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load

Hardware and Electronics Used: Arduino UNO, HX711 ADC Load cell amplifier, Load Cell (2Kg); Currently, I am working on a project which requires me to put load cell along with the other circuitry in an enclosure to make it water-resistant... But while doing so, the weighing platform and the base come in contact (as shown in picture 2). This messes up the readings. I 3D printed various loading styles and tried out a few different configurations but none of them seem to work. The configuration that is shown in Image1 is an ideal one that yields precise results irrespective of where you place the load on the weighing platform. The configuration in Image2 yields fluctuating readings which make no sense whatsoever. Can you suggest to me some way by which I can design a proper enclosure around the load cell and the circuitry in order to get proper readings and also keep it water-resistant?

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  • $\begingroup$ What class of water resistance do you need? Does it need to withstand things like rain/splashes or does it need to be submerged in water? $\endgroup$
    – elementiro
    May 29 at 19:06
  • $\begingroup$ If you see fluctuations, that indicates that the box is vibrating when the weight is put on it. First, you will need to damp out these vibrations with a viscoelastic silicone sealant (for example). Next, you will need to compute the effect of deformation of the vertical sides of the box on the weight that's measured and correct for that. I'm assuming the box is submerged in water. Alternative designs can be thought up if that's not the case. $\endgroup$ May 29 at 22:22
  • $\begingroup$ Does the load cell need to go in the water? Perhaps you could arrange things such that the load cell is in air and the weighing platform is suspended under the water. If the water is in a tank or bucket, you could use the load cell to weight the mass of the container of water and the object in the water and again avoid the problem of making your enclosure watertight. $\endgroup$
    – D Duck
    May 29 at 23:47
  • $\begingroup$ No. It is not going to be submerged in water. I need just a basic water resistance against splash. I want to fit this at the bottom of a cylindrical container (like a water bottle) that carries a liquid solution. It tells me the weight of the solution in the container. In a nutshell, somewhat like designing an analytical weighing balance that attaches to the bottom of a cylindrical container. $\endgroup$ May 30 at 0:54
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Because 3d printing a hard case solution, will create a hard barrier which will affect the weight measurement, you'll probably need to consider some sort of flexible isolation method.

A quick (and not so eye pleasing solution) if

a) the project does not need to be submerged in water

b) if you are not so much bothered about appearances

is to consider isolating with a thin film of small weight. One possible solution for that (and depending on the size of the load cell would be to use an ultra thin transparent nylon bag.

enter image description here

You either

  • put the load cell inside the plastic bag and zip-seal around the cable going in.

OR

  • you could 3D print a box to house the load cell and then put on top a very loose plastic film.
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  • $\begingroup$ To be honest, I don't think wrapping it around a thin film would work. It will be fragile. Considering the working environment, I require it to be a little rugged. Just rugged enough to withstand a drop from lower heights. What I am unable to do is preserve the underlying principles of the config shown in the image1.If you observe, the left half of the load cell is in contact with the ground, and on the right half is the weighing platform which isn't in contact with the ground. When I design an enclosure in 2 halves(top&bottom),the right half of the load cell and the left half come in contact. $\endgroup$ May 30 at 2:49
  • $\begingroup$ OK fair enough. Although you should update your initial post to add that specification (i.e. to be able to be dropped from a small height). Additionally (if that's the only drawback), depending on the material of plastic bag you can have different quite good abrasive properties (see nylon or silicone freezer bags) $\endgroup$
    – NMech
    May 30 at 4:57

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