Musings of a Dinosaur

A Family Doctor in solo private practice; I may be going the way of the dinosaur, but I'm not dead yet.

Tuesday, July 17, 2007

Marble Dinosaur Egg: Extending Your Scale

How to weigh someone over 350 pounds (or the upper limit of your scale; in my extensive research -- looking for this picture -- I found scales that go up to 500 lbs.) on a standard, upright, balance scale:

The trick is to add a counterweight, hanging it from the little piece of metal sticking out at the top of the beam on the top. I find the large rubber bands used by the post office (available from them for free) work well; I use three of them looped end to end.

I use a screwdriver for my counterweight, but anything you can hang freely from the beam will work. Here's how to do the calibration:

Step on the scale yourself and record the reading [assuming you weigh less than your scale's limit, for cryin' out loud!] Then add the counterweight and re-weigh yourself. The difference in the two readings is what your counterweight adds. For example, my approximately 3 oz. screwdriver adds 94 lbs. to my scale's 350 lbs.

When you weigh a patient over 350, begin with the counterweight in place and then add your known differential to the measurement you get.

From the comments on the previous post, the double-scale method (two scales, one foot on each, add the readings) should work mathematically, but it strikes me as cumbersome. Technically, there's no limit using this technique, except that after a certain point, larger people won't physically fit on the scale.

5 Comments:

At Tue Jul 17, 08:36:00 PM, Anonymous difficultpt said...

Genius.

 
At Tue Jul 17, 11:01:00 PM, Anonymous Dr. Val said...

Wow, that's a pretty creative idea. Thanks for the tip!

 
At Wed Jul 18, 07:35:00 PM, Blogger Dr. Smak said...

Clever, clever dinosaur. No wonder you've avoided species annihilation so far!

 
At Thu Jul 19, 11:32:00 AM, Blogger The Tundra PA said...

The last clinic I worked at in Washington State before coming to Alaska had a lovely little set of brass weights that could be hung from a hook just under the bar on the balance scale. There were four of them and they added 50, 100, 150, or 200 pounds to the scale's maximum of 300 pounds. They were such pretty little things. I've never seen them anywhere else. All our scales now are digital, and I've never trusted them as much as a good balance scale.

 
At Fri Jul 20, 10:00:00 PM, Blogger #1 Dinosaur said...

TPA: Very cool. I know I didn't come up with the idea, though by now I don't remember where I heard it. Those pre-calibrated weights are just the ticket!

 

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