Pocket two dimensions

[ianj001]

Can someone explain how the Pocket two dimensions is supposed to work.
I looked here https://wiki.freecadweb.org/PartDesign_Pocket
and searched the forums but didn't find a good explanation of how it works.
I was expecting that it would be dimension 1 is the offset from the sketch plane (start point) and dimension 2 is the end point of the pocket.
This would be very useful it worked this way.

It appears that is not the case but I can't really see what the outcome is supposed to be and how it really works. - The wiki is very brief.

OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.22611 (Git)
Build type: Release
Branch: master
Hash: 7eeec7a5990cc786723225ca8de16ca3186545b3
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United States (en_US)

[drmacro]

If the sketch plane is on a face, then with 2 dimensions one dimension is pocketing into space and the other into the face.

If the sketch plane is below the surface of the face it makes a void in the solid. (above and below the sketch plane)

To accomplish what you describe, simply change the sketch attachment offset.

It is indeed, very convenient.

[ianj001]

If the sketch plane is on a face, then with 2 dimensions one dimension is pocketing into space and the other into the face.

If the sketch plane is below the surface of the face it makes a void in the solid. (above and below the sketch plane)

To accomplish what you describe, simply change the sketch attachment offset.

It is indeed, very convenient.

So if I offset the sketch from it's plane then the first dimension in the distance from the sketch in one direction and the second dimension in the distance from the sketch in the other direction. This means the total depth of the pocket would be distance 1 + distance 2 centered around the sketch right? In other words, it's a asymmetric pocket as opposed to a symmetric pocket.

[drmacro]

So if I offset the sketch from it's plane then the first dimension in the distance from the sketch in one direction and the second dimension in the distance from the sketch in the other direction. This means the total depth of the pocket would be distance 1 + distance 2 centered around the sketch right? In other words, it's a asymmetric pocket as opposed to a symmetric pocket.

Yes. Of course if the values are the same then it is symmetrical. and if one value goes beyond the surface then well, it's just a pocket.

BTW, it is not recommended to attach sketches to generated geometry (i.e. the results of Pad, pocket. etc. operations due to the topological naming issue.)

You should instead attache to base planes and use sketch offsets.

[TheMarkster]

If you set length2 to a negative value you can achieve an offset. This works with pads, and I'm guessing it also works with pockets.

[ianj001]

BTW, it is not recommended to attach sketches to generated geometry (i.e. the results of Pad, pocket. etc. operations due to the topological naming issue.)

You should instead attache to base planes and use sketch offsets.

Thanks for the heads up. I am aware of the topological naming issue and use mostly base planes or datum planes. You have made sense of the two dimension part for me. I was missing the asymmetric aspect of it as I had the sketch on the same plane as the object I was pocketing.

[ianj001]

If you set length2 to a negative value you can achieve an offset. This works with pads, and I'm guessing it also works with pockets.

Yes, that does work. The second dimension becomes the "start point" then the first dimension is the depth. - Not massively intuitive but it works

[chrisb]

If you set length2 to a negative value you can achieve an offset. This works with pads, and I'm guessing it also works with pockets.

This was discussed recently (for pads) and IIRC there was an offset introduced which should do this. It is available for pockets as well but I cant get ot working here; neither for pads nor for pockets. Am I missing something?

[drmacro]

I remember a thread about using negative numbers. Is that possibly what you're referring to?

[chrisb]

I remember a thread about using negative numbers. Is that possibly what you're referring to?

Yes, and it rouse the question what the Offset in Pad and Pocket is for: