I received my order from Juliands. NRV's are like in the picture that Ken sent. Thread is missing the chamfer. Maybe I try to fix them by turning or with fine file. Then I can try how thread works. Price was so low that extra work can be justified...
I'll do... Major diameter of the thread seems to be 7,9mm so at least that looks good. Edit: Also I try to check how jets that came with NRV's will work.
package arrived, havn't had a chance to do a fettle , but will be extremely interested in finding out if these inexpensive parts are worth a dang buzz
I wish to keep this thread alive. Is the issue all NRVs, some NRVs, or is it just the leading thread needing chamfer? There are too many varying statements in this thread to get a clear conclusion. Is the seller mentioned selling mis-made parts, or is it simply that a step in production, deburring & chamfer, was neglected to reduce the cost? Ken in NC
I did research for NRV's but forgot to post results... I used a microscope that has 60º angle screen inside the ocular and table has X-Y moving capability and knobs to move the table. X-Y moving knobs are having micrometer scale. (Something like this http://www.ebay.com/itm/Used-Nikon-MM-11B-Measurement-Microscope-/400294190330 but table moving knobs are like mega size micrometer vernier knobs) I have two adapters to mount DSLR into microscope but both of them were different size than in microscope. I haven't had time to make adapter ring so no photos from the measurements. I had original Primus(stamped on NRV) NRV from un-used and un-opened Swedish Defence surplus Optimus 200 lantern spare kit. So that NRV should be perfect NRV to be a reference. With microscope and it's X-Y table I got results: -thread angle 60º -thread shape perfect triangles on outer and inner sides of thread -pitch 0,73 mm -outer diameter 8 mm NRV's that are pictured in this thread: https://classiccampstoves.com/threads/29203 -thread angle 60º -thread shape non perfect triangles on outer side of thread -thread shape non perfect triangles on inner side of thread -pitch 0,70 mm -outer diameter 8 mm NRV's that I received from Juliands: -thread angle 60º -thread shape perfect triangles on outer sides of thread -non perfect triangles on inner sides of thread -pitch 0,75 mm -outer diameter 8 mm (Both later NRV's thread triangles are missing the sharp tip. Tip of the triangle is cut about 20-25 % lower position that sharp tip would be) Juliands NRV's work some how. 0,02 mm difference in pitch is not a big problem. When thread shape is not perfect NRV is difficult to screw in. If both sides of the thread are having un-perfect thread profile NRV is quite impossible to screw in. I plan to try to make new thread onto those NRV's with M8x0,75 die to see it they work after that more better. (Sorry for late return into this matter and for poor documentary without photos. Hopefully some one understands what I tried to explain... 8-[ )
AB, thank you so much for taking the time to post results. Just to be more clear.... What exactly do you mean by: -thread shape non perfect triangles on outer side of thread -thread shape non perfect triangles on inner side of thread Could you mean that the cutting tool was not 'square' to the NRV? Gary (BD) sent me a few NRVs he cleaned up, but I have been distracted with chores and other 'spring time activities' my 'stove hobby' has been on a back burner. Thanks, Ken in NC
Ken, Sorry my English will not reach up to level that I would be able to explain differences in thread profiles clearly... That's why pictures would have been very useful, but as I mentioned DSLR to microscope adaptation would need additional parts that I don't have (yet ). Maybe this picture helps: Thread on left upper corner is thread that I mean with a thread with perfect thread profile. Thread on right upper corner is having a thread profile where triangles on top and bottom are missing part of their tip. (If you think that thread is line of triangles. Every second is laying on it's side and every second is staying on it's tip) If NRV thread on pump is like on upper left corner and it's is having same major diameter than NRV but NRV's thread profile is like on upper right corner it will not screw in. That is exactly same case as with first NRV's that I measured. NRV's from Juliands are a bit better since inner part(=minor diameter "side") of the thread is not perfect (profile wise). I don't know if this makes matter any more clearer... 8-[
... Very good explanation. It makes sense to me. This is the same issue that occurs with some of the Indian/Chinese manufactured burners. Some will fit "Primus" threads and some won't. My question is: does anyone have or know if a correct 'tap and die' for the primus burner thread, and/or the NRV?
Optimus and Primus had thread taps for burners and nipples: https://classiccampstoves.com/fusion/gallery/15/1297900230-041.jpg https://classiccampstoves.com/fusion/gallery/15/1221606006-038.jpg https://classiccampstoves.com/fusion/gallery/15/1246698142-041.jpg But maybe they are quite difficult to find nowadays. Gary once mentioned that he got custom taps/die made for him for the burner threads. Price was quite high he mentioned. M8x0,75 tap/die is closest that you can get easily for NRV. Tap/die that has 8 mm major diameter and 35 tpi pitch would be more better. Just for fun I need to look dimensions of different burner threads with that measurement microscope.
No apologies are necessary. I speak/write no Finnish. You have my utmost respect. I think the word is 'truncated'. The thread pitch and angles are correct, but the major and minor diameters are not, truncated. Ken in NC Reading this thread with great interest.
Took some time for me to get "system" ready for taking pictures about those NRV threads... Sorry for a bit bad quality photos. I didn't had a proper microscope adapter for my camera so used film era microscope hood in my camera. This was also first time that I took photos through the microscope so my technique is not well matured... Anyway I believe that despite of a bit poor photos the difference on thread profiles can be seen. This is original Primus NRV thread (NOS Primus NRV): Thread profile of an aftermarket NRV: In both OD and pitch are same. On aftermarket thread triangle is wider due to cut top and bottom. So it will be quite hard to turn it into NRV thread that is on pump tube. There was also aftermarket NRV's that had same difference on thread profile and also difference on pitch. I try to play more with these aftermarket NRV's when I have some spare time and i.e. test how turning the aftermarket NRV into M8x0,75 die will effect to the thread profile.
@Afterburner Thank you for your effort. I recently purchased 10 from a seller on that auction site. Burred holes and threads. Even after cleaning up the burrs the flats are too big/wide for any of my NRV tools. The flats are also Not Parallel. I have not had a need for one recently, so I cannot say if they work. I will make them work when I need to. Ken in NC
I did like was mentioned the last few months, took a used one I had and fitted with a new pip, had to stretch the spring some, but held after a few minutes of use. Would have liked to save the old cork pip. Duane
If in both cases the thread angle is 60° and the pitch is equal between female and male part and if only the "missing triangle peaks" in the male part are the issue it should be helpful to file them out with a triangle needle file (= 60°). Regards, Philipp
I imagine that the manufacturer made a LOT of these NRVs at once. I would guess a screw machine, but, it could be a CNC machining center. Thousands and thousands of these parts and the quality was probably checked as sample lots. Maybe only checked to fit the stoves made locally, at that time. Has anyone determined who made them? If the 'truncated' threads are the result of a worn single point thread cutting tool, then there would be quite a variation in the threads of multiple lots of parts. Some would be more truncated than others. Alternatively, it could be the result of a badly made threading die, and then would be similar across all batches of samples. The truncated OD will have less influence than the truncated minor diameter. Chasing with a proper threading die may be the way to go. I seem to remember someone discussing the thread features of the NEW STOVES being different than the VINTAGE STOVES. Ken in NC
@snwcmpr Maybe you are referring to my thoughts in this post https://classiccampstoves.com/threads/warning-nrv.29083/#post-297041 on page one in this thread?
Good thread indeed as I am fixing a few NRV at Opt. 111 now. I am a bit confused when it comes to the NRV (but still learning). The NRV on the pictures; Original NRV I have had for some years. Marked `Sweden`. Lead washer. Threads fit good in pump tube. No brass pip-holder. NRV works well. NRV recently bought from an army surplus. Marked `Sweden`. White `plastic` (?) washer. Threads fit good in pump tube. No brass pip-holder. Not tested. NRV bought from supplier in US (before I found them for sale in Norway). No marking. Lead washer. Threads did not fit in pump tube (I stopped nearly immediately thanks to this thread). Brass pip-holder. Questions; Does this mean that NRV marked `Sweden` is good for Opt 111 (made in Sweden)? If unmarked; be careful / they do not fit? How to know before ordering / buying? Should I be concerned (I mean years ahead) for the white plastic washer? Anyone knows if they are good? Will they be possible to remove after long time us What are the benefits of using a brass pip-holder?
