failed somehow sketching rotating mast

[hammax]

... using the photo of cross section for sketches:

[chrisb]

One source I looked at had me using Sketcher, then import that into a body under Part Design for padding and stuff. I'm coming from Autocad so this is a new way of working, for sure. I have recreated my sketch using just lines and arcs on the left side, then a mirror for other half. So I have ImagePlane - Sketch - MirroredSketch and will try working from there. Thanks for the examples!

Sometimes it makes things more difficult, if you come from another system. But you are on a good way, as you don't seem to expect that FreeCAD should behave exactly like Autocad.

Although parts of it may be trivial for you, I recommend to work through the PartDesign Tutorials, because this may reveal some differences in the workflow.

A standard workflow could be this:
- switch to PartDesign workbench
- create a sketch; if you want, you can start with creating a body, and then create the sketch
=> this creates a sketch inside of a body, and there is nothing to import
- sketch half of the profile
- create a pad
- mirror the pad
=> You see that we rather recommend to mirror the created feature than the sketch. You can then don't need to switch to Part workbench and you stay in PartDesign.

Part workbench is based on the CSG approach and you may switch completely to this instead of using PartDesign. You can mix them, but you have to follow some rules, the most important being "use part tools only on the whole body, never on a feature or a sketch inside of it".

[hammax]

@chrisb ???
Is there a way to produce some kind of "master sketch" and get editable quasi_clones / links / duplicates of it,
where one is able, to take parts of it by changing the rest e.g. to construction lines,
and get this way dependent (from master sketch) "fractals" of the part,
which you can afterwards combine to a single part again?
So that all derivates are parametric to the master.
NOT external references in the usual way!!!

In my above example this was done, but it is not parametric, because of using sketch duplicates.

[chrisb]

@chrisb ???
Is there a way to produce some kind of "master sketch" and get editable quasi_clones / links / duplicates of it,

How about Sketcher CarbonCopy?

[hammax]

... I hope to understand it - seems to be a solid base after eliminating measure/constraint doublettes. => Next task!
Delete prior sketches and rebuild some to test.
https://forum.freecadweb.org/viewtopic. ... 30#p604768
Thanks for enlightening.

Mast_3.PNG (152.37 KiB) Viewed 401 times

[jadory]

Although parts of it may be trivial for you, I recommend to work through the PartDesign Tutorials, because this may reveal some differences in the workflow.

A standard workflow could be this:
- switch to PartDesign workbench
- create a sketch; if you want, you can start with creating a body, and then create the sketch
=> this creates a sketch inside of a body, and there is nothing to import
- sketch half of the profile
- create a pad
- mirror the pad
=> You see that we rather recommend to mirror the created feature than the sketch. You can then don't need to switch to Part workbench and you stay in PartDesign.

Part workbench is based on the CSG approach and you may switch completely to this instead of using PartDesign. You can mix them, but you have to follow some rules, the most important being "use part tools only on the whole body, never on a feature or a sketch inside of it".

I will work through the tutorials. I started working on Freecad a couple years ago and gave it up for the time being.. forgetting most of what i had learned. Maybe an age thing.. getting up there in years.

So was having a hell of time trying to figure out why my mirrored sketches wouldn't pad. Validate sketch showed troublesome vertexes at the join, so spent lots of time trying to research and resolve that. Laying in bed last night it finally struck me to pad each half individually because the join wasn't closed (open wire). Hammax I think in their example did so and I was finally able to understand that.
I could also try padding one half and then mirroring the pad as you say.

Next is to figure out how to model the base of the mast section with the trailer hitch. There is probably a way without having to resketch the inside portion of the mast section. Best practices? - maybe a new body for the base and import lines from the padded section to define shape?

Thanks much Chrisb - very helpful! /jd

[jadory]

So I am progressing in at least getting some things down on the design. However I have hit this:

Code: Select all

PositionBySupport: AttachEngine3D: Part has null shape
09:30:42  <Exception> AttachEngine3D: Part has null shape

So on my 4th body I am unable to progress. Not sure how to troubleshoot. The Body004 is to be a cylinder the hitch fits into. Been googling and will continue to do so.

Still using V0.20