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Hi all. I am trying to figure out how to add a flatness tolerance to a thin plate so I can establish a derived median plane flatness tolerance in MBD. Solidworks will not let me do this. I keep trying to attach the GD&T feature control frame to the thickness tolerance but it will not let me. It only wants to let me select a face. Any ideas?

My understanding is that you would like to create something like this is this correct? Try something like this?
1. Click the thickness dimension
2. Click the Geometric Tolerance feature button
3. Apply your flatness tolerance requied and click OK

There are multiple way to attach a GD&T to a dimension, this is just one of the method

That is what I want to do, except I'm trying to do it in the MBD format.

Like this? See attached video.

This is in SolidWorks 2021 sp3. Not sure if there were problems in earlier versions.

dale.smith wrote: ↑Fri Jun 11, 2021 2:41 pm That is what I want to do, except I'm trying to do it in the MBD format.

Arh i see..
The way of using MBD is very different from normal drawing...

I believe you are looking for something like this right? You will need to create the dimension (10.00±0.25) using Size Dimension function instead of Location Dimension
When creating the Size Dimension, you will need to use the Create Width Feature (this window might be a bit difficult to find but it should appear once you click on a face when using Size Dimension)
Once you have the Width feature, you can attach the flatness GTOL onto it Hope this help!

I see, I managed to get it to work. Thanks to both of you!

zwei wrote: ↑Thu Jun 10, 2021 7:35 pm My understanding is that you would like to create something like this is this correct?
image.png

Try something like this?
1. Click the thickness dimension
2. Click the Geometric Tolerance feature button
3. Apply your flatness tolerance requied and click OK

There are multiple way to attach a GD&T to a dimension, this is just one of the method

Can you please elaborate on this. I'm trying to add GD&T to dimensions and can't figure it out. What is the "Geometric Tolerance feature button" and where do I find it?

The solidworks help provides this nugget of knowledge:

Create a geometric tolerance symbol.
Drag and drop the symbol onto a dimension.

I think I figured it out. You click the "Geometric Tolerance" on the "Annotation" tab. I was looking for it on the dimension properties window.