Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations KootK on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

perpendicularity question

Status
Not open for further replies.

duk748

Mechanical
Jul 18, 2007
167
hello - I was told today that I did not understand the use of perpendicularity - I have a piece that has 2 90 degree surfaces - the top surface is 10" long which is perpendicular to the front surface which is 36" long = the front surface is datum a the top surface is perpendicular to a within .001" - I was told that in this configuration that surface a could be out by at least .036" (.001"x36) - this does not seem right to me - I thought that surface b must lie between 2 planes within .001" perpendicular to surface a - I would think that if a straightness tolerance of say .001"per inch on datum a then that might apply - I just need to clarify it for myself - any help would be greatly appreciated - thank you
 
Replies continue below

Recommended for you

Please provide a sketch.

Certified Sr. GD&T Professional
 
File cannot be opened. Try again with no special characters in file name.

Certified Sr. GD&T Professional
 
duk748,

As per ASME Y14.5, perpendicularity is a linear measurement, as you have described. Perhaps your co-worker thinks it is an angle.

--
JHG
 
duk748

Your interpretation is correct. There is no ratio "multiplier" based on the length of the datum feature or the feature under control. See Figure 6-3 on page 100 in Y14,5-2009. Note too, when applied to a planar surface, there is implied flatness equal to the perpendicularity tolerance.

Certified Sr. GD&T Professional
 
hello again & thank you very much - i was sure i was right but considering his position i have to make it wrong - if you understand my meaning - thank you again for the vote of confidence - have a great day
 
Your welcome.

Certified Sr. GD&T Professional
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor