Odd profile hole and slot question 2

[hygear]

I am still trying to learn GD&T and I have a few questions about a part that I'm making a drawing for (see attachment). Here are the questions I have:

1. The first feature that I'm having trouble with is special pivot hole used for a linkage with staked ends. The idea is that the linkage is inserted in this hole and rotated 90 degrees so it can not fall out of the hole. The position of the hole is important so I have a positional tolerance for that, but I'm a little unclear about what to do for the rectangular cutouts on either side of the hole. My first thought was to put a positional tolerance on the 13 dimension and a parallelism dimension on the 2.5 dimension. Later I thought it might be better to do a profile tolerance. Now I'm not sure what would be the best option or if either would be correct.

2. The second feature that is giving me trouble is a slot that exists the edge of the part. Normally I would put a positional tolerance on the width and height of a slot that is completely inside the part, but I'm not sure that will work in this situation. Any pointers?

 

[SeasonLee]

Question #1
Per 2009 standard, for the oddly configured feature we call it is irregular feature of size, you may use either Position and/or Profile of a Surface to control size, form, location and orientation relative to datum references.

When you choose Position to control it, be sure the boundary concept (the inner virtual condition) is applied, the example linked below is multiple geometric controls (Profile and Position) used, the profile FCF controls size and form while the position FCF controls location and orientation.

http://www.tec-ease.com/gdt-tips-view.php?q=153

You may choose Profile of surface to control this irregular FOS, please ref to the link below.

http://www.tec-ease.com/gdt-tips-view.php?q=155

You may also choose Composite Profile to control this irregular FOS, please ref to the link below for details.

http://www.tec-ease.com/gdt-tips-view.php?q=154

Question #2
Yes, you may use position to control the slot, you may also use symmetry to control it. If your design is symmetrically shaped part, you better to use the overall height (or overall width) as a reference datum, please ref to the link below for details. I will choose position control for this case just for easier to simulate the center plane.

http://www.tec-ease.com/gdt-tips-view.php?q=234

Season

 

[pmarc]

hygear,
Question #1:
Although the print shows vertical basic dimension Y, nothing really controls location of the cutout in vertical direction. Parallelism tolerance does not control any locational aspect of the cutout, it deals only with orientation. That said, the fastest and the easiest way to define the cutout would be:
- to add C as tertiary datum feature reference in position callout associated with width 13;
- to switch parallelism to position and use |A|B|C| as datum feature references.

The boundary concept does not necessarly have to be used here. Your geometry contains of 3 features of size (central cylinder, width and height of the cutout), thus 3 simple positional tolerances should work fine.


Question #2:
The main difficulty with this geometry seems to be proper control of depth of the slot.

The fast and dirty way to solve the dilemma would be to stay with current position tolerance and additionally apply directly toleranced depth dimension from the right edge of the part to arc's quadrant and get rid of basic X dimension. But in my opinion this approach would be very crude, quasi GD&T solution.

Actually, the fact that the slot is opened complicates things a little bit. Since it do not have opposite elements in horizontal direction, I think the easiest fully GD&T compliant option is to use profile of surface tolerance. The slot (its height, radius and distance X) would have to be defined by basic dimensions and profile callout with relation to A|B|C would have to be applied along the contour. If greater locational error of the slot is allowed in comparison to its size & form (width and length), composite profile of surface FCF could be used.

 

[hygear]

Thanks for the input guys. The information you provided should help steer me in the right direction.