gettng started

[edsut]

Hi,
I am brand new to FreeCAD (spent a few days over Christmas break working with it). I've been using Sketchup for years, and have dabbled with OpenSCAD, but I'm hoping I can transition off Sketchup to FreeCAD for all of my 3D printing work. I've watched and followed along with a lot of excellent tutorial videos from MangoJelly (started with https://www.youtube.com/watch?v=DcNlm8JAfJc) and they have been a great start. Now I'm attempting my first "from-scratch" part and relatively quickly I ran into a snag trying to do something I thought would be simple. Refer to the attachment (drawn with sketchup) to see what I'm trying to create.
I started with a rectangle, added an arc and then padded it out 1.5". I thought I could then click on the face and create a second rectangle (coincident with the first) without the arc and then just pad that out an additional 1.5". I just couldn't get that to work. When I would click on the pad tool for the second portion of the part it would fail. I had tried the "Copy Geometry from another Sketch" button so that I could constrain the second rectangle to points on the first rectangle, FreeCAD wouldn't let me do that.
Note I'm using 0.19 on W10.
Any suggestions?
Thanks in advance,
Ed

[jmaustpc]

Create a sketch containing a rectangle
Pad the full length
Create a second sketch with a circle
Pocket to length required

[Shalmeneser]

[Shalmeneser]

[TheMarkster]

Using SubShapeBinders we can do this in one sketch. The edges must be created in a manner allowing independent edge selection where needed. Here is the sketch:

Snip macro screenshot-65fcfa.png (44.9 KiB) Viewed 2458 times

The first subshapebinder:

Snip macro screenshot-80f539.png (25.7 KiB) Viewed 2458 times

The other binder:

Snip macro screenshot-5cd116.png (24.58 KiB) Viewed 2458 times

The model:

Snip macro screenshot-e89739.png (33.97 KiB) Viewed 2458 times

One binder is padded in one direction, the other in reverse.

Take note that the sketch itself cannot be used directly because of the T connections. There must be only 2 edges at each joint. Therefore, we must use the binders with such a sketch.

Edit: Note also that even though this works it has the disadvantage that if the sketch is edited it might break the subshapebinders due to a bug in FreeCAD. See topological naming problem.

[edsut]

Thanks for all the responses!
I'm replying to jmaustpc initially because this is the solution that makes the most sense to my newbie brain...

Create a sketch containing a rectangle
Pad the full length
Create a second sketch with a circle
Pocket to length required

I guess I'm missing some step because this leads me down the same path as my initial attempt. Here are my steps (note that I am assuming that the best way to do this is to just start with a profile sketch, then as I add features, just add sketches to various faces (planes) as needed. If this is wrong, please inform)..
1. I create the body, open up a sketch and pad the full length.
2. Then I create a second sketch on the face of the padded body. Now I create a second sketch, and I assume that I have to constrain points on this new sketch to coincide with the face of the initial part (is this correct?). First I tried to use the "Copies geometry from another sketch" button, but that doesn't work at all. Then I tried the "Create an edge linked to an external geometry". This seemed to work, so I created one edge for each of the four sides of the padded face, then added an arc. This was fully constrained, but I couldn't pocket it. Note I didn't use a circle 'cause half of it would be outside the plane that I want to pocket. See attached project.
Thanks for any help you can provide.

[chrisb]

The technique with the external references is the right one. However, the magenta coloured edges are usable only for reference, the are not what we call "real geometry". Draw your geometric elements as you did before and use these edges only for constraints, e.g. coincidence or point-on-object.

While at your state of knowledge it may be ok, it is not really recommended to attach sketches ot faces. or to reference edges of a pad or other generated geometry. Better place the sketches on the main planes and reference other sketches. It helps to avoid the topological naming problem. You can toggle the visibility of features and sketches for this.

[drmacro]

Can't have open shapes in the sketch.

Close the shape.

Shouldn't attach to generated geometry, Use Attachment offsets to avoid topological naming problem.

edsut.png (130.7 KiB) Viewed 2319 times

[edsut]

Sorry, something just isn't clicking yet...
@chrisb Are you saying that I should create the second sketch (with the arc) on the same plane as the first sketch?

[edsut]

Can't have open shapes in the sketch.

Close the shape.

Shouldn't attach to generated geometry, Use Attachment offsets to avoid topological naming problem.

edsut.png

Not sure what you mean by an "open shape".