Threading question

[lpeedin]

Maybe I don't know the proper search terms so I'll provide an example & hopefully someone can clue me in on the formulas, math, etc. to get to the correct answer.

Example: I have a work piece with a bore that measures .930". In that bore I cut 10 TPI internal threads. What diameter should I turn the male piece that will have matching external threads?

These are arbitrary values, so like your high school math teacher I'm asking that you "show your work".

Thanks


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[DAT510]

Are you cutting a Standardized thread such UNC (Unified National Coarse) or UNF (Unified National Fine) ?

If so, I use a thread chart/table to give me the Major and Minor Diameters for both the Internal and External Treads.

Such as:
External: http://www.engineersedge.com/screw_threads_chart.htm
Internal: http://www.engineersedge.com/thread_strength/internal_screw_threads_chart.htm

If you are making up your own thread diameters, I believe you would need to calculate the "Pitch Diameter", plus/minus some for clearance. If I remember correctly the Pitch diameter in theory should be "the same" for both the internal and external treads.

Pitch Diameter: http://www.boltscience.com/pages/screw3.htm

Hope this helps,

Chris

 

[rlgustin]

Just curious are the 60 degree or acme threads (29 degree)

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[lpeedin]

60 degree


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[Wreck™Wreck]

Such a thread might be considered a 1 1/32-10 thread

Minor diameter .930
Maximum Major diameter 1.031
Pitch diameter .966

Not being in the ASTM thread standards roll your own as far a Min/Max dimensions go.

Make the external thread first which is easily measured over wires.

 

[bpimm]

Here is a calculator I found when I was doing a custom thread. http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx

Hope it's OK to post a link here.

 

[4GSR]

Here's all you need to figuring thread bore, thread OD, pitch diameters, and other thread parts. I use this everyday in the design work I do for my job.

http://www.hobby-machinist.com/resources/thread-program.2496/

Ken

 

[royesses]

I just uploaded a program called Threads.zip in the downloads section:
http://www.hobby-machinist.com/reso...-specsmajor-minor-wires-pitch-tap-drils.3162/

Has all the needed specs for internal and external threads. Include 3 wire information and measurements and tap drills with percent engagement choices.
unc, unf, unef, unj, npt, acme, uso threads. I've been running this since 2006 with no problems on win xp and win vista 64. Should run on just about any version of windows. I downloaded it as a freeware program.
I have scanned it many times (I scan my computer every day) for virus and malware. It is clean.

Roy

 

[bfd]

I will sound like a broken record but the machinery handbook has all the information you need you just need to practice using it. the info is there look and you will find. bill

 

[royesses]

I will sound like a broken record but the machinery handbook has all the information you need you just need to practice using it. the info is there look and you will find. bill

Not a broken record a voice of experience and wisdom.