How can I calibrate my Ohaus cent-o-gram model 311 balance scale?

In summary, the user has a classroom full of Ohaus cent-o-gram model 311, most of which work fine but a few cannot be calibrated to 0. The user has tried using the calibration screw and placing coins under the tray, but is looking for a way to do a course adjustment. Another user suggests checking the field service manual and the missing shot underneath the pan. The original user realizes that each balance has a unique identifier and mixing up the parts can cause calibration issues. They have now successfully calibrated most of the balances but one still remains uncalibrated due to mismatched parts. It is suggested to mark the odd balance for future reference. There is also a reference to the Discworld goddess Anoia, known for
  • #1
tony873004
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I have a classroom full of Ohaus cent-o-gram model 311. Most work fine, but a few I can't calibrate to 0. I've used the calibration screw, but even maxed out it isn't enough. I could always place a couple of pennies under the tray, but there's got to be some way to do a course adjustment. Anyone?
 
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  • #2
I've used these a LOT.
Sounds like the shot is missing from underneath the pan.

See field service manual 3-3 B:
https://www.daigger.com/Portals/0/Literature/1260D_SM_OHAUS.pdf
 
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  • #3
Thanks! I see what's going on now. I assumed they were all identical, and there would be no reason for factory-installed shot to go missing. But they're not identical. I didn't realize that each balance, its mass hanger, and its tray are all stamped with a matching 4-digit number. If you mix up the parts, you can run into trouble calibrating them. Now that I've put them all together by number, they all calibrate except one. Its parts do not have matching numbers. I'll just put some staples and paperclips in with the shot.
 
  • #4
Cool - good catch for others resurrecting old equipment.
May be an idea to renumber or otherwise mark the odd one, for future generations, too.
 
  • #5
I expect that somewhere you have another uncalibrated balamce, also made from non-matching parts.

Possibly this is a job for the Discworld minor goddess Anoia, responsible for Things that Stick in Drawers, Lost Cutlery, etc, ... and considering moving on to become Goddess of Hopeless Causes. :biggrin:
http://en.wikipedia.org/wiki/Discworld_gods#Anoia
 

Related to How can I calibrate my Ohaus cent-o-gram model 311 balance scale?

What is the purpose of calibrating a balance scale?

Calibrating a balance scale ensures that it is accurate and precise in its measurements. This is important for obtaining reliable and valid data in experiments or other scientific applications.

How often should a balance scale be calibrated?

The frequency of calibration depends on the specific scale and its usage. In general, it is recommended to calibrate a balance scale at least once a year, or more frequently if it is used frequently or in a harsh environment.

What are the steps involved in calibrating a balance scale?

The steps may vary slightly depending on the type of scale, but generally involve placing known weights on the scale and adjusting it until it reads the correct weight. This process is repeated with different weights to ensure accuracy. It is also important to clean and level the scale before calibration.

What should be done if a balance scale cannot be calibrated?

If a balance scale cannot be calibrated, it may be malfunctioning and should be inspected or repaired by a professional. In some cases, the scale may need to be replaced.

Are there any specific precautions to take when calibrating a balance scale?

Yes, it is important to handle the weights carefully and ensure they are clean and free of debris. It is also important to follow the manufacturer's instructions and use the appropriate weights for the scale. Additionally, the scale should be calibrated in a stable environment, free from vibrations or other disruptions.

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