Guest BobD735 Posted October 10, 2010 Share Posted October 10, 2010 I'm trying to identify a thread used on a map light for my car. I've measured the O.D. of the 1/4" long threaded part, and calculated that the thread is: 11/16-28. The nearest match I can find is 11/16-24. Do I need a larger magnifying glass, or is 28 thds. per inch a special thread?Bob Link to comment Share on other sites More sharing options...
Guest trainguy Posted October 10, 2010 Share Posted October 10, 2010 Tuff to see in 1/4 " of thread.Suggest that you find a thread pitch gauge[a machinest tool]'That will tell you what the pitch is.Phil Link to comment Share on other sites More sharing options...
Guest BobD735 Posted October 10, 2010 Share Posted October 10, 2010 Hi,Thanks for your response. I'm trying to determine whether there is an 11/16-28 thread.Bob Link to comment Share on other sites More sharing options...
Guest cben09 Posted October 10, 2010 Share Posted October 10, 2010 Buy a 1/4" fine bolt at the hardware store,,,american fine is 28 tpi,,use as guage,,,Ben Link to comment Share on other sites More sharing options...
Guest cben09 Posted October 10, 2010 Share Posted October 10, 2010 p/s British fine [cei],,is 26 tpi,,,and American pipe is 27 tpi,,,Ben Link to comment Share on other sites More sharing options...
Guest BobD735 Posted October 10, 2010 Share Posted October 10, 2010 Hi,From the responses that I'm getting, I think I'm confusing everyone. I have a map light which has, an externally threadeded male end, which I believe to be an 11/16-28 thread. I need to extend the map light and plan to use an internaliy threaded sleeve. I am trying to determine if there is an 11/16-28 thread, so that I can buy the correct tap to thread the sleeve.Thank you,Bob Link to comment Share on other sites More sharing options...
Guest cben09 Posted October 10, 2010 Share Posted October 10, 2010 Wrong approach,,,make the "nut" on the lathe,,and thread the hole in the lathe,,,It's called single pointing a thread,,Should be a simple trade school job,,,,Do they have trade schools anymore ???,,Is this to put a metal dash item into a wood dash?? Can you counter bore the back side???another way,,MAKE a nut with a projection to go through the deep wood,,Fun,,Ben Link to comment Share on other sites More sharing options...
Guest cben09 Posted October 10, 2010 Share Posted October 10, 2010 If the sleeve is very thin,,it could come out of the chuck,,Dont use the motor on the lathe,,,better to turn the chuck by hand,,better control,,I made a BSA motorcycle piston into a lenz hood for my camera this way,one dark night,,a piece of electric 3.5"condit made the extension,,,all threaded 48tpi [thread per inch],,Cheers,,Ben Link to comment Share on other sites More sharing options...
Larry Schramm Posted October 11, 2010 Share Posted October 11, 2010 Do you have a picture of what you are trying to match? It would help a lot with a ruler next to it. Link to comment Share on other sites More sharing options...
Guest BobD735 Posted October 11, 2010 Share Posted October 11, 2010 Hi again,All I need is to make a simple sleeve about 1" long with an internal 11/16-28 thread (1/4" long)on one end. This will thread into an existing male 11/16-28 thread on a map light. The other end of sleeve with no threads, will slip over an existing map light base, whose outside diameter is also 11/16".I'm trying to find out if an 11/16-28 tap exists, as my lathe doesn't cut threads.I'm doing this because I couldn't find a map light for my '20 Chalmers, but I did have the original base. The map light that I did find is the same diameter as my base, but it's threaded, and I have to be able to separate the two parts for assembly/disassembly. I believe my sleeve idea will work, so now I need to find a machinist to cut me some threads.I really appreciate all of your inputs.Thank you,Bob Link to comment Share on other sites More sharing options...
Bhigdog Posted October 12, 2010 Share Posted October 12, 2010 (edited) Yes the 11/16- 28 tap does exist. Yes it is available from MSC Industrial Supply in both plug and bottoming taps. Yes it is expensive @ about $70. Yes they are on line. Or simply Google 11/16-28 tap and any number of suppliers will appear at a lot cheaper prices.........Bob Edited October 12, 2010 by Bhigdog (see edit history) Link to comment Share on other sites More sharing options...
Guest BobD735 Posted October 12, 2010 Share Posted October 12, 2010 Thanks Bob. That's exactly what I am looking for. I'll check the sources out.I really appreciate your help.Bob Link to comment Share on other sites More sharing options...
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