Just in case it's not clear, even though you might have had every path closed in freecad, opening the file in Inkscape caused them to be broken up into individual segments.
I guess it sounds like you're more interested at the moment in fixing the freecad file, so I'll start with that. There are some relatively easy ways to connect all the short path segments. However, there are a lot of extra things in the file that you'll need to sort through, pretty much one by one, before you can isolate the path segments from everything else.
I'll mention some of those. Also, I'm only going to focus on the mechanical drawing part. You can figure out if you want to fix the rest of the document or not.
There are several paths, filled with white and with no stroke, here and there throughout. Some of them correspond to paths that you actually want to keep, and some don't. So you'll have to sort through and delete the ones that you don't want. For the ones that you want to keep, you can add a stroke and remove the fill, and then you won't have to fix the path segments for those areas.
See screenshots h1.png, h2.png and h3.png, showing the kind of detective work you'll need to do. At first, you can't see this object (the bottom rectangle which holds the circle) because it's white (h1.png). Add some color to it (h2.png) and you think you might see it. But move it over a bit and switch to the node tool (h3.png) and you can see that it is a complex object. Part of it, the tall, narrow part on the right is apparently underneath another white object or objects. I'm guessing you'll want to delete that one, but you probably know best.
Just that much might persuade you that drawing it in Inkscape from the start might not be a bad idea. But I'll show you some more of what I found, just to help you learn.
Looking at the corresponding rectangle at the top. For some reason, that one looks more like what you might expect. (h4.png) I've added a wider blue stroke, just to show some things. First, most of the path segments are joined, except for the bottom-left corner. And literally, I find that out by dragging the nodes around to make sure there are 2 paths coming out of a node. If a node only has a path associated on one side of it, the path is not closed there. If a node has 2 path segments connected to it, the path is closed at that node. Then I just Undo after I learn what I need to know.
1 - For some reason which I don't know, there are several nodes along the top edge of that rectangle. Ideally, you'll want to delete all those in the middle. With the Node tool, drag a selection box around all except the 2 at the corners, then Delete.
2 - To join the nodes at the bottom-left corner, drag a little selection box around them. (Since they are precisely on top of each other, you can only select one of them by clicking. But dragging the selection box select however many nodes may be there - 2 in this case.) Then Join selected nodes button on the Node tool control bar (or whatever the key shortcut is).
3 - Remove the fill.
Now, that path is fixed, and you no longer need the paths underneath (see h5.png) which are made of 4 separate segments. In my screenshot, I have it moved to the side. But actually, if you do that, how will you be able to get it back in the right place, after you delete the separate path segments that you no longer need? Not very easily. So instead of moving it over, while it's selected, do Object menu > Lower to Bottom (or this button on the Selection tool control bar
). Now you can easily select the 4 segments (because now they are on top in z order) and delete them.
There are several more white objects scattered around. You may have some idea where they are, from when you drew it originally in freecad. But you could also use Edit menu > Find, to locate them all. Or there's a new feature which I haven't used. I believe it's Edit menu > Select Same. I think with one object selected, that will select all the others like it.
Now for the 2 circles. The top circle is whole. But move it to the side for a moment, and you can see a circle made of several broken path segments. They don't even look like they were ever connected together. Here's the best way to delete those many segments, without having to move the circle over, and thus have a hard time getting back into place. Or I should say, it's the technique I would use. Others might have different approaches which they prefer.
1 - With Selection tool, drag a selection box around the circle. This selects the whole circle as well as all the pieces underneath.
2 - Press and hold the Shift key. The Shift key allows for multiple selections. Actually you already have a multiple selection, but you're about to de-select the whole circle, so you need the Shift key to keep from de-selecting everything.
3 - Click once on the circle. Since the whole circle is on top, it will be de-selected.
4 - Delete. This will delete all the many pieces below, and leave the whole circle intact.
The bottom circle.... Hhmm, it seems for some reason, the broken segments for this circle are on top of the 3 large segments. To be able to select those 3 segments, I can't only suggest trial and error, clicking short distances apart around the circle, until you find the 3 large pieces. Hold the Shift key, to make the multiple selection, one at a time. If you accidentally click a tiny piece, click it again, to deselect. Pay attention to the bounding box (dashed line rectangle around it). The next time you click, click just outside where the bounding box was, and you'll probably select one of the 3 large pieces.
I think I've given you the info you need to join them already. After they are joined, and while it is still selected, click Object menu > Raise to Top (or this button
). Now you can use the same technique as the other circle, to delete the broken pieces.
After you have removed all the white pieces, you should be able to relatively easily join all the broken pieces together. (I mean about the mechanical part. The parts of the drawing which create a document....well, I haven't looked at those parts yet. Anyway, I would suggest using this extension, to join all the segments:
https://github.com/fablabnbg/inkscape-chain-pathsIt can be done without an extension, but usually requires a bit of cleanup afterwards. I haven't not used this extension myself, but I've seen good reports about it.
For the selection tips I promised earlier. I suspect it was mostly those white objects which you can't see, are responsible for most of the problem. However, it is hard to select objects which have no fill and only a narrow stroke. You can adjust the precision of your mouse, so that Inkscape selects what is directly under the mouse, and not a few pixels away. Inkscape Preferences > Input/Output > Input Devices > Grab sensitivity. I have mine set at 2.
And just for good measure, a few more gems.
I'm not sure if you've run into this problem yet. But you might want to consider custom styles for your tools, if you didn't already see this.
https://forum.inkscapecommunity.com/index.php?action=articles;sa=view;article=15And if size and precision is important (which I assume probably is) you might want to switch to a geometric bounding box. (If you didn't already find that too.) It does not include the width of the stroke, in the size of the object. Inkscape Preferences > Tools, and check Geometric Bounding Box.
Depending on your options, the stroke width might be scaled when you scale an object. Therefore, the size of the object changes differently than you intended, if you're using the Visual Bounding Box option. While the Geometric BB avoids that, you can also disable that option. Inkscape Preferences > Behavior > Transforms, and uncheck Scale Stroke Width. You can also find this option on the Selection tool control bar:
I guess we'll come back to the hatching after you've digested all this much. Or maybe someone else will address it?
(click on attachments to make them bigger)
