How to use the join tool in Illustrator CC 2017 2015 etc and trimming paths and lines
The join tool is a plugin for joining open paths and lines in Illustrator CC. The join tool is found beneath the shaper tool in Illustrator. The join tool works quickly with two paths. The join tool is super easy to use and apply and combine different paths in seconds. The join tool results in a sharp point design. You can then repeat the join tool and join other paths together. This tutorial shows you all the ways of using the tool and how to use it with curved designs, how to trim lines, how to combine lines and much more.
The join tool for Illustrator can be beneath the shaper tool in Illustrator toolbar and is for joining paths and trimming paths / lines / open paths etc. It works using two lines either selected or not (though personally, I generally select the paths I use and then use the join tool with the Illustrator paths)
1) Select two open paths such as two lines
2) go to the join tool in the Illustrator toolbar
3) pass over the closest ends of the two paths (and hope)
I say hope but the Illustrator join tool is a tool with a mind of its own and I am certain it is coded (unless it really does work using magic) in a particular way with logic to work with lines at a certain angle to each other or lines that are crossing but at times, it can also be an amazingly frustrating tool to use as even though the lines look as much the same as another pair, those lines will not join. Anyway, this tutorial shows the observations of the join tool that seem to work 99% of the time with lines and open paths but I am certain you will find times when it just will refuse to join a path even though the path look super close. Another point with the join tool is that it will result in a point, a sharp point in most cases and there is no preference to force it just to create a point to point (as with the pen tool) nor for it to generate anything other than a sharp point in the join (no wavy lines or curved joins)
and many more can be found throughout the site
Another issue with the join tool in Illustrator, if there is a fairly major overlaps with the lines you may find the join may fail and the paths may trim depending on where you pass the join tool over. The join tool does depends on where you pass over the lines. If you use the tool with a path overlapping another, and you use the join close to the overlap then the paths will be trimmed. The same paths can also be joined if you pass the tool over the end segments. This is particularly the case with multiple point paths or curved paths created with the curvature tool. It also depends where the pass over happens, if the overlap is a fair distance away then the lines will not be trimmed (again this is just an observation and I am certain you will find circumstances where the opposite happens)
You can see two lines with both lines point towards each other at one end and the other ends heading off to eternity (left image). You can use the join tool over the ends that are angled towards each other. There seems to be a cut off point. You can angle the line so they are close to parallel and the join tool will not work, you can then angle them at say about 80 degrees so they are fairly parallel and the join tool will not work but at some point where the angles can be joined (without the join flying off the page / artboard etc) you will get a sharp join when you pass the two lines with the join tool. On the left you can see the join by the red dashes
There also seems to be an issue with distance. If you select the same paths on the left image and perhaps move one of those paths down the page a little (but not changing the angle) and then try the join tool, it will at some point stop working even though the displayed angle is exactly the same. The image on the right shows much the same lines but they cannot be joined (certainly not by me). I am certain there is ainbuilt formula / algorithm for the join and the right lines fail.
On your left you can see two lines but the second line is nearly crashing into the first line but it is the end points are not particularly close or suggesting a join at a point. Instead the join results in a trim of the extended part of the left path and a sharp join replaces the extended line in Illustrator. The trim has shortened one of the paths.
In the image on the right, both single lines are crossing over and now the join tool being passed over the paths results in a trimming of both extended parts of the path. The trim is of the smallest parts of the extended paths for both.
1) select the two paths crossing over
2) pass over with the join tool
Again, there is clearly a logic in the way the trim is applied. If the lines are of equal length and at 90 degrees, the trim will not work. You can apply the join tool over the paths and neither side will be trimmed.
If you shift the lines up to create a smaller length of line then the trim will work using the join tool (though if you pass the join tool over the longer parts of the line division then the join will fail) - see image on the left with the red dashes being the part left by the trim / join tool.
On the right, the join tool can be used to trim two lines with a width profile added, the result is a single path with the same width profile. If the color is different or the width is different, one will take precedence and the new path ends up with the same width and color etc as on the right
Instead of just straight lines, this can also work with curved lines but the Illustrator join tool does not create a curved join (sadly)
1) click on the curvature tool
2) create a curved path
4) create another curved path using curvature tool or duplicate
5) move so the paths are not parallel but angled so the lines seem that they will join at a point (not too far off point) and that the ends of the lines are fairly close (seems to work best). A nice example being on the left.
With this combination of paths you can trim and also join (not at the same time) but if you pass the join tool over the two top end points (or slightly further down as well) then that will join. If you move over the overlap in the center or slightly below then a trim will happen (as shown in the left example). If you pass over the bottom points then nothing will happen.
Of course, once you have joined the paths (and the joins and trims result in a single path which ever way you look at it) you cannot re-use the tool again unless you select a second path
In the example on the right, the path above on the right was duplicated and angled to create two paths and then the join tool was passed over the end segments to create yet another single path. In that example, when the paths were not selected the tool seemed to fail to work, when they were selected, the path then worked and a single path was generated and again all with a single color and stroke etc
I am not sure how many paths can be combined or if there is a limit to the number points etc.
You can use the join tool to trim and join brush strokes as well (they are just strokes with an attached brush stroke)
The same resulting trim etc happens as explained above. Sometimes the actual brush stroke design may obscure the actual strokes making it a little less predictable.