REFLECTOR: Low Cost Electronic Scales

[Ron Brown]

I swiped this off canard-aviators at yahoogroups.com - Ronnie

Posted by: "Harley" harley at AgelessWings.com   harleydixon 
Wed Jul 4, 2007 10:18 pm (PST) 
Canardians...

I just couldn't resist passing this info on to those of you who may be  interested.

I was in need of a new scale for weighing the epoxy/hardener (actually, the filler and the primer and their components now), as for some strange reason the old Pelouze I've been using on my Long EZ project for the last 10 years is pretty much covered in this strange, hardened, plastic-like material! Not sure where that came from...it must condense 
out of the air overnight.<G>

Anyway, when I was at Harbor Freight yesterday, I picked this one up- go to: www.harborfreight.com  and enter 95364 in the item # search box. knowing that if it wasn't accurate or repeatable enough for my construction use, I could always use it for my postal scale, as it has almost three times the capacity as the Pelouze I use now does (11.5 pounds vs 4 pounds).

A little background...
When I used to worked for a pharmaceutical company for a living, we did weekly calibrations on scales and load cells we used in the manufacturing systems I designed. When I retired, I rescued those poor old weights, knowing that I could probably use them at home sometime (When I left, they contracted out the metrology work and the equipment 
we used just sat around until they tossed them out...in my direction.)

A calibration check on the Harbor Freight torque wrench a few years ago, showed that it was more accurate out of the box (it was the only one we tested that WAS calibrated out of the box), and held the accuracy over longer use than other more familiar (and far more expensive) brand name wrenches we investigated. So, I was not surprised when this new scale surpassed all my expectations.

Unlike the Pelouze, the Harbor Freight unit read in 1 gram increments (or 0.05 ounces or 0.1 pounds) to a maximum of 11.5 pounds, or 5kg or 176 ounces (mode selectable).

And totally unlike the Pelouze, a one gram weight produced a one gram reading change, not just when it was the only weight, but even at a random weight of 4717 gms, putting the one gram on it changed the reading to 4718 gms. Removing the entire random weight, the reading returned to zero. The Pelouze needed at least 10 grams to change the 
reading (even when new), and from heavy weights near it's limit it would not return to zero, or read the same negative weight after taring.

But, like the Pelouze, the weigh platform comes off with a quarter turn, so I covered it and the unit under it with plastic wrap to delay the inevitable plastic buildup, and popped the platform back on to protect it all from spills. Didn't affect the calibration a bit.

In short, it is as accurate and repeatable as the $4500 Ohaus electronic lab scale that our company insisted we used. One of which I rescued from my company and repaired 20 years ago when I started this project. 

And The Ohaus lab scale only had a 500 gram limit. This Harbor Freight unit actually surpassed the specs we had for our work scales, even though the Ohaus scales we used often did not and had to be sent out for rebuilding.

So, if you need a scale, I would HIGHLY recommend this one (even though it's price online is $4 less than I paid for it at our local store yesterday <G>). For our use, I think it's accuracy is overkill, but then again, who can beat the $16 price (plus tax, shipping and recappable tire)? <G>

Harley Dixon
Long EZ N29EZ
Canopy done, Filling and sanding the wings now.
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