¿ªÔÆÌåÓýOld flywheel style single cylinder gasoline farm engines mostly used 1/2" pipe threaded spark plugs. (Made after the low tention spark-points in the cylinder chamber, & before the high speed air cooled engines that became common after WWII) Tapered threads do not give a seal unless used with pipe dope or Teflon tape. (& other sealing methods I don't know about); Regular threading (no taper) up to a flange & gasket is the modern norm for spark plugs; the threads locate it, the flange & a gasket seals it. (& you can use dope/whatever on the threads to be really sure of a seal if you want.) I am not clear as to your need/use of tapered pipe threading...It is traditional for iron plumbing, cheap; & for installations that are semi-permenant, IE not have to be taken apart for a long time. Pipe thread taps & dies work with a straight pipe, both outside & inside size; IE no previous taper machining is needed. These taps & dies have their own built in taper, & will do the work themselves, albeit W/ a lot of effort, either by hand, or a pipe threading motor; but not a small lathe. Seems to me (here in Maine USA) that these threading procedures are better done by hand, with a die/ or tap, & only useing a lathe manually to mount/locate thease tools to get better accuracy. -----Original Message-----
>From: Roy >Sent: Nov 11, 2012 8:38 PM >To: 7x12minilathe@... >Subject: [7x12minilathe] Re: Aside from pipes and camera cable releases where else are tapered pipe threads used? > >With an OD of 5/16" it's 1/16" NPT. Both 1/16" & 1/8" NPT are 27 tpi. > >Straight pipe threads are used for electrical stuff; conduit fittings are threaded NPS as are lamp parts. > >Roy > >--- In 7x12minilathe@..., ToolRoomTrustee@... wrote: >> >> >> Classical meter wheel and four dial counter blocks from KAHLSICO. >> >> In my 28 year working life on National Oceanographic and Atmospheric Research ships as an oceanographic >> technician I often had to deal with the devices that measured amount of cable going out (and hopefully coming back!). >> >> The technology of the times late 60s to mid 90s (in my career) used a stainless steel grooved wheel with a nominal circumference of >> one meter that was suspended from a gantry or A-frame to allow working room for instrument packages. The wheel used a cable >> similar to a speedometer cable to connect to a mechanical contrivance with four dials to cover units, tens, 100s and thousands of >> meters. The meter wheel and four dial block used male threads to connect to female threads on end fittings of the connecting cable. >> I was essentialy self taught on the job with my own Unimat at first then later got some end of fiscal year money to buy a Unimat for >> my department. I determined that the threads were 5/16-24 which is a National Extra Fine so got a die and taps through govt supply >> system. Much later found that it was actually a ?x27 pipe thread. The NEF tap did work. >> My conjecture is that the NPT was used so the connections could be put on tight. >> >> Anyway, my query here is if anyone else has some examples of where pipe threads are used but not on pipes. >> >> Larry Murray >> > > > > >------------------------------------ > >Yahoo! Groups Links > ><*> To visit your group on the web, go to: > http://groups.yahoo.com/group/7x12minilathe/ > ><*> Your email settings: > Individual Email | Traditional > ><*> To change settings online go to: > http://groups.yahoo.com/group/7x12minilathe/join > (Yahoo! ID required) > ><*> To change settings via email: > 7x12minilathe-digest@... > 7x12minilathe-fullfeatured@... > ><*> To unsubscribe from this group, send an email to: > 7x12minilathe-unsubscribe@... > ><*> Your use of Yahoo! Groups is subject to: > http://docs.yahoo.com/info/terms/ > |
