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Joined: Mon May 20, 2019 10:30 am

Volume Scale

Mon May 20, 2019 1:32 pm


I need some help with a project. I would like to build a volume scale which gives me the dimention and weight of the item, and imports it directly in an Excel file. I figured I would need 4 things to make it happen:

- 1 EAN barcode reader (to scan the the item and create a new line in Excel)
- 3 Lasers (for hight, width and length)
- 1 scale (for the wieght)
- 1 Raspberry Pi ( to collect all inputs and forward it to a pc)

Since I'm new to Raspberry Pi I don't know which one would fit my needs and what hardware to use in terms of laser, and scale that are compatible with Raspberry Pi. Both the scale and the laser would have to be quite precise, the scale to 100 gramm and the lasers to 5mm but the laser will have to measure at most 2m.

Here is a link which is pretty much what I have in mind. ... 3d-silence

Thank you for your help.

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Re: Volume Scale

Mon May 20, 2019 1:44 pm

Sparkfun have some IR distance sensors that would be compatible with the Pi. They claim 5mm accuracy and are much cheaper than laser options (which sparkfun have some of too)

PiMoRoNi also have a time of flight sensor which is less accurate but comes with code for the Pi

Sparkfun also have a tutorial to hack a set of electronic scales, same principle could be applied on a Raspberry Pi.

As for which Pi to use. Just go with the top spec model, the 3B+
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Location: Sydney, Australia

Re: Volume Scale

Tue May 21, 2019 7:30 pm

To get the millimeter accuracy your require, will be hard with DIY lasers.

I would seriously look at MAchine Vision, as this is the way the commercial volumetric scanners are going.

You would need two cameras, one looking down to determine width and depth, and one from the back to sense width again and height.
..the only thing worse than a stupid question is a question not asked.

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Location: Oxford UK

Re: Volume Scale

Wed Jun 12, 2019 4:07 pm

a simple solution could be derived from displacement. fill a box with table tennis balls, push an object into the full box, and the number of tennis balls spilt out of the box will give you an estimation of its volume.

making it a manual task to insert the object into the ball box to displace the indicating balls reduces the electronics to the interface for the scales weighing the spilt balls but a stepper motor drawing an object down into the box could be used with a net and cable?

automatic ball return and box filling shouldnt be too challenging if required

a little testing of objects of a known volume in the style and shape of those expected should be enough to tune it to a reasonable degree of accuracy.

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