How do I move a sketch in an axis?

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tonydiethelm2
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How do I move a sketch in an axis?

Postby tonydiethelm2 » Wed Mar 13, 2019 3:05 am

I have two sketches. I want to move one of them along the Y axis, so I can loft between them.

Apparently there's a bug where I can't edit the Attachment Offset without it weirdly rotating my sketchess, and I'm having problems finding the "Property Editor" which is suggested. Ah, it's available for the body, but I don't want to move the body, I want to move the Sketch.

https://www.freecadweb.org/wiki/Property_editor
https://freecadweb.org/tracker/view.php?id=3861

And no, recompute doesn't fix it. Edit: Yes it does, I missed it. Still bloody annoying.

Can someone help me out here and just tell me how to move a stupid sketch properly so it doesn't bug out? Or do I just have to rotate things back with the attachment offset and "manage" the bug?

OS: Ubuntu 18.04.2 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13541 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 9948ee4f1570df9216862a79705afb367b2c6ffb
Python version: 2.7.15rc1
Qt version: 5.9.5
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)
Last edited by tonydiethelm2 on Thu Mar 14, 2019 2:43 am, edited 1 time in total.
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NormandC
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Re: How do I move a sketch in an axis?

Postby NormandC » Wed Mar 13, 2019 3:24 am

tonydiethelm2 wrote:
Wed Mar 13, 2019 3:05 am
Apparently there's a bug where I can't edit the Attachment Offset without it weirdly rotating my sketchess
I doubt there is any bug about it, or we would have heard about it by now.

It may simply be a matter of not understanding that in Attachment, you move/rotate the sketch in reference to its attachment, not to the global coordinates.

You're saying that you want to move the sketch along the Y axis, which seems to indicate that it is attached to the XZ plane ? (It would have been simpler if you had attached your file)

If that's the case, then you need to change the Z value in Attachment Offset, not the Y value, because what you actually want is change the elevation of the sketch in reference to the XZ plane.

If that's not your problem, then please attach your file here, and detail the exact steps to reproduce the issue.

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pl7i92LCNC
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Re: How do I move a sketch in an axis?

Postby pl7i92LCNC » Wed Mar 13, 2019 7:55 am

he may use a Compound to take it to the Global AXIS
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HarryGeier
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Re: How do I move a sketch in an axis?

Postby HarryGeier » Wed Mar 13, 2019 9:16 am

Not sure, but he may have run into a problem which i have seen a few times also:

You have a sketch, somewhere in the middle of a design. You have some elements on it . Then when moving the sketch attachment with the property editor it MAY happen that the sketch seems to have lost his attachment plane. After save and reload of the whole, it jumps back to where it was. I also failed with pure F5 recalc in such situations. We also had a help thread on this yesterday. There it where Datum Planes that where jumping around after editing properties. Here recalc helped.

Next time i have that problem, i will post a sample..
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tonydiethelm2
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Re: How do I move a sketch in an axis?

Postby tonydiethelm2 » Thu Mar 14, 2019 2:40 am

NormandC wrote:
Wed Mar 13, 2019 3:24 am
I doubt there is any bug about it, or we would have heard about it by now.

I put up a link to the bug in my original post. It explains it quite well.

Ok, so.... Y'all are saying that to move a sketch on the XZ plane out on the global Y axis, I need to change the Z axis. Well, that is REALLY non intuitive.

Here's an example. Open it up, it's just a bunch of rectangles. Change an offset. The rectangles change their orientation for me. According to the bug documentation, that's only visual, not real.... and a recompute is supposed to fix that. And it does for me. But I'm getting sick of recomputes, and sick of missing something and fiddling with something that's visually wrong and doesn't need to be fiddled with.

I have no idea why my example rectangle is negative in the "Z" Y direction, relative to the unchanged rectangle.

All I want to do is use loft to create a simple guitar neck along the Y axis. Argh. This should be the easiest thing in the world.

The bug report says there's a better way to do it. If there is, does anyone know? I don't want to argue about bugs, I just want to move my sketch without a hassle.
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example.fcstd
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GeneFC
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Re: How do I move a sketch in an axis?

Postby GeneFC » Thu Mar 14, 2019 3:30 am

All three of your rectangles are parallel. There is no rotation at all. If there really was a bug (questionable) in the references in your first post it is unrelated to the effect your are seeing.

As explained above, the offset of a sketch is based on the local coordinate system for the sketch, not some global coordinate system. Sketches are planar (two-dimensional), and they exist in the x-y plane of their local coordinate system. If you want to move a sketch along a direction normal to its plane, that is the z-direction.

A recent feature in FreeCAD 0.18.xxxx offers display of local coordinate systems for objects. This image shows the LCS for your example file.

Capture.PNG
Capture.PNG (3.75 KiB) Viewed 737 times

Your example file shows correct behavior. Like it or not, that is the way FreeCAD works.

Gene
tonydiethelm2
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Re: How do I move a sketch in an axis?

Postby tonydiethelm2 » Thu Mar 14, 2019 5:20 am

GeneFC wrote:
Thu Mar 14, 2019 3:30 am
All three of your rectangles are parallel. There is no rotation at all.
Ok, well, this is a bit silly. I linked to the bug description. There's an example... You apparently didn't read what I wrote.

Tweak one along the axis using the attachment offset. They'll rotate.

This is a known bug. Why am I fighting y'all on this?

And I don't NOT like it, I just want it to be a bit more intuitive. Maybe I need to edit the documentation. I'll look into that.

And I read more.

It seems that an easier way to do this would be to use the Sketch -> Reorient Sketch tool. I can add my offset there. Way less fighting it? It does the same thing as changing the Attachment Offset, but is easier to understand. Maybe? Yeah, looks like it.

Out of curiosity, how do I fill out a feature request? I'm designing a ukelele, but would like to change the scale length easily. If I can change the offsets of the sketches I'm using to make the neck loft, it would be easy to change my scale length. Just about everything else is able to pull values from a spreadsheet. I'd love to have the sketch attachment offsets do that too.
freedman
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Re: How do I move a sketch in an axis?

Postby freedman » Thu Mar 14, 2019 6:33 am

You have probably read this;
It's about how to change propery data and make it stick with a recompute, it can be a bit tricky.

Also, it might be more intuitive if you put your sketches on the XY plane, then when you adjust the distance between them you use the Z axis.
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HarryGeier
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Re: How do I move a sketch in an axis?

Postby HarryGeier » Thu Mar 14, 2019 6:39 am

tonydiethelm2 wrote:
Thu Mar 14, 2019 5:20 am


Out of curiosity, how do I fill out a feature request?
Just wait a few days until the threads for requesting V 0.19 features begin to pop up. I am pretty sure there will be a thread discussing 0.19 wishlist . It makes no sense right now, to create that request just ..hours.. before release of 0.18

officially you create such a request after a discussion like her in the tracker

https://www.freecadweb.org/tracker/my_view_page.php
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tonydiethelm2
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Re: How do I move a sketch in an axis?

Postby tonydiethelm2 » Thu Mar 14, 2019 6:45 am

freedman wrote:
Thu Mar 14, 2019 6:33 am
put your sketches on the XY plane, then when you adjust the distance between them you use the Z axis.
Ah, this is all going into PATH for usage on a CNC machine. Orientation matters. and I'd rather bang my head against attachment offsets than bang my head against reorienting my whole part body before running it through PATH. :D :/