How to preserve a curve when using the "rounded corners" effect on my shape?

Question

I am trying to round the corners of a custom shape, but it is just straightening the original curves out.

Note: This is in Illustrator CS5

Here is the shape before the effect:

The 3 "corners should be rounded".

Here is what happens when I use the effect:

How can I preserve the curves, and just round the actual corners?

Answer 1

I don't have CS5, but this should work:

Select your path. With the pen tool selected, create points on each side of the anchor points, something like the following:

With the white arrow tool selected, click one of the original cusp points (i.e., corner points) and then Shift-click the other two to select all three. Then, click the Convert selected anchor points to smooth icon in the toolbar at the top of the screen (alternatively, with the pen tool selected you can Alt or Option-drag on a corner point to convert it to a smooth point):

You should end up with something similar to this:

With the white arrow tool, drag each of the bulging corner points inward until they look appropriate:

Here's the new path overlaying your original shape.

If you want the corners to be more rounded, make sure the anchor points you added in the first step are farther away from the corner points.

Answer 2

Purely for comparison’s sake, I thought it would be good to show what Adobe Illustrator CC (in this case, I am using v2017) can do:

1. With the selection tool, select your entire path
2. On a Mac, hold down COMMAND key (CONTROL on Win).
3. Click and drag on the corner radius circle icons that appear
4. You can optionally select a specific point and just round the corner for that part of your shape

Double click one of the circles for corner options:

Answer 3

My way is easier if you have good experience with the pen tool.

First, make your triangle. In my case, I just made a box, deleted 1 anchor point, joined the two points creating a segment opposite to the middle point and rotated about 45 degrees (please correct me if I'm wrong).

Next, hit the convert path to rounded corner button. I'm pretty sure this feature is already in CS5. Make sure you have the point selected when doing this.

Do this one by one for each of your points. The one in the middle should be the easiest one to convert. The one at the top and the bottom are a bit tricky but nothing a pen tool can't fix :)

As you go each of the top and the bottom points, with your Direct Selection Tool active, grab the furthest to the left angle for the point being selected and while holding Shift, bring it to the center creating a nice straight side but still rounded corners.

It should look something like this:

Again, do the same thing for the bottom and you will get this:

I hope this helps! Please let me know if I confuse you. I'll be glad to clarify myself some more.

Answer 4

The simple way: Create additional anchor points around cornes (as it was mentioned at first answer), then apply Round Corner effect as usual.