Today I decided to tackle a prolonged job, the removal of a stuck NRV in a 1931 nickled Primus 96. Initially I had tried to remove it with the invaluable tool Stu made up many years ago, one of my best investiments for stove country. But straightaway it was clear this tool had no grip whatsoever on the damaged NRV. In fact the tool corkscrewed out, no matter what pressure against it I could muster even with the proces upside down in a vice. The maddening thing was, that with Stu's tool I was able to tighten the NRV , so the valve was 'loose', albeit now tight even more. Luckily I thought of using left-hand extractors, an investment made many decades ago. This day might have been in a good sign, as I managed to unearth this set without much searching. However, a longish drill needed to be purchased to open up the existing passage in the stuck NRV, with a diameter suitable to offer proper purchase to the right size extractor. A pencil torch helped me to view the situation, and found the drillbit of suitable lenght. The hole was widened to what I thought a proper depth, and indeed I was able to jam the extractor in. I used a deep socket of small size that fitted snugly around the square end of the extractor, just enough to connect a small (1/4") tommy bar. Some effort went into torquing the extractor down, expecting this NRV to do 'pop' anytime, but not so. In fact I lost purchase, with the extractor's threads full of brass. Visions of having to remove the whole pump tube by flame came up, which for me would be a first. While having some experience, also with brazing, I cannot see myself as an artisan working on a small stove in nickle finish yet. So with little to lose, I drilled even deeper into the NRV, and again found grip with the extractor. With some apprehension I wrenched the tommey bar anti-clockwise, and to my relief the NRV now gave in with a snap. It took a pair of pliers to seperate the remnant of the NRV from the extractor so the full damage became clear in sight. Inside the left screw marks of the extractor can be seen in the soft brass. Outside the clear deformity of the once straight sided cam on the NRV that had turned into a wave-like protusion which had defeated a good quality tool. Today therefore was a good day, with a lingering job now brought to a happy ending. I should ad that, again, this NRV was fitted without a lead or fiber seal, something that seems to become a standard for pre-war stoves.
John (and CW), thank you, but let me be quick to replicate this skill thing, that happens to be one of your fortes imo. Especially the pump tube removal surgery, with little to no scars. I am still to learn that procedure, but I prefer not to, as yet. But I do have a batch of dented or otherwise lost-for-the-market victims to hone these skills on. Life is an ongoing lesson after all, and still much to discover. Mike
I've had no luck with a extractor, either takes metal off or is unable to get a purchase. I also have a couple of Stu's tools, but mostly rely now on a custom, non-rising NRV tool. Nothing better than to hear the snap of a NRV breaking loose. Most of my stuck NRV's have been with my Primus 96 collection. Duane
Duane, my confidence in these extractors is not too great either, for same reasons as you describe. But it was a situation in which I had little to loose, and I was plain lucky. Your non-rising tool is locked in with an end cap on the pump tube I presume - like Primus did offer at one time? Clearly Primus was aware of the risk to damage a brass NRV, but I found this original tool is not up to the really tough cases either, as the receptical of the cam on the NRV got easily damaged. But the principle is a good one, and should be applied with any unknown NRV to prevent damage For me, this means the vice approach, but sometimes you inherit or buy a mess in which everything fails. Such is life. Through the years you have mentioned your waxing collection of 96-es. What number do you have today, and what years are still to be found? Regards, Mike
Mike, I have 60 96's, I need two more years, looking for a "H" and a "AI". A few years I have multiples when I wasn't able to find out what the year was or was too quick to buy. A few nickel models thrown in also. I need to sell a few of my extras and some of my cannibalized founts. It's been interesting getting some NRV'S loosened, always looking for that snap. I've tried every which way like you to remove them. I'm not a neat resolderer so unsoldering a pump tube is my last resort. Duane
I do not believe that they could forsee an nrv sitting unchanged for decades. Without that tI cannot see them thinking that they needed to make such a robust tool.
You can never tell when these two models will enter your watch, but I will attache a note on my pinboard. I leave it up to you to ask assistance on this global forum, and perhaps this deserves an exclusive thread.. I think this is not your aim at all, but you are close to be listed in the Guinness book of Records imo. That is what I have been thinking: the tool works fine on (fairly) recent replaced NRV's. And by closing the tool up, there is little risk starting to deform the parallel cam on the valve. Mind, this particular removing tool is for the bigger size pump tubes, as in the model 100 or 221. Not sure if such a tool was available for the smaller diameter tubes that had varying lenghts as well (57 and 96)
Well then, good luck! With Britain the more likely place to find an 'H' - and likely not an AI, which could be found sooner in countries not economicly effected by the second world war. The 96 was a luxury item for most, I think.
I have exactly the same issue with an early Optimus 96 - and similarly am hoping to avoid having to unsolder the pump tube. @Dutchmike could you tell me what diameter drill bit you used? If possible I’d like to drill just the once to minimise chances of the nrw breaking off etc.
Rob, there is no particular size I could mention. You choose a drill size depending on what lefthand extractor you have, fit for the job. I copy what I wrote 3 years ago in above thread: "a longish drill needed to be purchased to open up the existing passage in the stuck NRV, with a diameter suitable to offer proper purchase to the right size extractor." By the way, there is nothing to fear of an eventual broken NRV. It will not worsen your problem. You will have a problem with drilling with too big a size drill that leaves too little material of the NRV that accepts the bite of the extractor without expanding, compounding the problem. If so, only a gradual increase of drill might give you a chance to create a very thin , bushing like tube, trying to avoid damaging the thread in the pump's bottom cap. A set of fine prying hooks could then be helpful to remove the remnants of the NRV. Patience is your most important tool, plus the abiltiy to 'visualise' what you are doing. Good luck, Mike
