of a grain, so some sort of enclosure is needed. I use a cardboard file box with one end cut out, so 3 sides and the top remain, and that’s good enough for 0.1 gr (6 mg) stability; however, that may not be sufficient for 0.01 gr.
For stable zeros it’s necessary to warm up for at least a few hours (they’re generally left on continuously to avoid drift) and keep the room temperature fairly constant (within a few degrees).
Inexpensive scales are also susceptible to electrical noise, either riding the power line or through the air. Power line noise can be eliminated with a good filtered power strip (I recommend a Tripp-Lite Iso-Bar), not just a surge suppressor. Cordless and cell phones, fluorescent lights, wireless computer networks, baby monitors, etc. can cause problems at short range, so they should be kept away from the scale as much as possible.”
We have also observed that these scales MUST be properly leveled. They just won’t work right if they are tilted even a litte bit. This editor recently worked with an Acculab VIC-123. Its owner was complaining that it would drift and the read-out was constantly flickering. Well the scale was mounted on a plastic folding table with a top that was warped and bowed in the middle. It was virtually impossible to level the scale properly. The scale was also directly under a large ventilation fan. Once we transfered the scale to a bench with a solid flat surface, leveled the scale front to rear AND side to side, and ensured the scale was isolated from air currents, the scale worked perfectly.
I have a Vic-123 myself. I do notice some of the issues you mentioned, but overall I think the unit is unbeatable for the street price. Some people breath like a cow. Control your breathing is important.
With all these caveats, it’s a lot simpler, cheaper and faster to use a simple balance beam! I have used all the suggestions (except for keeping the room temp constant…with the cost of electricity,it’s too expensive to keep the room at a constant temp and I can’t wait three hrs before everything steadies out) and the electronic scales still drift during dribbling
I have the Denver Instruments scale and found it worked far better after calling their service department and having them advise me how to adjust the sensitivity, which I did and I also have found the scalle must be turned on at least 2 hours before using itbut after doing this, it will hold a zero very well and measure oin 10ths of a grain, which I dribble in by hand; it will recognize the diference in two kernals of Varget.