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1 - What general direction should the head of a bent nail be clocked to?

Discussion in 'General Pinewood Derby Discussion' started by CastleCrasher, Feb 10, 2021.

  1. CastleCrasher

    CastleCrasher Pinewood Ninja

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    DFW, drilled straight, bent nail: what general direction should the nail head be clocked to? I understand whatever direction you get your steer tune like 4 over 48, but still what orientation? I had mine around 12 o'clock position, but another scout dad had his at roughly 6 o'clock, he's got derby "pedigree" you could say, their car was fastest at our race. I thought 12ish so the wheel moves out towards head, similar to rear wheels. The car with 6 ish looked like wheel rubs the body, at least just during a short roll on the table, he said it should move out to head going down the track. I also had a hard time getting the steer tuned right, just a couple degree rotation of nail changed the turn a lot or almost not at all. I should note that my bend probably wasn't great. Thanks in advance.
     
  2. Loud2ns

    Loud2ns District Champion

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    You want the axle bend to be down.....6ish.
     
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  3. T-Bone Racing

    T-Bone Racing District Champion

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    Agreed! But your wheel should not rub on the body! That’s just asking for speed loss.
     
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  4. Prozach2

    Prozach2 Workshop Leader

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    Here's how I do it: The rear wheels are drilled at a 3 degree angle. The axles are straight and pointing up at 12:00. The axle hole for the FDW is drilled in straight at 0 degrees, and the axle is bent down at 3 degrees. It's pointing down at 6:00. The wheel opposite the FDW goes in at 0 degrees and has a straight axle. This wheel is raised off the track by the FDW's bent axle. The FDW axle is turned slightly to accomplish the desired steer. However, I'd never turn that axle so much that it wasn't pointing down. I guess that bent axle would keep pointing down to between 5:00 and 7:00ish depending on what was needed to accomplish the desired steer. Some people raise the axle opposite of the FDW. Others just rely on the bend of the FDW axle to lift the other wheel off the track. I guess it just depends on how thin you're trying to get that car. I saw a picture of a car the other day where it looked like they hadn't even drilled a hole for the raised wheel. It looked like they just taped the axle to the top of the car and then put vinyl over it.

    FYI - I'm no expert. I'm writing this partially to be helpful and partially so someone will chime in if I'm wrong! :D
     
    Last edited: Feb 11, 2021
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  5. T-Bone Racing

    T-Bone Racing District Champion

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    I don’t see a problem with that. Everything you said is spot on!
     
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  6. CastleCrasher

    CastleCrasher Pinewood Ninja

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    Thank you for the break down though I was familiar with the rest lol. It's just that I never saw/heard anyone ever say what direction to point the bent head. So with nothing else to go on, logic told me upward would make the wheel run on the head. So that's what I've done for about 9 cars over the last 3 years, making a pack champion the first 2 of 3.
     
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  7. Eric Scheid

    Eric Scheid Pack Champion

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    I used to think this too (up vs down) until I saw some elite level cars. I turned one of my cars the other way (down vs up) and once the sweet was found I saw a noticeable reduction in friction. In a basic role down a slight incline on a test track the difference in free rolling distance was remarkable. My suspicion is that it just easier to get a good polish on the resulting interface axle inner bore than it is on the outer hub and nail head. The contact area is potentially smaller too. I agree that the wheel moves towards the nail head (angular momentum) presuming a right side FDW as it moves but it is moving away from the worst friction interface rather than getting forced into it.

    The contact with the rail could be improved too. The positive camber reduces the amount of sideways travel in the front. Sure you might find an angle where you are pinching the track but when you find the right spot, all time moving forward is better than sideways.

    If this is totally off please correct me. Thanks
     
    Last edited: Feb 11, 2021
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  8. CastleCrasher

    CastleCrasher Pinewood Ninja

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    Made sense to me. Somehow the way you explained it helped click it all together in my head (so hopefully you're correct lol)
     
  9. Mojo Racing

    Mojo Racing National Contender Pro Racer

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    The main reason that the axle is turned down is because of the spot where the wheel contacts the track. If it is rotated up, you will have the leading edge of the wheel in contact with the track, causing a downward friction. If you have it turned down, you will be contacting the track with the bottom of the wheel, while it is rolling forward, causing less friction.

    Up still gives you steer and stability, but down gives you steer, stability, and speed.
     
  10. CastleCrasher

    CastleCrasher Pinewood Ninja

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    Thanks Mojo. All that geometry involved never occurred to me but makes perfect sense.
     

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