calibrating scale

[bucketmouth64]

Wondering how you calibrate your fish scale to see how accurate it is. Is it as easy as finding like a 3lb weight and tying a string to it and see if scale is accurate? Does calibrating differ from a mechanical scale vs a digital scale? I ask this because couple weeks ago I caught a 20" largemouth and brand new mechanical scale showed it as 4 1/4 lbs, which I have a hard time believing. It felt heavier.

[Fishinguy40]

To actually calibrate a scale would mean to make some kind of adjustments to it so that it reads accurately. I'm not sure if the average fish scale has the means for a user to actually make adjustments, other than maybe the zero weight.

To verify calibration you can hang a known weight from the scale and verify how accurate it is. To ensure linearity, this should be done at 25% increments across the span of the scale. Example: 0 - 20lb scale, check with a 5lb, 10lb, 15lb and 20lb weight. Just because it reads accurate at 5lbs, doesn't mean it will read accurate at 10 or 15lbs.

[delcecchi]

And the easiest thing to use as a weight is water in a bucket or plastic bag. Each gallon of water at room temperature is 8.3 pounds. So a quart is 2.1 pounds, approximately.

Hang a bucket from the scale, note the reading. Add a quart of water, should go up by 2.1 pounds. repeat until you run out of capacity. Now you should have a graph of weight vrs reading. Adjust so as to take out the bucket by making the line go through zero, unless it is one of those with a "tare" button that zeros it out.

[goblueM]

Wondering how you calibrate your fish scale to see how accurate it is. Is it as easy as finding like a 3lb weight and tying a string to it and see if scale is accurate? Does calibrating differ from a mechanical scale vs a digital scale? I ask this because couple weeks ago I caught a 20" largemouth and brand new mechanical scale showed it as 4 1/4 lbs, which I have a hard time believing. It felt heavier.

4.25 pounds is very possible... bass vary a lot in weight-at-length, and we are notoriously bad judges of weight. I've caught several 20 inch bass that were below 4 pounds, and several that were above 5

calibrating, as mentioned above, would involve changing the scale somehow to read correctly - i think you're looking to just check the accuracy with teh method you mention

[bucketmouth64]

yes, your're right. I want to see how accurate my scales are. Bad choice of wording.

[delcecchi]

One could think of measuring the actual weight vrs indicated wt as a form of calibration.

[BassKnuckles]

More than likely the digital balance will be more accurate. As described above I would test the linearity of each scale. There might be an adjustment available for the digital scale, just contact the mfg. you could ask them what the tolerance is for that balance if needed.

As for the mechanical one you would have to make sure it is completely vertical to get an accurate reading. I've seen a difference depending on what angle you hold the scale at.

Your wording was fine. You could have asked that you wanted to verify your digital and mechanical balance to a known standard and make an adjustment if needed. Wait that is basically what you said. Lol.This is people just being anal, if they actually work in that field they completely understand what you mean.

I never really thought about it but I guess I'm going to bring my hanging scale in and verify it here at work. I have some Class 1 hanging weights that should do the job. Also there might be an adjustment on the mechanical scale, you would just have to ask the mfg or Google to see if anyone has tried to make an adjustment on them or just tear it apart and look for one, it's fun. <---- Geek

Also if you notice that big of a difference between the mechanical and digital it could be that the load cells are shot in the digital one.

[bucketmouth64]

Thanks for the replies guys!