Position of hole

[Bobref]

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?

 

[CheckerHater]

I see two problems here:
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.

 

[Bobref]

Thank you for your suggestion. I attempted to convert it. I understand that it is a datum and the R .860 is being held to position to the hole and counter bore. I guess my question is if everything is central and the .228 hole and counter bore are off how far off can they be? The feature that is important is the counter bore to the radius. Would you be so kind as to tell me how you would correct their mistakes? Thanks for your help for a newbie.

 

[pmarc]

The fact is that the drawing does not clearly communicate which feature - thru hole or c'bore or both - is the datum feature Y. This shall be clarified. Perhaps by splitting the entire hole/c'bore callout into two separate callouts and by associating datum feature Y symbol with the c'bore dimension (if the c'bore is the datum feature).

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.

 

[CheckerHater]

Really don’t know where to start.

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.