Sherline Tongue Weight Scale question

atreis wrote:

RCMAN46 wrote:

atreis wrote:
(It's accurate, but not necessarily precise.)

???????? What a contradictory statement.

Accuracy and precision are not the same thing. Accuracy is how close the reading is to the "true" value, as defined by the central bodies that define and standardize those true values. Precision is how many decimal points the measure can be made at WHILE STILL BEING ACCURATE. (Overly precise is when more digits of precision are provided than can actually be measured accurately.)

As an example, the Cat Scale is certified to be accurate, and the actual value printed out on the sheet will lead you to believe that it's also precise, but it isn't. It might have given you a reading of, say, 4,578 lbs, when it is really only accurate to, say, 4,600 lbs. The rest is the computer taking the reading from the sensors and reporting it, but those sensors can't read accurately at that precision. (They ought to be rounding at whatever point their precision ends.)

The sherline scale basically measures hydraulic pressure 1psi/lb load, and the scales are std pressure gauges with a dial showing weight rather than pressure readout. They just replace PSI with Lbs.

they say the gauge they use has a typical accuracy of about 2% at the center of the scale, and degrades at either end.

Add to that the limited resolution of the small dial,
and then add to the error from the tolerance of the cylinder bore, and any side sticktion.

So, pick a number. 5%??? or so.

I at one time weighed my tongue using the sherline scale then took my trailer to the local highway weigh station. In oregon they leave them open for use when closed. Unhooked the trailer tongue over the scale. Weigh station weight readout is in 50 lb increments. My tongue weight is around 1400lbs. depending on how much water and other supplies are in the trailer. Sherline and weigh station were within 75lbs of each other.

To me that says the sherline is good enough for my intended purpose. Give me a good idea of what my tongue weight is.


Sherline quotes

" The supplied gauge was chosen as the most cost effective solution to providing a result that is sufficiently accurate for trailer weighing purposes. (The Sherline scale is not intended to be used for trade; i.e., items priced by weight.)"