Got a Tech Drawing today with measurements and all that. I understand everything except for one part where they've specified a bolt with M4 P=0.35. The M part I get but what does the P specify?


I would go with Pitch of 0.35mm ie 1 turn advances by 0.35mm

A view of the drawing may clarify this.

  • $\begingroup$ The standard fine pitch of an M4 thread is 0.5mm, so this is a non-standard thread that shouldn't strictly have been given an "M" designation. The fine pitch of M2.5, M3, and M3.5 are all 0.35mm, however, so it's not a completely oddball value of pitch. $\endgroup$ – Jonathan R Swift Feb 25 '19 at 22:23
  • $\begingroup$ @JonathanRSwift makes you wonder if some drawing package did a rounding when it should not have... $\endgroup$ – Solar Mike Feb 26 '19 at 19:08
  • $\begingroup$ Yes... should be able to measure the diameter to confirm though, so better that be in question than the pitch. $\endgroup$ – Jonathan R Swift Feb 27 '19 at 4:32

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