Hole Position to Self?
Hole Position to Self?
(OP)
Hello,
I was looking at this print from a supplier yesterday and after reviewing it for a while I came across something I just don't understand.
There is a hole controlled (compound feature control frame) with true position with respect to datums C and A and perpendicularity control with respect to datum A. So I go off and hunt down the location of these datums and I see that datum C is shown to be the center of the hole that's being controlled.
Does that make sense to anyone? Or is this a mistake?
See attached pdf.
Thanks,
Mod
I was looking at this print from a supplier yesterday and after reviewing it for a while I came across something I just don't understand.
There is a hole controlled (compound feature control frame) with true position with respect to datums C and A and perpendicularity control with respect to datum A. So I go off and hunt down the location of these datums and I see that datum C is shown to be the center of the hole that's being controlled.
Does that make sense to anyone? Or is this a mistake?
See attached pdf.
Thanks,
Mod





RE: Hole Position to Self?
RE: Hole Position to Self?
I really don't know... It looks like they're calling out the axis to be both Datum D and Datum C....?
....?
RE: Hole Position to Self?
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Hole Position to Self?
RE: Hole Position to Self?
Of course, none of them really know that much about GD&T but think they do, so I've got to do double duty to convince them of anything. That's sort of the reason why I posted here... To gain a little more input about this.
Thanks for the replies.
RE: Hole Position to Self?
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Hole Position to Self?
Also, it's just occured to me that they were probably trying to call out the axis of the pin on the other side as Datum C and then give the hole a position tolerance to the center of that pin (Datum C).
So it could all be fixed up nicely if they would just move that Datum Reference Frame from the axis of the pin to its outside surface.
RE: Hole Position to Self?
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Hole Position to Self?
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Hole Position to Self?
RE: Hole Position to Self?
As to your question ModulusCT. Position does control perpendicularity to an extent, in this case a diameter of .007. The perp control is a refinement. Normally the primary datum contacts on 3 points, so for holes is normally the surface that perpendicularity is measured to.
However, at the end of the day it's just plain wrong and should probably be looked at again based on function.
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Hole Position to Self?
Therefore "if true" I would suggest that the 2X pattern currently labeled [D] be changed to [B] making both 1.005~0.995 dia pins [B] just the way they function.
Again "if true" I would change the [pos|dia 0.007|C|A] to pos|dia 0.007|A] effectively making the spread between them basic +/- 0.007 and see if that works with your fit stack to the mating part. If it is too large reduce it to what fits and if the value approaches the tolerance refinement for each pattern feature's perpendicularity to [A] then eliminate the refinement.
Or if you cannot change it... then quit making a fuss because that is the way all the other connectors are defined and they have all worked fine so far.
Paul
RE: Hole Position to Self?
Cool thanks... I guess I'll have to give them a call and ask some questions about the part.
RE: Hole Position to Self?
Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group
RE: Hole Position to Self?
RE: Hole Position to Self?
Also that note "PIN FLASHING SHALL NOT EXCEED DATUM A" is rather cryptic. I guess they are trying to say, "NO PIN FLASHING ON DATUM "A" SURFACE."