Tap Terminology: For Light Fixture Threaded Tube

[Chipps]

[jihe]

Here in Europe they are M10x1. Sounds like it would be within decent tolerance with your measurements.

[Paul Alciatore]

I need to order a tap for a light fixture threaded tube. I am talking about the common threaded tube that is used for holding the parts of lights together. In my case it is for making a nut to fit the short piece of this threaded tube that holds the glass cover on a ceiling fixture. This size of threaded tube is very common on light fixtures and lamps in the US. For clarity, here is a photo of the present, plastic nut and of a short length (1.5") of the tube.



The OD of the tube measures 0.380" with a +/- of about 0.005" or so. The TPI is 27. I am fairly sure it is a pipe thread, probably 1/8" nominal size and it is not tapered. But there are several and likely different 1/8 - 27, non tapered pipe threads. So I want to know which tap I should be looking for. NPS, NPSC, NPSM, NPSF, NPSL and probably more. Or will any of them work?

So far I have not been able to find any OD listed for the available taps, just the nominal pipe/tube sizes which are not even accurate IDs.