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Load cell hell!

Discussion in 'Sim Racing Hardware' started by Paul Hamwa, Dec 22, 2010.

  1. I recently made a homemade set of pedals with a load cell.

    I'm having problems calibrating the load cell. A funny thing happens, when I press the pedal the slider moves back and then forward. It starts in the middle so its as if there is already pressure and then by pressing the pedal it relieves it for a second. Once the pedal is too the stop and I really stamp on it, it starts giving a reading again. Weird

    Anybody have any experience with this???

  2. sounds almost like you have a negative load on it, then as you press the pedal, it reaches the mid point, (no load) before giving a response again. Is there a way you can check to see if you have no pressure on it when the pedal is at rest?
    Maybe have the cal screen open, the loosen the pedal, and see what happens.
  3. Yeah that's exactly what it does, it starts with load and moves back and then to the mid point (where it started). I just thought that if it started at a certain point with a little load on it, it would then just move higher on the scale, but not backwards?

    What would a negative load be? Is that when the cell bends in the other direction, down as opposed to up?

    I've loosened the pedal but it doesn't seem to change anything.
  4. could you put a couple of thin shims maybe around .250mm under the mounting bolt to raise one side up? and yes, by negatice i mean its lower then it should be, you press the pedal, it raises it to the 'at rest' center point, then further pressure moves it in the direction its supposed to do.
    Have you also tried Todd's DiView program from his site? there may be a couple of calibrating programs you can use. (cst pedals)
    Hope that helps!
  5. great idea for the shim I'll give that a try :) I do have DIView, that's where I've been fiddling around with it. I haven't found a combination saturation/calibration that solves the problem though, so my guess is a mechanical solution like the shim would work. The metal I used where the load cell sits might be uneven ever so slightly. Todd mentions having to activate "zoom" in the calibration tool, when I do that I don't get any reading at all. Only at the "normal" does it work. I used a little length of cord to extend the load cell wires because it wouldn't reach the box where the Bodnar controller sits, from what I've read that shouldn't make a big difference. But maybe it does?
  6. @simracn you were right! Thanks!!! To test I shoved a doubled up piece of card-stock paper under the spring side of the load cell and it goes over the mid point.

    I'm thinking maybe it would be better to unscrew it and put the shim under the screwed down side to relieve the pressure as opposed to augmenting it. But for that I gotta unscrew the whole thing and rewire!!! argh! Oh well that's homemade for you.

    One thing I can say is these pedals are Incredible to drive with, just tried NKpro and Kartpro! WOW! Having so much range in the gas pedal is heaven!

    For the brake I'm wondering if I should have a short spring range and a lot of braking after the stop, or vice versa. I'm thinking they should be really stiff? Then again I've never been in a real race car! ;)

    Two weeks work weren't in vain!!! :)
  7. good deal!!! glad could help :) i have a set of home built CST's and i just left the brake travel at about 2 1/2 to 3" I have the standard load cell. so its not real stiff. but to me its pretty close to a real car. and the way i have it setup, i can heel brake, toe gas. my foot doesnt like to twist the other way :) just took some adjusting of where the travel was on the pedals to get the best feel and positioning when the brake was pressed for hitting the gas.

    have fun with them and congrats on a succesful build!

    Attached Files:

  8. Nice one Charlie :)

    Thanks for helping Paul out (another nice CST pedal build I see, good job!)
  9. yeah I second that! Thanks again! :) Great advice here at RD!

    I recommend these pedals to anyone with some time on their hands they are soooo worth it!!! Even though I'm still a bit crap, it's amazing how much steering is effected by the pedals.

  10. just glad my suggestion worked and may help someone else too :) And thanks for the compliment on the pedals. been going strong for over three years now. I agree Paul, may not make you faster, but it sure helped me be a bit more consistant!

    Once i get my real seat instead of my home made intermediate road seat, i'll post more pics of the cockpit in the proper thread. unless anyone may be interested in the seat as a cheaper way to get a pretty comfy one. and i dont fall out anymore on the short ovals LOL
  11. I bought the Cannon DIY guide about 3 years ago. I never did anything other than stare at it. I have now begun to order parts. I am working out of town so I brought my DFP wheel with me. My rig has a G25. Now I know I need CST Pedals!

    Haunting issue: I need a better photo of the production pivot plate, and a description of what is in between the two plate where the knob is. There is clearly a gap. The DIY guide mounts the cell in a completely different manner. I want to do it more like the production set.