Using a fillet on two curves

[b13]

Fillet works fine on a single curve and straight lines, but I'm having trouble using the fillet command on two curves (arcs). I have two circles which I have trimmed into arcs roughly to the correct length, when I try to fillet them (with various radii) the filleted curve either connects to the wrong end of one of the existing curves, or the filleted curve curves in the wrong direction. I've used this tool a lot before and have never had problems - until now. Is there a way to decide which way the fillet curves?

 

Any advice would be much appreciated.

 

Ben

[eldon]

It would be really helpful if you could show a picture of your troublesome arcs.

 

It is difficult from words alone to picture your problem.

 

Sometimes it is easier to draw a complete circle, initially, using the TTR option instead of using Fillet, than fighting with something that has a mind of its own.

[b13]

Eldon, please take a look at these screenshots.

 

The first shows the desired image - done with large circles (red), trimmed down then dragged into (roughly) the right place.

 

The second shows my attempt using fillet (green). the lowest curve refuses to even connect to the correct side of the central arc (yellow).

 

I hope this makes sense and are able to help further.

 

Ben

[b13]

Right, here they are.

[eldon]

I think that I would stick with my previous advice to draw a complete circle with the TTR option, and then trim.

 

Sometimes there is no rhyme or reason as to why AutoCAD behaves in a certain way, and it is quicker to take the easy way than to try and make it behave as you would like it to.

 

If you could manage to post the drawing file, then I could see if it behaves in the same way as you are experiencing, otherwise go the TTR route.

[JD Mather]

Keep in mind that circles (arcs) are calculated in a CCW rotation and this can sometimes give a clue to more reliable selection order, but in the end, I stopped worring about little things like this a long time ago. Simply do the c ttr tr as suggested and move on.

[b13]

Thank you both, TTR it is then. It's just annoying because fillet works perfectly most of the time. Maybe an issue with curves?!

 

JD Mather, no matter which order each point is selected it doesn't make a difference, but I get what you mean with the direction of rotation.

[Organic]

I often have trouble fileting between curves in AutoCad. I either use the TTR circle option or depending upon the complexity, import the linework into a civil software package that can do it.

[BIGAL]

We use other CIvil software and its smart enough to know that some of these arc-arc combinations actually have 4 solutions so it will ask which is correct or where is 3rd center pt. The fillet problem has been with Autocad basicly from the first version.