Dual holder 3D model is different?

[JMik3]

Hi, thanks a lot for sharing you project.

I just want to ask you why the Dual Holder is completely different. How it is supposed to be used.

I am interested in using the Dual holder to have a full bridge and connect it to the Leobodnar BU0836-LC.

The single holder 3D model is easy to understand but the Dual Holder I am not sure why it is like that.

Could you please explain it and how to mount it?

PD: sorry if my english is not good enough :).

[GeekyDeaks]

Hi @JMik3

It's a bit of a long story, but the short answer is that it was the first attempt at the model and it had some issues.

To elaborate a bit more, we found the following problems:

1. the model doesn't fit inside the case - this was not a problem for me because I had mounted them outside the case, but my friend was still using his and we had to hack quite a bit of the model away to get it to fit.
2. There is very little room at the top of the model for allowing compression. I didn't really think this through fully at first, but because the piston has to always be in contact with the loadcell, it means all the compression has to occur at the top of the piston. Since we left very little room, the pedal felt really hard
3. The two loadcells have to be able to move very slightly down, this meant you need a little spacer between the two to stop the top one simply resting on the bottom one and preventing it from working. In CAD it looked OK, but when it was printed the two cells would just rattle around
4. finally, and probably most importantly, I made the mistake of thinking the two cells would give a 50kg range, but this doesn't work when they are in series, so other than getting slightly better resolution the added complexity to the design didn't seem worth it

I'll dig up some pictures of how the piston was assembled with the dual cell, but there is actually a photo of it in place that might help for now in the code

[GeekyDeaks]

Hopefully in the above you can see the two cells and the little spacer in between. The spacer model can be found in the code dual_spacer.stl

[GeekyDeaks]

Another photo showing some rubber washers on the bolt I was using as the piston.

[GeekyDeaks]

I just looked at the BU0836-LC - I think you can simply use two 1k resistors to make the other side of the bridge and then stay with the single cell model. I can help with the circuit if you want as it would be trivial and you can probably mount the resistors directly to the screw terminals of the board

[GeekyDeaks]

Hey @JMik3, I just realised that @Locoblade already posted a diagram with the same board and the two extra resistors. You can find it at the end of #1