Dears, I am (very) slowly mowing forward with my Coleman 249 fettle. Currently I need to fix threading on the generator nut. The nut is deformed at the end by numerous hits that it received. Maybe I will describe how and why I did it when lamp is ready, because the whole renovation process is getting more and more interesting Anyway, I consider buying proper tap to fix it or/and cut/file the last damaged 2mm of the nut. Nut seems to be approx. 0,5 inch size with 32 threads/inch. At least measuring tool with „32” number fits that threading the best. I will appreciate to provide the right tap/die size (@MYN ?)and maybe some other ideas how to fix the nut. All the best, Piotrek
1/2 - 32 UN (meaning straight, not tapered) is still a standard size but not very commonly used elsewhere compared to others. Taps and dies for that are available, but just not from the regular hardware stores across the street. That size is also used on some parts on the Coleman 236 and 237. ***Note: 1/2-32 tpi tapered is a special Coleman size, not the common UN series.
Thank you @MYN . That will be a challenge to find it in Poland (tried already yesterday on the Internet), but but we will see.
1/2-32UNS taps and dies seem to be somewhat easier to find in the USA than anywhere else. Some folks use thread restorer files like this for repairing threads instead.
1/2 - 32 UN set ordered already from US Amazon. I should get it in a couple of weeks. The funny thing is that I am not sure if I can restore the thread that easily anyway, because the nut is squeezed at the end and that will be hard to start new thread at the right spot to "meet and continue" undamaged thread located deeper. Maybe I will have to remove the most damaged part of the nut (file the whole nut end) to catch and start with tap at the right spot or to drill out that first 2mm of most damaged thread to continue with the tap. Interesting exercise is that little cute lamp for me, but better learn on 249 then something less common. I even had an idea to buy more taps&dies to have them just in case, but it seems that there are dozens of types not to mention sizes: Fastener Threading Specifications This is f.. ridiculous and I wonder if there is a tap collectors forum/community? Definitely the whole branch of knowledge and industry to learn... Thank you @MYN for support, because those toys from US are not that cheap at all... I will fix some Petromax in the meantime to relax
Besides ordering the uncommon taps, I believe you can also make one using a lathe and a vertical miller if you own or have access to these machines. A little troublesome but still possible if you are determined enough. Yes, there are simply too many types and sizes of different threads out there to collect. The specifications are also very detailed and have been stated in the numerous Standards. Fits and clearances for the specific application would need to be determined by the user too. There are many thread sizes that are not Standard and had been deliberate by the different manufacturers of lanterns and stove parts as well. Therefore, there are still a lot non-standard ones on these devices that cannot be ordered but have to be custome-made.
Thanks, Tony... I have managed to accumulate quite a few different sets of taps & dies including some rather odd sizes. The only taper tap I currently have is a 1/8 NPTF 27tpi... The F stands for fuel which makes sense. I've never used it yet as it needs a corresponding tapered reamer to expand the drilled hole into a conic section... I think!
Nice find Colin. As the taper is very slight - and if going into a short threaded part I suspect you would get away with a straight sided hole.
I might try if I had to, but I've had taps break on me before and it happens without warning. Also, the 1/8 NPTF is one of a kind... for me anyway so it would be a risk.
