Proper way to define over-sized pitch diameter threads.
Proper way to define over-sized pitch diameter threads.
(OP)
Hi,
I was looking for the proper way to define and over-sized tapped hole, along with a source to find this information.
It is and M3 x .5 and I am using a D13 over sized tap. So .013mm * 13 = 0.169mm oversize pitch diameter.
Would the proper form be something such as "M3 + .169mm X .5"
If anyone has a good reference source for information like this, it would be greatly appreciated.
Thank you in advanced.
I was looking for the proper way to define and over-sized tapped hole, along with a source to find this information.
It is and M3 x .5 and I am using a D13 over sized tap. So .013mm * 13 = 0.169mm oversize pitch diameter.
Would the proper form be something such as "M3 + .169mm X .5"
If anyone has a good reference source for information like this, it would be greatly appreciated.
Thank you in advanced.





RE: Proper way to define over-sized pitch diameter threads.
Special diameter-pitch threads, developed in accordance with this Standard, shall be identified by the letters SPL following the tolerance class. Below the designation shall be specified the limits of size for major diameter, pitch diameter, and minor diameter.
EXAMPLE: External thread
M6.5 1 − 4h6h − SPL (22)
MAJOR DIA 6.320 − 6.500
PD5.779 − 5.850
MINOR DIA 5.163 − 5.386
EXAMPLE: Internal thread
M6.5 1 − 4H5H − SPL (23)
MAJOR DIA 6.500 MIN.
PD5.850 − 5.945
MINOR DIA 5.417 − 5.607
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Proper way to define over-sized pitch diameter threads.
Found your example in the Machinist's handbook after searching ASME B1.13M.
I appreciate it.
RE: Proper way to define over-sized pitch diameter threads.
Based on the OP description, I think the correct reference is para 7.9, which reads:
Notice that not this results in a somewhat different designation than para 7.6. In particular, the tolerance grades/allowances aren't specified in the first line; also all size elements are given, and the non-standard ones are further identified by SPL.
RE: Proper way to define over-sized pitch diameter threads.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Proper way to define over-sized pitch diameter threads.
I actually went ahead and used the definition for coated or plated threads as this was the reasoning behind the over-sized threads in the first place.
Thank you for sending me to the right place.
RE: Proper way to define over-sized pitch diameter threads.
RE: Proper way to define over-sized pitch diameter threads.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future