Non-rising NRV tool, source yet?

Discussion in 'Fettling Forum' started by hikerduane, Feb 14, 2020.

  1. hikerduane

    hikerduane Subscriber

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    I know some have no idea or think it is simple to concoct one in 30 minutes, a cheap NRV tool that can be locked down into place, so when force is applied to unscrew a very stubborn NRV, it won't ride off of the NRV or round the head. For me, the two issues are making a close to precise slot to engage the NRV head and getting the upper part of the tool shaft to take the torque required to "snap" the NRV loose, since if using a drilled out spare pump tube cap, makes trimming down the tool shaft enough so that there is still some material left on it to not twist and break after all the work. I've seen a few examples, one was very nice and robust, saw one made from a hardened steel bolt with a round chunk of steel brazed on the end with a slot cut in it, but that would need the upper portion trimmed down so some sort of cap could go over the shaft and screw onto the pump tube, with some flats cut into it to allow a spanner to engage it or a adjustable wrench. Anyone up to the task yet? Has been years that some of us have been wanting something.
    Sorry if you have no idea of issues with NRV's, I have a large collection of Primus 96 stoves and it pains me to have to resort to unsoldering a pump tube to access the NRV.
    Duane
     
  2. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @hikerduane
    What has worked consistently well for me for years now is a Primus-branded NRV removal tool held vertically in a vice and I turn the fuel tank on that.

    Contributing to the effectiveness is that the Primus tool is a precision fit and the ‘slot’ is NRV head-shaped, so once it’s engaged with the NRV there’s no sideways movement or ‘camming-out’. The metallurgy of the tool is excellent too, high-carbon steel properly hardened and tempered, so it’s never degraded.

    Turning the tank on the fixed tool enables me to better judge and maintain downward pressure and apply sufficient torque.

    If the NRV head has been moderately mangled by a previous owner the technique still works. Too mangled, out comes the pump.

    I know that doesn’t address the ‘non-rising tool’ (!!!) Duane but though lower tech it’s a work-around that’s not made me hanker for something better.

    John
     
    Last edited: Feb 14, 2020
  3. hikerduane

    hikerduane Subscriber

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    I have a good selection of tools, one or the other usually work. The Primus 96's have the most issues as they don't have a lead washer under the top piece. I've done what you mention, the tool still slipping or rising off. I've dented a couple trying to wedge between the ends of a vise. Some are quite stuck.
    Duane
     
  4. Afterburner

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    Sorry, not yet up to the task...:cry:

    I have been thinking to make that kind of NRV tool for couple of years. I have machines and recently got a workshop for them. Now I am putting machines into working condition but it will take some time to get them all into running condition. Lathes are almost ok... I am working with collet draw bars and small chuck draw bars. Once they are ok lathes are done.

    Milling machine(old and used) that I bough needs a full clean out and service. Also I need to learn to use it. Never used one before. :lol::oops:

    Cutter grinder is ok, but I need to make work piece holders for it and modify work piece holders that I have for other brand cutter grinder. Also this kind of machine I have never used before. :lol::doh::oops:

    I have been thinking about NRV tool set that would have one twisting handle that would fit into various size 'NRV sockets' for different size pump tubes and NRVs. Maybe I first need to make one test piece for #5 size to see how planned concept would work. Locking down for different size pump tubes & NRV and fitting into common twisting handle is a bit challenge to do, but maybe there is some solution for it. :-k:doh:
     
  5. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Here is a link to a post of the design and construction of a clever and relatively “simple” NRV removal tool:

    Making a special key for NRV removal

    Best Regards,
    Kerophile.
     
  6. snwcmpr

    snwcmpr Subscriber

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    If you know that there is not a lead washer, then penetrating oil should work a lot better. The washer has appeared to be an inhibitor to the penetrating of the penetrating oil.
     
  7. BradB

    BradB United States Subscriber

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    807E6894-5E3A-4AE6-B143-2C4B3FC69B30.jpeg 0D96FD4B-3979-4616-9884-40ED890ECA24.jpeg Unfortunately this beautifully made tool seems to no longer be available. Although not the lock down type, it has not failed me yet. However, I have no 96 stoves to test it on.
     
  8. Majicwrench

    Majicwrench Subscriber

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    I like the one in the link above (thanks Kerophile) and that is pretty much what I had in mind.
     
  9. hikerduane

    hikerduane Subscriber

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    I'm thinking this isn't much of an issue for people as they may only have a stove here and there of many different sizes, brands. I have a number of different types of tools, even a couple of Stu's early models that I have mostly used. 20% of my collection are Primus 96 stoves, so I have a need and have had many that had a stubborn NRV. No new news.
    Duane
     
  10. snwcmpr

    snwcmpr Subscriber

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    While waiting you can add some penetrating oil. :)
     
  11. abbahco1

    abbahco1 Subscriber

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    This is an excellent tool - it has removed even the most recalcitrant NRVs...
     
  12. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @hikerduane
    Just to recap for any machinists willing to take up your challenge Duane, the relevant tool is Primus part number 1596 (from a 1937 Finnish catalogue, Stove Reference Library HERE.)

    DE0456BE-24A7-4737-8F6F-6B5769DA2B4C.jpeg

    The collar on the shaft will be fixed at a position where when the head of the tool is engaged with the NRV and the pump cap is screwed down the collar butts up to the underside of the cap, preventing the ‘business end’ from lifting off the NRV head. Not a ‘universal’ tool, there’d have to be a version for varying stove bores and lengths.

    As I said earlier in this thread, the slender proportions of Primus NRV tools require quality high-carbon steel, suitably hardened and tempered, in order not to snap, or corkscrew, or have the tool head degrade after a few tussles with NRV’s.

    John
     
    Last edited: Feb 16, 2020
  13. snwcmpr

    snwcmpr Subscriber

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    Which tool is that?
     
  14. hikerduane

    hikerduane Subscriber

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    The slender shaft has concerned me too. That tool is real simple. Messed with pieces yesterday, may ask at the parts houses in town for help, they don't act real helpful for a small sale.
    Duane
     
  15. snwcmpr

    snwcmpr Subscriber

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    It is not going to be easy to find people interested in this hobby. And less so with the enthusiasm that you have Duane.

    Ken
     
  16. JP2

    JP2 Subscriber

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  17. hikerduane

    hikerduane Subscriber

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    @JP2, I"ve seen similar online using a long, threaded bolt, but may not find one threaded the whole way, could then just notch the head to accept the NRV head without adding a pipe sleeve, would still be centered. But that would be a weak point I have found out, tried to thread a nut over the cut but that wasn't working. I can see in the link that the double nutted, reinforced rod where the bar passes thru strengthens that area and eliminates making flats to engage a wrench.
    Duane
     
  18. JP2

    JP2 Subscriber

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    @hikerduane
    Ok, what I like about this technique is that the modified nut at the bottom of the pump is push down and hold the rod tight on the NRV when you unscrew it. Only the rod do the job. Also your don't scratch the wall tube.
    DSC07737.JPG
     
  19. hikerduane

    hikerduane Subscriber

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    Not sure, but I think that won't work on the slender pump tube on my 96's, the nut at the bottom has to be ground too much and the NRV head requires a wider slot. I may try making a slot in threaded stock and sliding a piece of pipe over it. I saw one online that had a round chunk of metal on the end of a bolt or threaded rod with a slot side to side, the metal keeping the tool centered.
    Duane
     
  20. Twoberth

    Twoberth United Kingdom Subscriber

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    Duane, just scale everything down to make a separate NRV removal tool for your 96s.

    The design is exactly the same. My regular (dirty) 2 pint removal tool is on the left, and the one for 96s on the right.

    DSC09447.JPG
    In the latter case I didn't grind down a nut, I fitted a tight steel sleeve over the threads after cutting the NRV slot. Then I crimped it in place with mole grips.

    DSC09448.JPG
    From memory the 96 tool is made from 7/16" threaded bar.