True position with Perp control
True position with Perp control
(OP)
Can you use true position with a perpendicular control?
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True position with Perp control
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RE: True position with Perp control
Tunalover
RE: True position with Perp control
Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development
www.profileservices.ca
RE: True position with Perp control
One should not have a positional tolerance of 1 hole to the surface as I have seen on many drawings to qualify the secondary datum. In this case the drawing should have reflected a perpendiclarity rather than positional tolernace.
Dave D.
www.qmsi.ca
RE: True position with Perp control
Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development
www.profileservices.ca
RE: True position with Perp control
Positional to 1 hole relative to a surace reflects perpendicularity or any other angularity symbol which is the orientation. Why place positional when the appropriate symbol should be perpendicularity, parallelism or angularity? Doesn't make sense to me.
This is just something that I have seen over the years - pet peeve.
Dave D.
www.qmsi.ca
RE: True position with Perp control
Position does control perpedicularity however not tight enough so this is why I used both. I assume I am correct but was just checking.
RE: True position with Perp control
Dave, I'm not fussy about which way it's put on drawings because I understand that they are the same thing. I was doing it for a while a few years back because some German engineering colleagues had been taught that way in their technical programs, and their shop people had a bit of a time recognizing the perpendicularity, angularity and parallelism controls as being applicable to holes rather than just edges/faces. We trained it into them in time. The shop people that I was working with over here had no fore-knowledge of GD&T whatsoever for the most part, so it was easy enough for them to accept and understand the equivalence of the two methods, though they also indicated that it was easier if we just used the three orientation controls.
I'm a firm believer that only 5 controls are actually needed; position, profile of a line and profile of a surface, runout & total runout. Everything else is just a special case of these fundamental or "primitive" controls. Unfortunately, most users of GD&T (engineering or manufacturing side) don't have enough knowledge and experience to appreciate it. It is, of course, far quicker & easier to break these down into the special cases that each of the other controls represents, and teach or learn it on that basis rather than understanding how it all relates back to the "primitives".
Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development
www.profileservices.ca
RE: True position with Perp control
Can you describe the assembled condition that drives the tolerancing you are imposing? This is a new design IAW Y14.5-1994, correct?