help in defining a surface
help in defining a surface
(OP)
I am designing a cylindrical fixture with a flat cut into part of it. There is a hole sunk into this flat (not a through hole).

I have the cylindrical diameter as datum A and the bottom flat as datum B. The bottom of the hole is the other important surface in this fixture, but I am confused as to how to describe it.
I thought to use a basic dimension from the centerline to the bottom of the hole, and call a profile tolerance on the surface at the bottom of the hole. However, I wasn't sure if a planar feature could be dimensioned from an axis in this manner. All points at the bottom of the hole are NOT equidistant from the axis.
Instead, I'm currently calling perpendicularity to datum B with a +/- size dimension ... though if I hold that dimension tight enough, does perpendicularity get me anything?
Thanks for the help yet again,
Matt

I have the cylindrical diameter as datum A and the bottom flat as datum B. The bottom of the hole is the other important surface in this fixture, but I am confused as to how to describe it.
I thought to use a basic dimension from the centerline to the bottom of the hole, and call a profile tolerance on the surface at the bottom of the hole. However, I wasn't sure if a planar feature could be dimensioned from an axis in this manner. All points at the bottom of the hole are NOT equidistant from the axis.
Instead, I'm currently calling perpendicularity to datum B with a +/- size dimension ... though if I hold that dimension tight enough, does perpendicularity get me anything?
Thanks for the help yet again,
Matt





RE: help in defining a surface
Based on the numbers used in the example, if you changed the .3250 dimension to a BASIC dimension and changed the perpendicularity tolerance to a profile of .001 in relation to primary datum A (RFS) and secondary datum B, the end result will be a tolerance zone that both locates and orients the datum C surface to the first two datums within a tolerance zone of .001.
I think that this callout would meet your design intent and clearly convey to downstream functions on how the requirement needs to be applied.
GDT_GUY
RE: help in defining a surface
Chris
SolidWorks 06 5.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 02-10-07)
RE: help in defining a surface
I think GDT_GUY's method is what I was trying to convey.
-Matt
RE: help in defining a surface
GDTGUY has a good answer.
Chris
SolidWorks 06 5.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 02-10-07)