Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Scale question

  1. May 29, 2007 #1

    quasar987

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I bought a 80g x 0.01g scale from ebay and it came with a 50g weight. Now this weight is exactly 50g up to more than 1mg, I suppose? But when I put in on, it read 50.08g. So the scale is off it seems. There are instructions to recalibrate the scale but it seems like the instructions are talking as if I had a 200g scale. It says "To recalibrate, turn on the scale, wait til it read 0.00. Push UCAL. Put a 200g weight on. Wait 3 seconds. Press UCAL. Switch off."

    In any case, I have a 80g scale and it came with a 50g weight. Can I still recalibrate the thing with the 50g weight or I'm gonna screw it up even more? (I tried asking the compagny that made the scale but no response)

    thx :cool:
     
  2. jcsd
  3. May 29, 2007 #2

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    What brand of scale do you have? What does the 50 g standard weight look like? Does it have a shiny silvery appearance or is it painted?
     
  4. May 29, 2007 #3

    quasar987

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Hi chemisttree,

    The weight is like this one: http://www.uptontea.com/shopcart/images/items/AR45-@DFL-200g+weight.gif

    But there is a little defect on it... there is "50 g" carved on the top like in the picture, but the "g" is incomplete, so it resembles more a "q" than a "g". This probably means there is extra weight in the weight thatshould be there. Could that little missing branch in the "g" account for the 0.08±0.01g error?

    The scale brand is Digital Scale E-S Series (it's a pocket scale). Design-wise it is exactly like this one: http://digitalscales.ca/MX50Gemscale.html
     
  5. May 30, 2007 #4

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Until you calibrate the instrument at full scale, you won't get an accurate result. You weighed a 50 g weight and read 50.08 g. You should follow the calibration procedure for the 250 g instrument and substitute the 50 g mass. Tare the instrument with no mass on the pan and read the indicator with the 50 g mass on the pan. It should read 50.00 g unless the linearity is screwed up. Linearity is listed for the model you linked to at +/- 0.01 g. To confirm this you will need some more masses. See here for the method.

    http://www.iescorp.com/linearity.htm

    You might want to confirm that the instrument is on a level surface as well. There is probably no way to adjust the level on this small instrument. You might try small slips of paper if the level is off.
     
  6. May 30, 2007 #5
    If I was you and this happened. I would try to send it back and explain the situation to the seller. Hopefully you could at least exchange it for another one. I doubt that the missing part of the g is responsible for that much of an error but I bet that it could give you at least .01g-.02g maybe .03g but I doubt it would give you much more of an incorrect reading. Is there a hardware store near you with weights?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Scale question
  1. Pauling scale (Replies: 5)

  2. PH scale (Replies: 1)

  3. Question on pH scales (Replies: 6)

Loading...