Cheap home-made (Twoberth-proof) NRV removal tool

Discussion in 'Fettling Forum' started by Twoberth, Mar 24, 2019.

  1. Twoberth

    Twoberth United Kingdom Subscriber

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    I have several old stove tanks with stuck NRVs that now have rounded off corners. This is caused by the well know problem of the NRV tools slipping off the flats and progressively deforming the corners. I have tried all sorts of NRV tools on these tanks (both homemade and bought) with no success. Up until now!

    This is a simple homemade NRV removal tool consisting of a threaded bar that locks onto the pump tube at one end, and locks onto the NRV at the other end. It has proved itself on these problem tanks, with all the NRVs now having been removed. Here is how to make one.

    You will need: length of threaded bar and 3 nuts, and old pump tube cap, a length of suitable metal tubing (plumbing pipe will do) and a small piece of round rod (for the locking pin).

    DSC07734.JPG

    Cut a slot in one end of the bar to fit the NRV flats. File/grind one of the nuts until it is round and fits into the pump tube, and then thread on to the slotted end of the bar.

    DSC07737.JPG

    This reinforces the end, and centralises the slot on the NRV.

    Cut the tubing to the correct length so that when placed as a sleeve on the threaded bar it is flush with the end of the pump tube.

    DSC07739.JPG DSC07740.JPG DSC07741.JPG

    Drill a larger hole in the pump tube cap so that it fits over the threaded bar.

    DSC07742.JPG

    Drill a hole for the locking pin in a suitable position on the threaded bar so that there is room for a nut on either side of the hole.

    To use the tool, fit the reinforced notched bar into the pump tube and locate fully onto the NRV. Fit sleeve over bar, and lock the assembly in place with pump tube cap. Thread the nuts on to the bar so that they trap the locking pin in place.

    DSC07743.JPG

    Then ‘unscrew’ the inner of the two nuts, which will lock on the pin and unscrew the whole assembly including the NRV.

    DSC07744.JPG DSC07745.JPG

    I was going to say it was idiot-proof, but its certainly Twoberth-proof which may be the same thing.

    DSC07746.JPG

    This is one of the offending NRVs, which could not be gripped using normal NRV tools.

    DSC07747.JPG
     
  2. Harder D. Soerensen

    Harder D. Soerensen Denmark Subscriber

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    Pure genious!

    Well done!
     
  3. Kero-Scene

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    Very impressive!
     
  4. Christer Carlsson

    Christer Carlsson Moderator SotM Winner

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    Simplicity at its best!
    Well done.:thumbup:
     
  5. Twoberth

    Twoberth United Kingdom Subscriber

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    Thanks. Just used it again on a Primus 5 NRV that was soaking in WD 40 over the weekend. When it came out there was no washer on it!
     
  6. Christer Carlsson

    Christer Carlsson Moderator SotM Winner

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    Those mounted without a washer are generally the worst to get out!
     
  7. JP2

    JP2 Subscriber

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    WoW
     
  8. The Warrior

    The Warrior United States Subscriber

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    Very cool man, looks simple enough to do. Have to find a spare cap though.
     
  9. Tony Press

    Tony Press Australia Subscriber

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  10. Optimust

    Optimust United Kingdom Subscriber

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    @ Twoberth.

    Well thought out, alignment from the pump tube cap, & the nut that shrouds
    the slot, plus the pipe sleeve, are all essential for a very good design. Thank you Twoberth, & Best regards. Optimust.
     
  11. Twoberth

    Twoberth United Kingdom Subscriber

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    Thanks all for the comments.

    @The Warrior
    There is no need to find a spare pump cap. As @Radler points out if you make the version below.