Long nut or std w/lock ring for Fuji DPS?

Discussion in 'Rods and Rod Blanks' started by putter, Oct 10, 2020.

  1. putter

    putter Active Member

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    Wondering which set-up provides a stronger hold and stays locked down better:

    1. DPS-LD (Long nut)
    2. DPSSD (Standard nut) with Lock Ring

    On the rods I previously built with the DPS-LD, I've had the screw nut back-off during fights. I don't think this is supposed to happen so perhaps I'm not twisting tight enough? Having primarily used Alps Centra-Lock seats I'm afraid of stripping the threads if I tighten with a similar amount of pressure.

    Unfortunately, I don't have anything with the Standard nut to compare. Also, I'm using the seats with conventional reels in the unlikely event it makes a difference. Would appreciate any insight.

    PS - it's not possible to have a lock ring with the Long-nut because the reel foot opening gets too small, even with a spacer (which is dang hard to get in the USA).
     
  2. hafnor

    hafnor Senior Member

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    I never had any issue with regular nut and lock ring. I always use a tiny strip of black electrical tape on the reel foot so it sits snug inside its "housing"
     
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  3. putter

    putter Active Member

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    hafnor, as your experience shows, there seem to be very few issues with genuine Fuji DPS products.

    However, my question pertains to which setup provides the strongest hold. I think I've found my answer from a website discussing a rule of thumb for "thread engagement" (how much the height of threads of the screw are engaged) of nuts/bolts.

    I presume the rule of thumb principles apply here as well. It describes thread engagement as having two factors: length of thread engagement and percentage of thread engagement. Simply put, more thread engagement can result in higher tensile strength a joint. If a bolt is longer than needed to develop full tensile strength in a nut member, that excess material is wasted. On the flip side, if there is not enough bolt length engaged in a nut member, the bolt has a higher probability of stripping out before full tensile strength capability is achieved.

    Not considering manufacturing tolerances, both the long and standard DPS nuts share the same thread pitch and height. Since the long DPS nut can capture more than twice the "bolt length" of the standard DPS nut, it should have more than twice the thread engagement. The long DPS should therefore provide much higher tensile strength and less likelihood of stripped threads. The Fuji lock-nut system may still be more resistant to backing-off due to mechanical design, but I think the long nut should be significantly more resistant to backing-off than the standard nut alone, if tightened properly.
     
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  4. hafnor

    hafnor Senior Member

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    sounds sound @putter ;) bigger surface area in contact makes for a stronger connection.
     
    putter likes this.
  5. Boston Tangler

    Boston Tangler Site Sponsor

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    Long Nut would be my vote its ashame you can't use both the long nut and the locking nut together tried it doesn't work unless Fuji where to offer a longer neck on the reel seat itself
     
    putter likes this.
  6. putter

    putter Active Member

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    ^^ +1.

    Dan, have you considered selling the Fuji Long Nut seat and parts?
     
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  7. Boston Tangler

    Boston Tangler Site Sponsor

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    Fuji tends to stock/distribute in boxes of 20/25/50. As long as I take a full box the rod factory has offered to sell me any/all Fuji parts I want. This could cut a full 2 layers off the prices too

    Palmarius Popping 80H 00021.jpg
     
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  8. putter

    putter Active Member

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    Yup, would be fantastic for us here Stateside!
     
  9. putter

    putter Active Member

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    Exactly. Run out of thread with the LD nut. After screwing down tight, there are no threads left for a lock-nut to fit.