[Solved] I don't understand how to use Techdraw

[freedman]

It appears I just lost 6 hours worth of dimensioning. I had all my drawing dimensioned and closed the program last night. Today I open the program and have to update all the drawing as usual to get them to display, that worked. I had a little problem with the model and had to adjust one sketch. Now every drawing as it updates has thrown the dimensions all over the place, totally unusable.
Question: Even if I can go to a backup how am I supposed to update the sketch I changed without this occuring?

[chrisb]

You got probably trapped by the horrible topological naming issue.

how am I supposed to update the sketch I changed without this occuring?

How can we tell without knowing anything from your model?

[freedman]

How can we tell without knowing anything from your model?

There's no way I can put the clients product on the site.

Going into this I felt like the model updating all the time would/could become an issue. I guess I was hoping that TechDraw didn't work off of the same naming as the model, I should have asked. I think there should be more of a warning, it's one thing to fix a couple links in a model, it's another to loose hours worth of detailed work on multiple drawings with almost no way to recover. Maybe Techdraw needs to work differently, I wonder what the big CAD folks do that keeps this from happening? They have errors also.

So, I am back to AutoCAD. At least I can export to DXF. I also noticed that when I export to DXF some of the arcs have turned into straight lines, is there something I can do to minimize that? I will try the shape 2D view and see if that helps.

Thanks

[reox]

Question: Even if I can go to a backup how am I supposed to update the sketch I changed without this occuring?

AFAIK currently it is not possible to change the sketch without having issues with the dimension lines, as they also have the topological naming problem.

[wandererfan]

I think there should be more of a warning

from TechDraw_Dimension_Length:

TopoNamingWarning.png (30.16 KiB) Viewed 448 times

[freedman]

There is a reason behind my subject line of this post, I really don't understand how to use a drawing tool where the drawing work can be lost. First off, thank you wandererfan (and others) for your work, none of my comments here are directed at you, you are working with what is available.

I'm hoping this can be a starting point to focus on drawings and there importance in CAD. I feel almost every CAD designer will agree that you can trash my model but the drawing has to be isolated in some way. Drawings are the root of manufacturing and they need to be preserved, at all cost. Models can always be recreated but it doesn't work the other way around, you can't recreate a model without the dimensions from a drawing.

So, to work, what is available and what can be done, here is one concept I can think of:

Concept #1) Once a drawing is created it can't be erased and nothing on it can be moved (after placed), items in the drawing can be deleted or added without a recompute. If you need to make a change to the model then you have to save the FreeCAD file, close it and open it once again. At opening a switch will need to be set to make drawing changes, normally the user would upgrade the part number of the file name at this point.

I don't know how to make this all happen but I think it handles the model changes, file saving, part number handling.

[triplus]

When i am satisfy with a technical drawing i usually save it in a SVG and PDF format.

[freedman]

items in the drawing can be deleted or added without a recompute.

This is probably the toughest one. Is there a way to get dimensions from the (created 2D shape) without it being linked to the model? It seems the only way to preserve a drawing is to have it linked to something that can't get updated. I was thinking anytime you create a drawing a 2D shape is created and stored with the drawing. Then add a switch to the 2D shape for updates at program start.

[freedman]

Concept #2) Once a drawing is created from a model no further changes can be made to the model, all sketches and features are locked. Recomputes can take place and I believe the model can not have topological errors unless something in the model changes, that might have to be answered by a super-user. To change the model the file would have to be closed and reopened (renumbered hopefully) and a switch set to change the model.

[triplus]

If you know you will be going back in the design history and will do things such as add and remove Sketcher geometry. And when doing that, if you don't want for existing drawings to change.

Use Part CreateSimpleCopy and base the drawing views on such feature instead.