Miniature tension load cells

Are there any that are.. affordable?

I got quotes for some of the top results on Google, and they're extremely expensive. iPhone expensive. For example, FUTEK's LSB200 are ~$1000 a pop.

Are there any smallish compression/tension load cells in the $100-200 ballpark? I don't really need the measurements quality you get from these high end ones (would be nice though), but size is an issue with the ones I'm currently using.

Thanks!

You could take one out of a small weigh scale like this one. I did - it's not hard to do. Not sure they're small enough - you didn't say how tiny they need to be. Just guessing, mine is 50mm to 60mm long (and obviously nowhere near 10kg capacity of your current cell).

Oops - you said "compression/tension" load cell and the post subject is "tension load cell," but the one you're currently using is a beam load cell (like the one in the scale that I linked to). What are you trying to measure and how are you attaching the load cell?

Hi,

I'm trying to measure the tension of a rope that is attached to a finger. Think instead of the bands shown in this video is a rope that on one end is tied the finger and on the other end to the load cell. If I were to find one of these, I guess attaching it to the screw would work.

Since beam-type load cells generally don't care where the load is applied, you could do that with a beam-type load cell, provided that you add "arms" and a hook or eye to both sides of the cell, centered on the length of the cell, so it doesn't rotate under load (essentially making an "S" type load cell).

Or, buy a small cheap digital fish weight scale and see if you can hack what's inside.

Can you clarify the setup you described in the first paragraph? Sorry, I'm a bit new to this. Did you mean a different load cell than the one I'm using now? Did you have a particular one in mind that isn't as big? I'm going to have 10 of these, each connected to a finger, and eventually the whole device needs to move horizontally, above the piano keyboard. Using smaller ones will really help with the setup.

Something like the image below…yes, using a load cell similar to the one you have now, if you can find one that has the capacity you need and is small enough. No, I don’t have one in mind that isn’t as big, other than the one I mentioned in my first post. It’s smaller than the Sparkfun one you’re using, but has a fraction of the capacity (but you didn’t say what capacity you need). Even at 50mm or 60mm, it’s still rather clunky.

Capture.JPG

PS: I didn’t watch your video - don’t care to click on random links like that, sorry.

If you're willing to pay $100 to $200 for each load cell, as you indicated, then if I were you, I'd call some of the regular suspects (omega, honeywell, futek, etc.) and see if there is anything they can do for you, or if they can recommend a source.

Google is great, but sometimes it makes sense to just talk with a human being...

How about this one: https://www.amazon.com/Shaped-Electronic-Balance-Weighing-Sensor/dp/B00CW916C8/ref=sr_1_16?s=kitchen&ie=UTF8&qid=1481939774&sr=1-16&keywords=LOAD+CELL&refinements=p_89%3Auxcell

Thanks for the drawing! Much clearer now. The capacity I need is tiny since it's attached to a finger which doesn't weigh much. It does need to be pretty sensitive because each finger doesn't have a lot of strength to pull the rope. The sparkfun worked OK in that sense so far. Here's the video I mentioned earlier with the rubberbands setup.

The general idea is to tie a rope instead of the band, with the load cell on the other end. Then a motor will control the rope to release it when the finger is pressed and pull it when not. I have no idea if it's going to work, but figured it's worth trying.

Funny thing is I did try to ask Futek's application engineer about that. The best he could offer was a 1-5% discount on a $1000 product IF you're in an Ivy league school and will end up publishing a positive review of their product. :wink: