Parallelism on a Slot 1

[random_guy]

Can parallelism be applied to a slot?

Y14.5-2018 shows it applied as a refinement to position of a hole (Fig 9-9 and 9-10).

If I wanted to control orientation of the slot to a datum plane, but not necessarily position, I don't see why I couldn't.

If it's applied in this sense, what does that ultimately mean? The center plane of the slot must be oriented within that tolerance to the datum?

Wise men learn more from fools, than fools do from the wise.

 

[3DDave]

Yes it can be.

"The center plane of the slot must be oriented within that tolerance to the datum?"

That's it, subject to any size modifier that may allow the tolerance to increase or decrease based on the feature size.

 

[random_guy]

That's what I thought. Thanks Dave!

Wise men learn more from fools, than fools do from the wise.

 

[powerhound]

If I wanted to control orientation of the slot to a datum plane, but not necessarily position, I don't see why I couldn't.

You would certainly want to control the position, unless you are controlling position with respect to a different datum. If you only control orientation, then that's ALL you are controlling. There is no implied location with an orientation control.

John Acosta, GDTP Senior Level

 

[3DDave]

Maybe this slot will be used as the secondary datum feature for all other features and has no position requirement.

 

[powerhound]

Dave,
If the slot is parallel to a primary then it needs to be located from it, which means position would be the appropriate control. Maybe there's an instance where parallelism would be appropriate. Can you describe a scenario like that?

John Acosta, GDTP Senior Level

 

[3DDave]

Sure. There is an overall profile tolerance.

 

[jassco]

Hi, Randon_Guy:

What is "parallelism of a slot"? Are you talking about feature of size or orientation to other features?

Best regards,

Alex

 

[Burunduk]

I agree with John.
There isn't much sense in having a secondary datum feature slot parallel to the primary. Pretty much like a secondary planar datum feature parallel to the primary planar datum feature, it is useless. 

 

[random_guy]

I agree that it's not ideal, and it's not how I'd apply the GD&T, but it's not my drawing.

Dave is correct in that an overall profile tolerance controls the location, and the parallelism is a refinement of orientation.

Wise men learn more from fools, than fools do from the wise.