Position of hole
Position of hole
(OP)
Struggling to understand allowable tolerances with GD&T In this drawing how far off could the .228 hole and counter bore vary from true position and still make an acceptable part?
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RE: Position of hole
1. Not everyone on this forum has AutoCAD, so it would be really helpful, if you converted your .dwg into a .pdf document, or a picture (.jpg, .png, etc.)
2. Your hole doesn’t have true position, because it serves as a datum, so anything else is positioned (sometimes incorrectly) relative to it.
RE: Position of hole
RE: Position of hole
Also, the drawing does not define acceptable amount of coaxiality error between the thru hole and the c'bore. This relationship is simply missing. Positional tolerance referencing to Y(M) and applied to the thru hole could be used here.
Another thing - datum feature Z is not feature of size, therefore position tolerance usage to control location of radius relative to datum Y is not recommended. There was an interesting discussion recently about this topic: http://www.eng-tips.com/viewthread.cfm?qid=359996 .
In my opinion there are more issues with this drawing, but solving the abovementioned three will be pretty nice starting point.
RE: Position of hole
The biggest issue here is that normally you don’t use Position to control radial feature less than 180°. You should consider using Profile. On the side note, your drawing doesn’t even directly specify where the center of radii is located.
Also the choice of datums seems to be questionable.
I'd try to "reverse" it, making hole/counterbore controlled feature/secondary or tertiary datum
Unfortunately I cannot just redraw your drawing “correctly”, because I don’t know how your part functions. Which features are supposed to fit with the mating parts, which features just provide broad clearance, etc.
I am posting from work and really tight on time right now. Sorry.