Build a Thin, Durable Scale for Rough Terrain: Force Sensor Options

[refind]

My task is: I need to build a very thin scale (like a bathroom scale), less than 8mm in thickness total, and needs to work even if placed on rough terrain (so it needs it's own bottom and top). The total load will not exceed 10kg.

I've been trying to look for the correct force sensors to use but I haven't found anything too attractive. Load cells are large and expensive, strain gauges look promising but I'm afraid of bridge balancing issues, and force sensing resistors are garbage because of drift. I need accuracy of +/- 5% or better, so does anyone know any sensors I could try?

Thanks!

 

[dlgoff]

Here's some Subminiature and Miniature Compression Load Cells.

According to the Specs, the 20 kg capacity http://www.omega.com/pptst/LCPB.html is only 4 mm thick. Here's a dimensions picture from their specifications PDF file.

 

[refind]

This is a good product but buying 4 for a scale would be $480. I need to make several of these scales so the cost adds up too fast.

How do they make bathroom scales for $15?

 

[dlgoff]

This is a good product but buying 4 for a scale would be $480. I need to make several of these scales so the cost adds up too fast.

Ah. You did say ±5% and be 8 mm thick.

How do they make bathroom scales for $15?

I don't know. Maybe that would be a good place for a little hands-on.

 

[davenn]

Ah. You did say ±5% and be 8 mm thick.

I don't know. Maybe that would be a good place for a little hands-on.

for a $15 investment to strip one and do some reverse engineering would be $15 well spent in my book

Dave