Scale Calibration

Ray Daywalker Clarke · Jul 4, 2011

Ok, moving on from the DNA thread, how many FM members have had their scale's Calibrated, and do your scale's weigh, true, underwiegh, or overweigh.

Would be interesting to know what make of scales and how they weigh.

I know many angler's will not be bothered either way, but knowing your scale's weigh correctly, at least you know the true weight of the fish, and not, it weighed about 10lb

steph mckenzie · Jul 4, 2011

I bought some scales a few years ago now, and to be honest with you Roy "sorry i couldn't resist it" i have never ever used them. I bought them with the intentions of using them, i just never got round to buying a weigh sling <mad i know> "what no emoticon". Anyway, the scales are Waymaster Flyweight 30lb x 1oz ...... i'm not sure if they are any good or have a good reputation i bought them off ebay as they were cheap at the time.

I wouldn't know how to get them calibrated anyway.

quickcedo · Jul 4, 2011

The nearest I get to calibrating mine is to weigh a bag of sugar or two.

barbelboi · Jul 4, 2011

Reuben Heaton Flyweight Mk2 Scales – IMO these are pretty much as accurate as you can get for a reasonably priced set of scales – sold in varying weights (also float when dropped in water.......so I’ve heard:wh). Do they weigh correctly? IMO yes as far as angling scales go.

watatoad · Jul 5, 2011

I have my scales checked every season and certified every 3 years, yet I never weigh my own catches.

Poshpaul (Angling Trust and PaSC) · Jul 5, 2011

barbelboi,

Got the same myself...never bother using them yet...(why bother when Spiders weights them for me on his scales!!

).

I gather that they are ok. You need to be very careful having zeroed them as slight jolts, or not holding them straight, can move it off zero v. easily apparently.

The more expensive RH scales are v. accurate I'm told but can't say my use of scales justifies the expense (nor does my bank balance!!!)

Trent Jim · Jul 6, 2011

My scales are digital, came from the far east, were sold as luggage scales, cost about £3 and go by the name of "jinger"...

I was understandably sceptical about the accuracy, so tested them using 2litre pop bottles filled with water.

the bottles were part filled, and accurately weighed on digital kitchen scales. 1 bottle @ 1lb, 1bottle @2lb, 1bottle @3lb and 10 bottles 90%(ish) full @ 4lb each.

Using these bottles i was able to produce a calibration curve that showed that they were consistently accurate and reported about 1.5% under actual weight (.5oz under @ 5lb, 1oz under at 10lb, 4oz under at 46lb).
The one thing I havnt got around to checking is if the accuracy varies with temperature and if things have changed with 2 yrs use. (must start saving bottles again to redo the experiment)

by the way, using the same method shows that the accuracy of these is much better then the expensive Rapala digital scales I used previously (gave inconsistent results), and also much more accurate than my old flyweights (which weighed light at the bottom end of the range and heavy at the top)

Try it out for yourself - it doesnt take long

Bob Hornegold · Jul 6, 2011

As a Records Officier for a Modern Specimen Group, I need to know my scales are correct.

There is a place in Camden that calibrates scales, so a mate takes them there ( he has a shop next door).

I have 2set of Samson Digitals and a Ruben Heaton set for the really big stuff.

Bob

stuart1988 · May 5, 2013

trentjim said:
My scales are digital, came from the far east, were sold as luggage scales, cost about £3 and go by the name of "jinger"...

I was understandably sceptical about the accuracy, so tested them using 2litre pop bottles filled with water.

the bottles were part filled, and accurately weighed on digital kitchen scales. 1 bottle @ 1lb, 1bottle @2lb, 1bottle @3lb and 10 bottles 90%(ish) full @ 4lb each.

Using these bottles i was able to produce a calibration curve that showed that they were consistently accurate and reported about 1.5% under actual weight (.5oz under @ 5lb, 1oz under at 10lb, 4oz under at 46lb).
The one thing I havnt got around to checking is if the accuracy varies with temperature and if things have changed with 2 yrs use. (must start saving bottles again to redo the experiment)

by the way, using the same method shows that the accuracy of these is much better then the expensive Rapala digital scales I used previously (gave inconsistent results), and also much more accurate than my old flyweights (which weighed light at the bottom end of the range and heavy at the top)

Try it out for yourself - it doesnt take long

I hope for your sake it was a pint and a litre as a pint weights 1.04lbs and a litre weighs 1.75975 lbs the best way to check calibration is to weigh the maximum potenital of the scale so for example if it weighs 20lbs put 48 £1 coins it will weigh just over 20lb

aebitim · May 5, 2013

stuart1988 said:
I hope for your sake it was a pint and a litre as a pint weights 1.04lbs and a litre weighs 1.75975 lbs the best way to check calibration is to weigh the maximum potenital of the scale so for example if it weighs 20lbs put 48 £1 coins it will weigh just over 20lb

1 litre of water weighs 1 kilo which is 2.2 pounds this is the basis of the metric weigh system.

captainbarnacles · May 5, 2013

if i had 48 £1 coins i'd buy some new scales he he

terry m · May 6, 2013

If perfect accuracy is required, then ring your local trading standards and they will be able to check them. But they may not be able to adjust them (dependant on the type), they should be able to tell you how far out they are per kilo or pound.

laguna · May 6, 2013

1 litre of water = 2.2lb + its container!

A crude test to show the differences between scales...
hook up your cheap bargain scales with your mates posh digital and tie off against two trees and read - you will be surprised how little it proves :wh

pentaxman · Nov 24, 2013

Accuracy of scales can never be assumed unless they have been calibrated which would normally mean they come with a certificate, that includes new out of the box items.

Even scales used to weigh items in shops which have to be trade verified have a tolerance they are allowed to work to.

Your best check is to match the maximum weigh of your own scale against a trade verified scale and weigh at this level.
For inspection by trading standards, the tolerance allowed is 3 of the smallest division withing the useage range at the maximum weight of the range.

Eg. a 6kg scale reading by 1g will be allowed to be 3 grams out at 6000 grams.

The Samson scales are adjustable to make them read correctly.

My credentials for the above statement?
I am a scales engineer (not trading standards) trained to verify scales.

binka · Nov 24, 2013

Thanks for that pentaxman.

I've sold many Samson scales in the past for postal use and bought a set of the generally highly regarded Reuben Heaton Flyweight Mk2 Scales and have serious doubts about mine in that they seem to weigh as differently as there are days in the month and are more than 10% out when weighing household items.

I'm wondering if I've got a dodgy set as they are also a nightmare to zero?

Does anyone know if scales generally should be zeroed under tension of a sling or net as I always rest a fish in the landing net before unscrewing and weighing which means I have to zero the scales without load?

pentaxman · Nov 24, 2013

Technically scales should be zeroed under no load conditions.
No load means that they should not have a load applied, but zero should take account of any weigh plate or frames required.

Ideally, hand held scales should be held by their upper mount or hanging bracket so that the scale can find their own vertical resting position. They then should be zeroed (often shown on the button as a 0 with arrows pointing to the 0 on both sides).

The sling or bag and any ropes to mount them should then be hung and if the scale has it, the scale should be Tared which is a T button with or without arrows.
There is normally an indicator on the screen which shows you are now measuring a "Net" weight (non fishing version of the term). Fish can now be added.

Scales without tare facillity require the same thing to be done but using the zero for a second time rather than the tare button.

Household scales are very hit and miss as regards to accuracy so they are not a good guide.

Your RH scales sound like they are not hanging properly to get the zero or the mechanism is bent / damaged / binding.

binka · Nov 24, 2013

pentaxman said:
Your RH scales sound like they are not hanging properly to get the zero or the mechanism is bent / damaged / binding.

That's great thanks for that, I was even careful enough not to be sold the display model which I like many before me no doubt had given the usual once over by way of pulling, dropping and who knows what else.

Mind you i'll be reluctant to get rid of 'em as they do seem to be weighing heavier :wh

sam vimes · Nov 24, 2013

binka said:
I've sold many Samson scales in the past for postal use and bought a set of the generally highly regarded Reuben Heaton Flyweight Mk2 Scales and have serious doubts about mine in that they seem to weigh as differently as there are days in the month and are more than 10% out when weighing household items.

I've had similar experiences of the Flyweights. They are OK for an approximation that's marginally better than a guesstimate. Beyond that, they're poor. Nigh on impossible to zero and don't necessarily return to zero. Because of that they're odds on to be out two or three ounces under or over. If I want a reasonably accurate (I've checked as best I can and compared them to several other scales) I take my Chub digitals. I have misgivings with digitals, mostly battery related, but I'm happy that they are reasonably accurate without going the whole hog of full on calibration. Ultimately, I'm not that bothered if they're a bit out, I'm not claiming records. I guess the vast majority of anglers will be the same. A few ounces really don't matter. Even a few pounds isn't going to matter much in the overall scheme of things. Besides, I'm consistently disappointed by the way that fish tend not to weigh as much as they look like they will!

It's always the scales fault!

chav professor · Nov 24, 2013

binka said:
Thanks for that pentaxman.

I've sold many Samson scales in the past for postal use and bought a set of the generally highly regarded Reuben Heaton Flyweight Mk2 Scales and have serious doubts about mine in that they seem to weigh as differently as there are days in the month and are more than 10% out when weighing household items.

I'm wondering if I've got a dodgy set as they are also a nightmare to zero?

Does anyone know if scales generally should be zeroed under tension of a sling or net as I always rest a fish in the landing net before unscrewing and weighing which means I have to zero the scales without load?

I like to rest fish in the net in the margins. Gives time to zero scales, prepare camera equipment and get organized.

Always brought up to tension the scales... I have a small Reuben Heaton weigh sling that I wet and keep in a fresh clean plastic bag (just dunk it in the river in the landing net prior to actually fishing). It will never weigh the same twice, so zeroing each time is essential - tensioning the scales.

The plastic bag stinks of fish and gets chucked at the end of the day (or night)... the weigh sling dried between sessions.

Avon scales? Had mine calibrated last year and are kept clean and dry. DO NOT SPRAY INSIDE WITH WD40 - this destroys their accuracy!!!

binka · Nov 24, 2013

sam vimes said:
Nigh on impossible to zero and don't necessarily return to zero.

Cheers Sam, I'm glad it's not just me.

I've spent ages zeroing the scales before at home only to give them a steady pull on the hook and see them settle back to 12oz

It's very rare I weigh a fish so not really a big problem as much as one of those baffling things that niggle away at me.

---------- Post added at 22:35 ---------- Previous post was at 22:33 ----------

chav professor said:
DO NOT SPRAY INSIDE WITH WD40 - this destroys their accuracy!!!

Hmmm... that's given me an idea

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