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Experiment: Force exerted by Model S door handles on closure

Discussion in 'Model S: Interior & Exterior' started by wk057, Jun 12, 2015.

  1. wk057

    wk057 Senior Tinkerer

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    #1 wk057, Jun 12, 2015
    Last edited: Jun 12, 2015
    So, after much ado about this topic in another thread, I set forth the opinion that the door handle retraction couldn't possibly injure someone. Seems a lot of people disagreed with this, so, time for some facts and experiments in another wonderfully informative wk057 thread. ;)

    Hypothesis: Door handles do not exert enough force on retraction to be a problem. The handles do not retract under the force of a motor. Instead, the handles are released to their springs upon retraction and retract under the tension of the springs and even a minor obstruction (finger) will easily stop it.

    Experiment/Testing:

    Bought a force gauge (been wanting one anyway) to test this. I tested the gauge against some known weights before testing and it was spot on.

    Grabbed my SpaceX lanyard and went to work.

    First up, P85D driver door handle.

    p85d-handle-force.jpg

    Peak of 3.87 lbs of peak force on the springs. I made sure to keep the handle partially extended for the testing and did several tries. All were within 0.1 lb of this.

    I also tested the other handles, and the driver door actually had the most force. The others were between 0.1 and 0.2 lb less.

    Next up, the wife's P85.

    p85-handle-force.jpg

    Surprisingly a hair less force than the P85D, clocking in at 3.16 lbs of force peak. Tested her other handles with nearly identical results.

    So... how does this compare to some other handles? To the kitchen!

    fridge-door-force.jpg

    My refrigerator door takes 6.01 lbs of force to open.

    freezer-drawer-force.jpg

    The bottom freezer drawer takes 11.41 lbs of force.

    home-door-handle-force.jpg

    A random door knob near the kitchen needs 3.37 lbs of force (between the P85D and P85 handles).


    microwave-door-force.jpg

    Microwave door: 9.64 lbs.

    oven-door-force.jpg

    Oven door: 12.11 lbs.


    Conclusion: So, suffice it to say no one is getting injured by the Model S door handles. Let's just lay that to rest. If you can make popcorn or grab a beer without hurting yourself opening the microwave or fridge then you're not going to be hurt if the Model S retracts its handle on your hand.


    Note: I mentioned in another thread that as a result of a moderator here overreacting to a post of mine on this topic that I wouldn't be posting the results of my testing here on TMC in protest of this. However, after some thought, I don't believe there is another online community that would better appreciate the information than here, and I decided to just not let this moderator's error spoil it for everyone here. I appreciate the work the forum administration does here, and there isn't a better Tesla related community available. TMC is far better than the "official" forums at Tesla's website. In any case, I'll hope it was an isolated moderator having a bad day issue and continue on.
     
  2. Pilot_51

    Pilot_51 Member

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    I only read some of the posts in the other thread for context. As I gather, there are more variables at play than just the amount of force. The main issue seems to be the position of the fingers as the handle closes on them, in some cases pressing them against an edge. Force on a small area has more potential to cause damage than the same amount of force on a larger area. As you've shown, it's not going to cause injury, but that force can still mean a painful pinch under certain conditions. Just try opening one of those kitchen appliances with only, say, a paper clip around a finger tip. I suspect you might feel something resembling pain.

    My personal experience, so far, is that it is not an issue. I've closed my fingers in the handles a few times both intentionally and accidentally and did not feel any pain or see an impression on my finger, and removing my fingers was easy.
     
  3. deonb

    deonb Active Member

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    Mmm. Here's a very common household action that applies force to a small area (pressing down on the back of a blade with your finger). Wk057, do you have a way to test something like this?

    I doubt you would actually need a pumpkin. A pineapple probably requires more than 3lbs to cut into. Heck an apple might even suffice, but that's just a guess. (Would be interesting to know regardless).

    carve-pumpkin-1_3-800X800.jpg
     
  4. Zythryn

    Zythryn MS 70D, MX 90D

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    The force over a small area is likely the main issue, those reporting pain, ran into.
    Best bet is, if the handle is retracting, just leave your hand in there, pull back gently so that your fingers don't get pinched, and slide it out.
     
  5. cgiGuy

    cgiGuy Member

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    Silly to imply that the mere force by itself was the issue "at hand" when we all know it was the handle pushing the finder into the edge of the opening that the OP was talking about. And honestly, all your kitchen tests just lessen the credibility of your "scientific method" by showing that you're trying to spin it that way. But, to play along.. even your TWO cars in your garage have about a 18% difference in spring tension. Is it not possible that across the ~90K cars produced there isn't a higher percentage tension than your 3.87 measurement?

    So if someone's car had ~25% more tension they would have near 5 lbs of force. So, take a 5 lbs dumbbell and rest on on your finger, while resting your finger (topside) on an object with a 90 degree angle. See if it is uncomfortable or leaves a mark.

    Seems like more public shaming of someone who posted an instance where they thought it hurt a little. For the record, I've never hurt my fingers in the handle, but that doesn't mean that I'm going to assume everyone's handles and fingers match mine.
     
  6. Xenoilphobe

    Xenoilphobe Active Member

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    Thanks for the info - I have two kids and when we got the car I showed them that they could actually let the door handles close on their fingers and not get hurt. I suspect the pressure could hurt if you yanked your hand out at a weird angle, but that would be like slamming the oven door on your hand and I would attribute this to "operator headspace".
     
  7. InternetDude

    InternetDude Member

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    I got one finger tip caught by accident shortly after getting the car, it really hurt. I would say it pinched approximately half my finger nail, just the tip. Stick just part of your finger tip in there and see what it feels like when it closes all the way.
     
  8. wk057

    wk057 Senior Tinkerer

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    Looks like my post earlier never made it due to website database issues....

    Anyway, I tried letting it close on just my pinky finger and didn't experience anything even remotely resembling pain. I'm not a pain-doesn't-phase-me type, either... and my wife says I have softer hands than she does. If these handles would hurt anyone, it'd be me, and they don't.

    I'll bring up a quote from another thread about my 2 year old niece (just turned three):
    As for force on a small area, my force gauge does have a push measurement function, so might mess around with that a bit on some common small-area force tasks.... but even when those come back as more than the force the handles exert there will still be people claiming otherwise based on the posts here. On that note, I tried opening my fully stocked bottom freezer drawer with just my pinky finger also. Was a little difficult to get a good grip, but I did that 12 lbs of force needed with zero pain.

    *shrugs*

    I personally find it kind of funny that people claim they're being hurt by them. It's cute.
     
  9. bonnie

    bonnie Oil is for sissies.

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    As I posted in the other thread ... just because ones tested don't cause any problems, it doesn't mean there is nothing wrong with the set in question. THOSE are the ones that need to be tested & I hope MileHighMotor heads over to his service center to get them checked out.
     
  10. wk057

    wk057 Senior Tinkerer

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    I think you're exaggerating a little here and extrapolating based on data that you don't have.

    First, I tested eight handles, not two. The highest out of the eight was 3.87 lbs, which was ~0.2 lbs higher than the next highest. The lowest was actually 2.88 lbs, which was ~0.1 lbs lower than the next lowest. Average between the eight was about 3.36 lbs. 25% more than the highest reading would go against all of the data I have, but you're welcome to do your own testing and find data that supports that.

    Also, the P85 is about a year older than the P85D so it would make some sense that over time the springs have slightly less force than they originally had. I've never heard of a spring gaining additional force over time.

    As for public shaming... no, not my intention. Admittedly, as I posted above, I laughed at this "issue," especially when the original thread title of the other thread was something along the lines of "the door handle tried to take my fingers off" or something. But not trying to shame anyone, just bringing to light objective information.

    Also, the body edges on the door around the handles are not 90 degree creases. They're smooth and beveled. They are pretty similar to the bottom crease of a soda can (not the top of the can, which is a more harsh crease).

    If there are other objective tests I can perform I can certainly try them.

    Edit: I'll also be at the service center sometime soon and can ask to test other cars. :)
     
  11. Krugerrand

    Krugerrand Active Member

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    Give me a break. You've more than been laughing at the 'issue'. You've been laughing at the people, and you know it. When you say stuff like: I personally find it kind of funny that people claim they're being hurt by them. It's cute. , you're being a dink.
     
  12. bonnie

    bonnie Oil is for sissies.

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    But why? What will more data prove? Seriously. Isn't it possible that ONE car has a problem?
     
  13. Electric700

    Electric700 Member

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    Thanks for the thorough writeup, wk057!
     
  14. wk057

    wk057 Senior Tinkerer

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    I guess I'll rephrase to it not being my original intent, but as people continue to press it, against the evidence, it's starting to just be silly. Am I not the only one that finds it the least bit funny that grown folks are claiming to be hurt by a few lbs of force when a 2 year old doesn't have such an issue? I mean come on, that is textbook humor right there.

    Not this problem, no. The way the handles are designed I don't see how it would be possible there would be any significant factor of force greater than what I measured, and certainly no where near anything that could be of concern. The way the spring sits in the assembly is low below the handle, if I recall correctly, and it exerts it's force at that shallow point with very little travel on that end. The handle itself is at the travel side of this basic lever assembly. So, even a spring that is significantly out of spec would still have a small impact on the actual force on the handle. I mean, we're talking even if it were 100% out of spec (double the force) it's still less than you exert opening a microwave.

    I think the handles are capable of exerting pretty significant force upon extension, but not retraction, and this is very obvious in the design.
     
  15. bonnie

    bonnie Oil is for sissies.

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    We'll have to disagree, then. I've let my hand sit in the handle when retracting and it was insignificant. But I can acknowledge that someone else might have a different experience with their particular vehicle. He's clearly not trolling the board. I'll just leave it there.
     
  16. wk057

    wk057 Senior Tinkerer

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    Not 100% sure I agree, especially given the original title of the other post... but... ok.
     
  17. Krugerrand

    Krugerrand Active Member

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    There are a lot of silly things going on of late on this forum and I'm including you in some of that silliness. But I am entertained, that is for sure. Some day I will learn (or someone will instruct me in dummy terms) how to embed video.

    Are You Not Entertained? - YouTube
     
  18. bonnie

    bonnie Oil is for sissies.

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    embed video.png
     
  19. Krugerrand

    Krugerrand Active Member

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    Ah, snap! That looks too easy to be true. It's got to be a trap.
     
  20. bonnie

    bonnie Oil is for sissies.

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    You DID say you wanted it in dummy terms.

    :)
     

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