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Unusual 1/4-18 tap
Going through some old taps I found a tap marked 1/4"-18. I know that is the
designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young |
Unusual 1/4-18 tap
On Jan 11, 7:28 pm, "Don Young" wrote:
Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young A quick Goggle search turned up a web site listing 1/4-18 straight pipe tap (NPS) using a 29/64 drill bit for the hole. So, I guess it is a regular size tap, just for a little used application. Years ago, I had to turn some pipe fittings for a vacuum pump my late business partner was going to use in his chemistry lab. The threads were like yours, except about 3/4 as I recall. Same thread as 3/4 pipe, but no taper. The fittings sealed flush to the top of the pump. Taper was not used for sealing. Maybe your tap was for something similar. Paul in Central Oregon |
Unusual 1/4-18 tap
I have a delightful table together by Andy Pugh of Bodgesoc Industries,
Sheffield, UK showing 526 standard thread sizes up to 6" . Closest it comes to yours is a 16-18 ASME Thread with .268" OD and 18 threads Don Young wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young |
Unusual 1/4-18 tap
Don Young wrote:
Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young Had a look in a cat and 16, 18, 20, 22, 24, 26, 27, 28, 30 and 32 tpi taps in 1/4" size, were in common supply, once. Tom |
Unusual 1/4-18 tap
"RoyJ" wrote in message ... I have a delightful table together by Andy Pugh of Bodgesoc Industries, Sheffield, UK showing 526 standard thread sizes up to 6" . Closest it comes to yours is a 16-18 ASME Thread with .268" OD and 18 threads Don Young wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young 1/4 - 18 is a NPS (National Pipe Straight) standard size. -- Ed Huntress |
Unusual 1/4-18 tap
On Fri, 11 Jan 2008 20:07:11 -0800 (PST), "
wrote: On Jan 11, 7:28 pm, "Don Young" wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young A quick Goggle search turned up a web site listing 1/4-18 straight pipe tap (NPS) using a 29/64 drill bit for the hole. So, I guess it is a regular size tap, just for a little used application. Years ago, I had to turn some pipe fittings for a vacuum pump my late business partner was going to use in his chemistry lab. The threads were like yours, except about 3/4 as I recall. Same thread as 3/4 pipe, but no taper. The fittings sealed flush to the top of the pump. Taper was not used for sealing. Maybe your tap was for something similar. Paul in Central Oregon Apparently McMaster Carr carries them. They were used on some old machinery, apparently - as well as on some thermocouple applications. I think it is also used on some electronics devices - the thread on some control stems (potentiometers) is 18 TPI from what I remember - I know neither UNC or UNF nuts fit, and nor do metric standards. -- Posted via a free Usenet account from http://www.teranews.com |
Unusual 1/4-18 tap
On Fri, 11 Jan 2008 20:07:11 -0800 (PST), "
wrote: On Jan 11, 7:28 pm, "Don Young" wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young A quick Goggle search turned up a web site listing 1/4-18 straight pipe tap (NPS) using a 29/64 drill bit for the hole. So, I guess it is a regular size tap, just for a little used application. Years ago, I had to turn some pipe fittings for a vacuum pump my late business partner was going to use in his chemistry lab. The threads were like yours, except about 3/4 as I recall. Same thread as 3/4 pipe, but no taper. The fittings sealed flush to the top of the pump. Taper was not used for sealing. Maybe your tap was for something similar. Paul in Central Oregon Some thermocouple fittings are 18tpi and fit a 1/4" hole. -- Posted via a free Usenet account from http://www.teranews.com |
Unusual 1/4-18 tap
Ed Huntress wrote:
"RoyJ" wrote in message ... I have a delightful table together by Andy Pugh of Bodgesoc Industries, Sheffield, UK showing 526 standard thread sizes up to 6" . Closest it comes to yours is a 16-18 ASME Thread with .268" OD and 18 threads Don Young wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young 1/4 - 18 is a NPS (National Pipe Straight) standard size. -- Ed Huntress Hardly, in the case of NPS, 1/4 refers to the nominal bore of the pipe, the od is .540, whereas this tap has a diameter of 1/4" Tom |
Unusual 1/4-18 tap
"Tom" wrote in message ... Ed Huntress wrote: "RoyJ" wrote in message ... I have a delightful table together by Andy Pugh of Bodgesoc Industries, Sheffield, UK showing 526 standard thread sizes up to 6" . Closest it comes to yours is a 16-18 ASME Thread with .268" OD and 18 threads Don Young wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young 1/4 - 18 is a NPS (National Pipe Straight) standard size. -- Ed Huntress Hardly, in the case of NPS, 1/4 refers to the nominal bore of the pipe, the od is .540, whereas this tap has a diameter of 1/4" Tom Ah, I read the post too quickly. Thanks for the correction. -- Ed Huntress |
Unusual 1/4-18 tap
Ed, not if the tap diameter is 1/4 inch.
Steve "Ed Huntress" wrote in message ... "RoyJ" wrote in message ... I have a delightful table together by Andy Pugh of Bodgesoc Industries, Sheffield, UK showing 526 standard thread sizes up to 6" . Closest it comes to yours is a 16-18 ASME Thread with .268" OD and 18 threads Don Young wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young 1/4 - 18 is a NPS (National Pipe Straight) standard size. -- Ed Huntress |
Unusual 1/4-18 tap
Tom,
They are still available, but usually special order. Steve "Tom" wrote in message ... Don Young wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young Had a look in a cat and 16, 18, 20, 22, 24, 26, 27, 28, 30 and 32 tpi taps in 1/4" size, were in common supply, once. Tom |
Unusual 1/4-18 tap
clare at snyder.on.ca wrote:
I think it is also used on some electronics devices - the thread on some control stems (potentiometers) is 18 TPI from what I remember - I know neither UNC or UNF nuts fit, and nor do metric standards. I worked in the electronic field for nearly 60 years and never saw a potentiometer with a coarse thread. The 3/8 ones were 32 and the "modern" 1/4 are 40. The damn metric ones I don't know about. :-) ...lew... |
Unusual 1/4-18 tap
On Jan 12, 7:48 am, Lew Hartswick wrote:
clare at snyder.on.ca wrote: I think it is also used on some electronics devices - the thread on some control stems (potentiometers) is 18 TPI from what I remember - I know neither UNC or UNF nuts fit, and nor do metric standards. I worked in the electronic field for nearly 60 years and never saw a potentiometer with a coarse thread. The 3/8 ones were 32 and the "modern" 1/4 are 40. The damn metric ones I don't know about. :-) ...lew... A few months ago I had to make some custom mountings for potentiometers and encoders, and I had to buy a special 3/8"-32 tap for the stem. It was aweful to tap since it was so large but such a fine thread. Took me 4 tries to get it right. |
Unusual 1/4-18 tap
" wrote in message ... On Jan 11, 7:28 pm, "Don Young" wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young A quick Goggle search turned up a web site listing 1/4-18 straight pipe tap (NPS) using a 29/64 drill bit for the hole. So, I guess it is a regular size tap, just for a little used application. Years ago, I had to turn some pipe fittings for a vacuum pump my late business partner was going to use in his chemistry lab. The threads were like yours, except about 3/4 as I recall. Same thread as 3/4 pipe, but no taper. The fittings sealed flush to the top of the pump. Taper was not used for sealing. Maybe your tap was for something similar. Paul in Central Oregon Pipe threads are not to be confused with other types of threads, be they straight or tapered. They are unique to pipe, and pipe alone. A 1/4" pipe has an OD of .540", far greater than the tap in question. Note that the tap drill size you mentioned (29/64") is .453", much larger than the major diameter of the tap in question. Harold |
Unusual 1/4-18 tap
"Ed Huntress" wrote in message ... "RoyJ" wrote in message ... I have a delightful table together by Andy Pugh of Bodgesoc Industries, Sheffield, UK showing 526 standard thread sizes up to 6" . Closest it comes to yours is a 16-18 ASME Thread with .268" OD and 18 threads Don Young wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young 1/4 - 18 is a NPS (National Pipe Straight) standard size. -- Ed Huntress But not in this case. Harold |
Unusual 1/4-18 tap
"Steve Lusardi" wrote in message ... Tom, They are still available, but usually special order. Steve "Tom" wrote in message ... Don Young wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young Had a look in a cat and 16, 18, 20, 22, 24, 26, 27, 28, 30 and 32 tpi taps in 1/4" size, were in common supply, once. Tom Thanks to everybody for the information. If anyone ever needs such a tap, you know where to borrow one!! I did notice that it had "CARD" on it so that is probably the manufacturer. Don Young |
Unusual 1/4-18 tap
On Fri, 11 Jan 2008 21:28:50 -0600, "Don Young"
wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot |
Unusual 1/4-18 tap
Stealth Pilot wrote:
On Fri, 11 Jan 2008 21:28:50 -0600, "Don Young" wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot I hope you read you pilot notes with greater concentration than you did the original post? :-) Tom |
Unusual 1/4-18 tap
On Mon, 14 Jan 2008 05:56:18 +1300, Tom
wrote: Stealth Pilot wrote: On Fri, 11 Jan 2008 21:28:50 -0600, "Don Young" wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot I hope you read you pilot notes with greater concentration than you did the original post? :-) Tom Got me a left hand thread nut off a dead 1/2 inch arbor and decided to make me an arbor to fit the other end of the 1/4 HP, double shaft motor. Started to cut the threads when something told me to verify that I had everything set correctly, oh-oh, I'm cutting 20 tpi and the nut is 24 tpi. Fortunately I had only done one pass; my arbor has a funny thread every fifth one. Gerry :-)} London, Canada |
Unusual 1/4-18 tap
Stealth Pilot wrote:
On Fri, 11 Jan 2008 21:28:50 -0600, "Don Young" wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot The way I learned it the "F" stood for "fuel". Things like gasoline would disolve many of the old dopes used to seal NPT threads and allow a "spiral leak" along the threads. The male and female tapered dryseal thread forms are designed to make a liquid tight metal to metal seal when tightened. I've never heard of an NPSF (straight) dryseal thread and it's sort of hard to see how it could work, nor did Google help me find one. Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) The speed of light is 1.98*10^14 fathoms per fortnight. |
Unusual 1/4-18 tap
Jeff Wisnia writes:
I've never heard of an NPSF (straight) dryseal thread and it's sort of hard to see how it could work, nor did Google help me find one. NPSF is "Dryseal USA (American) Standard Fuel Internal Straight Pipe Thread" according to _Machinery's Handbook_. |
Unusual 1/4-18 tap
On Mon, 14 Jan 2008 05:56:18 +1300, Tom
wrote: Stealth Pilot wrote: On Fri, 11 Jan 2008 21:28:50 -0600, "Don Young" wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot I hope you read you pilot notes with greater concentration than you did the original post? :-) Tom why what's the problem? I read the details from my mullins thread wall chart. it lists the 18 pitch threads exactly as quoted. the post answers the last two sentences of the question. a. what's it used for? - pipe thread. b. his suspicion that it was a mistake is probably wrong since there is a listed application for the thread size. pilot notes .....pilot notes??? now what are they? a description of the machining standards for slocumbe drills? Stealth :-) Pilot |
Unusual 1/4-18 tap
"Stealth Pilot" wrote in message ... On Mon, 14 Jan 2008 05:56:18 +1300, Tom wrote: Stealth Pilot wrote: On Fri, 11 Jan 2008 21:28:50 -0600, "Don Young" wrote: Going through some old taps I found a tap marked 1/4"-18. I know that is the designation for a standard NPT tap but this tap is actually 1/4" in diameter. Looks like a 1/4"-20 with coarser threads. Does anyone know of an application for such a thread? I suspect it might have been made mistakenly from a list of sizes which included the pipe thread. No manufacturer identification and appears to be a cheap import quality. Don Young a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot I hope you read you pilot notes with greater concentration than you did the original post? :-) Tom why what's the problem? I read the details from my mullins thread wall chart. it lists the 18 pitch threads exactly as quoted. the post answers the last two sentences of the question. a. what's it used for? - pipe thread. b. his suspicion that it was a mistake is probably wrong since there is a listed application for the thread size. pilot notes .....pilot notes??? now what are they? a description of the machining standards for slocumbe drills? Stealth :-) Pilot You missed the fact that this thread in question is 1/4" diameter. It is *not* a pipe thread. It is a non-standard 1/4" tap. Harold |
Unusual 1/4-18 tap
On 2008-01-14, Stealth Pilot wrote:
On Mon, 14 Jan 2008 05:56:18 +1300, Tom wrote: Stealth Pilot wrote: [ ... ] a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot I hope you read you pilot notes with greater concentration than you did the original post? :-) [ ... ] why what's the problem? I read the details from my mullins thread wall chart. it lists the 18 pitch threads exactly as quoted. Out of curiosity -- what does the mullins thread wall chart say is the OD of the thread. IIRC, the original question said that the actual measured OD was 1/4", while any pipe thread would normally be named for something closer to the bore size, thus requiring a much larger diameter for the threaded part. the post answers the last two sentences of the question. a. what's it used for? - pipe thread. Not clear -- until you can tell us that your chart shows the OD as 1/4". It could easily be some other thread with the same pitch, but a smaller OD, for a different function. b. his suspicion that it was a mistake is probably wrong since there is a listed application for the thread size. Again -- are you sure about the OD? Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
Unusual 1/4-18 tap
On 15 Jan 2008 04:58:17 GMT, "DoN. Nichols"
wrote: On 2008-01-14, Stealth Pilot wrote: On Mon, 14 Jan 2008 05:56:18 +1300, Tom wrote: Stealth Pilot wrote: [ ... ] a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot I hope you read you pilot notes with greater concentration than you did the original post? :-) [ ... ] why what's the problem? I read the details from my mullins thread wall chart. it lists the 18 pitch threads exactly as quoted. Out of curiosity -- what does the mullins thread wall chart say is the OD of the thread. IIRC, the original question said that the actual measured OD was 1/4", while any pipe thread would normally be named for something closer to the bore size, thus requiring a much larger diameter for the threaded part. the post answers the last two sentences of the question. a. what's it used for? - pipe thread. Not clear -- until you can tell us that your chart shows the OD as 1/4". It could easily be some other thread with the same pitch, but a smaller OD, for a different function. b. his suspicion that it was a mistake is probably wrong since there is a listed application for the thread size. Again -- are you sure about the OD? Enjoy, DoN. I wonder what that glow is around here? 11mm tapping drill for both. oh I get it. the light's on. Stealth Pilot |
Unusual 1/4-18 tap
Stealth Pilot wrote:
On 15 Jan 2008 04:58:17 GMT, "DoN. Nichols" wrote: On 2008-01-14, Stealth Pilot wrote: On Mon, 14 Jan 2008 05:56:18 +1300, Tom wrote: Stealth Pilot wrote: [ ... ] a 1/4 x 18 straight thread is NPSF (straight) DRYSEAL ...whatever that means in english. it is a pipe thread. in a taper that thread would be NPTF (taper) DRYSEAL. Stealth Pilot I hope you read you pilot notes with greater concentration than you did the original post? :-) [ ... ] why what's the problem? I read the details from my mullins thread wall chart. it lists the 18 pitch threads exactly as quoted. Out of curiosity -- what does the mullins thread wall chart say is the OD of the thread. IIRC, the original question said that the actual measured OD was 1/4", while any pipe thread would normally be named for something closer to the bore size, thus requiring a much larger diameter for the threaded part. the post answers the last two sentences of the question. a. what's it used for? - pipe thread. Not clear -- until you can tell us that your chart shows the OD as 1/4". It could easily be some other thread with the same pitch, but a smaller OD, for a different function. b. his suspicion that it was a mistake is probably wrong since there is a listed application for the thread size. Again -- are you sure about the OD? Enjoy, DoN. I wonder what that glow is around here? 11mm tapping drill for both. oh I get it. the light's on. Stealth Pilot What is it about the following that you are unable of grasp?: From the OP: "I know that is the designation for a standard NPT tap, but this tap is actually 1/4" in diameter." Tom |
Unusual 1/4-18 tap
On 2008-01-15, Stealth Pilot wrote:
On 15 Jan 2008 04:58:17 GMT, "DoN. Nichols" wrote: On 2008-01-14, Stealth Pilot wrote: [ ... ] why what's the problem? I read the details from my mullins thread wall chart. it lists the 18 pitch threads exactly as quoted. Out of curiosity -- what does the mullins thread wall chart say is the OD of the thread. IIRC, the original question said that the actual measured OD was 1/4", while any pipe thread would normally be named for something closer to the bore size, thus requiring a much larger diameter for the threaded part. the post answers the last two sentences of the question. a. what's it used for? - pipe thread. Not clear -- until you can tell us that your chart shows the OD as 1/4". It could easily be some other thread with the same pitch, but a smaller OD, for a different function. b. his suspicion that it was a mistake is probably wrong since there is a listed application for the thread size. Again -- are you sure about the OD? [ ... ] I wonder what that glow is around here? 11mm tapping drill for both. 11mm divided by 25.4 mm per inch gives a diameter of 0.4331", and the actual tap diameter would have to be a bit over the tap drill size, while the original poster said that *his* tap was measured at 1/4" (that is 0.250" so these are *very* different taps. oh I get it. the light's on. Where? Not in your head, yet, apparently. Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
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