Oct 3, 2012 at 8:02 pm #1294681
L EBPL Member
I have research other threads, but want to confirm: there does not seem to be a hanging scale for under $50 that will weigh a backpack up to 50 pounds [go easy on me.. I know that is a heavy pack, but sometime I have climbing equipment etc.], and able to detect 2-4 oz differences/additions.
My goal: weigh 2 packs while at car, and if need to re-distribute some 4-8 oz items, be able to weight the total pack weight again.
I bought a Air Weigh LS-300 Portable Digital Luggage Scale, and it claims to weight up to 70 pounds or so. But if I weigh a pack and then put in an additional 8 oz item, the scale is not affected.. it reads the same weight!
There are some other scales out there, but I really would like to see some reviews, because I hit it wrong with the Air Weigh LS-300!
I am gathering my desire for a 50 pounds hanging scale, that will detect 2-4 oz difference is not available, or a very costly item if you want it to work right?Oct 3, 2012 at 8:12 pm #1917973
Mark VerberBPL Member
@verberLocale: San Francisco Bay Area
I don't know of any. A few years ago we tried a couple luggage oriented scales and they were all terribly off. My memory is that the best option we found was a Berkeley Fishing Scale. My memory is it was accurate to wit-in 1/2 a lb, but it certainly didn't deliver within an ounce accuracy. Repeated weighting would produce different results and the average of the various weights was often not within 1oz of what we knew to be the correct weight.
–MarkOct 3, 2012 at 8:24 pm #1917977
Lance MBPL Member
I use a Berkley FS50 fish scale which read in pounds and ounces up to 50 pounds. It has been pretty accurate when comparing total pack weight to the sum of my gear list.
I just now weighed my gym bag and then added an eyeglass case. The scale registed the 3 ounce difference.
I think I paid about $20 five or so years ago.Oct 3, 2012 at 8:37 pm #1917982
L EBPL Member
Thank-you so much for the responses!
I tried the Air Weigh LS-300 Portable Digital Luggage Scale once more… seems to be OK now. As long as I FIRST put something on the scale that is a bit heavy ( like something that is 3 pounds), and THEN add the smaller item ( for example a 10 oz item). It then shows the 10 oz difference. The actual item weight 11 oz but this is good enough for me for my weigh-at-car use. [ I thought this was not working earlier but it seems to be working now]
The Air Weigh LS-300 Portable Digital Luggage Scale cost around $12 from Amazon, plus shipping. Will try to let others know how it goes in practical use! But it seems it might be good for what I need ( weighing 2 packs while at car, and redistributing some lighter 4-8 oz items between packs ).Oct 3, 2012 at 8:54 pm #1917989
This is one of the first results on google. Maybe search for reviews.
http://www.americanweigh.com/product_info.php?cPath=46&products_id=485&osCsid=nlemnq8fkc33sphjrde9vv3fr0Oct 4, 2012 at 8:28 am #1918118
James MarcoBPL Member
@jamesdmarcoLocale: Finger Lakes
Check some Bike Scales on Google.
I have one that will handle 50#, requires a minimum of about 4 oz and gives accuracies of under a half ounc (10g.)Oct 4, 2012 at 8:05 pm #1918305
Mike BozmanBPL Member
What you are asking for is a scale that has an accuracy of .125%. Not to sound mean or anything but that is crazy. Damn well lab grade stuff! I have taken training at the National Research Council in Ottawa (home to the scientist that tell Canada exactly how much a kilogram weighs and how long a meter is). The course was on pressure metrology but specialized in sources of error. It can still be applied to measuring mass though. A gauge's accuracy is based on the smallest accurate unit divided by the total range of the gauge. In this case 1 oz/50 pounds. Or 1 in 800. A 1% gauge (accurate to 8 ounces on 50 pounds) is not bad but it seems as though you want more accurate than that. Unfortunately gauges are only accurate in the middle 50% of their range. Thus a 50 pounds gauge is a good range for the light backpacking crowd. But, again not to offend, you may be "picking fly fecal matter out of pepper". I would just use what you have now and accept that there will be some error. A few ounces this way or that way between packs is not going to make or break a trip.Oct 4, 2012 at 8:12 pm #1918306
@b-g-2-2Locale: Silicon Valley
Mike, most of the people here are confusing accuracy with resolution (granularity).
They want to add on a tiny bit of weight and see the display numbers change, regardless of whether the display is a few percent in error.
–B.G.–Oct 4, 2012 at 8:34 pm #1918311
Ken T.BPL Member
Exact weight. Isn't that what the spreadsheets are for?Oct 5, 2012 at 12:02 am #1918344
Franco DarioliBPL Member
If I read the OP comments correctly, he wants to equalise the weight of two packs or at least detect a difference down to 4 oz.9or 1 oz according to the title)
I can't see how a spreadsheet will unable you to do that in practice (IE not in theory)
The difference between the two (theory and practice) here is that it may not be all that easy to keep track of exactly what you put in the two packs particularly when you add food and water and maybe fuel.
for all I know you could have 4 oz of dirt and grime that your spreadsheet is not aware of…
Now as for how exactly 4oz would make any practical difference beats me but that is how I read it…Oct 5, 2012 at 5:16 am #1918357
James MarcoBPL Member
@jamesdmarcoLocale: Finger Lakes
Franco, yes, this is true. My 5 pound scale has an accuracy of a few grams. But adding this all up gives me a 15#4 pack weight for 5 nights out. Using the bike scale, it weighs about 15#8 at the trail head. I do not know why they are different, since both weigh a 4 pound weight almost identically (within 3-4grams on a metric setting.) I have almost given up on spread sheets, and simply use the total pack weight at the trail head unless discussing individual items.Oct 5, 2012 at 7:12 am #1918379
Marc PenanskyBPL Member
@marcpenLocale: Western NC
+1 to Mike Bozman's comments
I would also add that there is a big difference between "precision" and "accuracy". You can be very precise with inaccurate numbers on a spreadsheet and have a very inaccurate total weight. I would guess that most of the scales used aren't "capable" of the accuracy, precision or repeatability that we think we are getting when we weigh items or full pack weights. Just because a scale reads in grams or tenths of a gram, it does not mean it is accurate to that level. We often misrepresent accuracy by showing weights in a more precise manner such as smaller units or more decimal points.
I am not saying that manufacturers are trying to mislead anyone with false weights.
Measurement is a process that has many components of error that are additive and we only mislead ourselves when we take it for granted. I would really question accuracy on a home scale of a few grams in a 5 pound capacity scale. That 4 pound "standard" item that was used to check it (in the previous post) is probably inaccurate by more than that in it's actual weight.
Depending on the device being used, things like temperature, humidity, how and when the last calibration was done (if ever), was the scale properly zeroed, the quality of the actual device, and numerous other items can have a big effect on the accuracy of a weight measurement. My measurements are probably no better than others and my scale is not laboratory quality. I just try to represent the weights we provide in way that reflects their accuracy appropriately.
LightHeart GearOct 5, 2012 at 9:58 am #1918404
Steve KBPL Member
@skomaeLocale: northeastern US
I've been using one of these cheap $10 scales from Deal Extreme. It works alright. I'm not sure how accurate it is, but it works well enough for my needs.
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