Deep Bore Dimensioning
Deep Bore Dimensioning
(OP)
I am looking at a drawing that requires a couple of pretty deep bores (.375 dia x 20" deep). There is a conical positional tolerance zone locating the axis, presumably to recognize the possibility of drill wander, and there is also an axis straightness RFS callout associated with the FOS. I'm struggling with how to interpret the axis straightness requirement in conjunction with the conical shaped locating tolerance. I have no experience with deep bores such as this and I am inclined to suggest a simple perpendicularity tolerance at MMC. The 2009 standard has an example of using different controls at the ends of a FOS in para 7.4.3.
Your thoughts are appreciated.
dezignr
Your thoughts are appreciated.
dezignr





RE: Deep Bore Dimensioning
Tunalover
RE: Deep Bore Dimensioning
RE: Deep Bore Dimensioning
Tunalover
RE: Deep Bore Dimensioning
dezignr
RE: Deep Bore Dimensioning
Tunalover
RE: Deep Bore Dimensioning
Could you post an image to show what you have?
Best regards,
Alex
RE: Deep Bore Dimensioning
dezignr
RE: Deep Bore Dimensioning
Trying to combine straightness and position in this doesn't seem useful. One might look at it as the same problem as welding a thin rod to a plate. It may matter where it starts and where the end is located, but in between those two places the position of the center of each section is unimportant. It could be very straight, kink, or corkscrew, but as long as it is straight enough and the diameter is OK the rod would still function.
RE: Deep Bore Dimensioning
Thanks, dezignr
RE: Deep Bore Dimensioning
Don't forget that the applied tolerances apply to the entire length of the feature. In this case the pt is a straight line function of depth into the hole. The two pts don't just apply to the entrance and exit.
Tunalover
RE: Deep Bore Dimensioning