thread calculation
thread calculation
(OP)
Hello,
In our shop we were cutting a small bar for it to be threaded into another threaded hole. I do not know the dimensions of the hole the threads fit into however we had to change the 1/2-28 to 0.497 -28. I'm not sure whether it was a UNC,UNF. Apprently it fits like a glove so its correct.
However,
How do i find this value(0.497) in the machinist handbook? i'm having problems locating it.
thanks,
In our shop we were cutting a small bar for it to be threaded into another threaded hole. I do not know the dimensions of the hole the threads fit into however we had to change the 1/2-28 to 0.497 -28. I'm not sure whether it was a UNC,UNF. Apprently it fits like a glove so its correct.
However,
How do i find this value(0.497) in the machinist handbook? i'm having problems locating it.
thanks,





RE: thread calculation
RE: thread calculation
i find it to be 0.4768 which is the basic Pitch Diameter. I looked under table 3c. extra fine thread series. It is 23tho less than 0.5. We cut it to 0.497. he said it was tight but did fit.
does that sound right?
RE: thread calculation
If 0.497 is the measured "O.D." of the thread that is only .003" under the theoretical major diameter, which is practically perfect.
RE: thread calculation
The major dia of a 1/2-28 UNEF is 0.500.
we cut it to 0.497 however i don't see how we got that number. Why didn't we just cut it to 0.500?
Is there a rule?
thanks
RE: thread calculation
tolerance is 2A-allowance of 0.0011.
This screw did fit up into an ID threaded ring.
They are external threads so i think im in the right heading.
Internal designation is for ID threading.
comments?
thanks,
RE: thread calculation
There isn't a rule, so to speak. There are established standards and the numbers in the Machinery's Handbook reflect those standards. The major diameter of a 1/2-28 3A is .497-.500. For a class 2A fit the major diameter is .496-.499. There is no good reason to change the designation from 1/2-28 to .497-28. I have gone through this exact issue before with an inexperienced engineer who thought that the reason a 1-8 bolt didn't thread into a 1-8 hole was because both components were 1" so they were trying to occupy the same space. I had to explain to him that there was already clearance built into the specification and no adjustment to spec was necessary. I'm not saying that inexperience is the cause of your dilemma but it's more often that I've seen interfering pitch diameters than major or minor diameters.
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: thread calculation
how did you find this? i'm looking in the unified screw thread section
RE: thread calculation
RE: thread calculation
how did he get 0.497?
RE: thread calculation
RE: thread calculation
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: thread calculation
which column or row did you read from the first time?
fyi i have 21st ED.
RE: thread calculation
which column or row did you read from the first time?
fyi i have 21st ED.
Engineer and Programmer
MasterCAM X6
Solidworks 2012
RE: thread calculation
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: thread calculation
RE: thread calculation
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?