Double Tangent Arc

[Barneel]

I bet this is easy as pie, but the arcs just won't behave! I need an arc that is required to be tangent at both ends.

 

I've attached a picture that will hopefully help explain what I'm trying to do.

 

The red lines are the arcs, the green lines are the lines I want the arcs to be tangent with and the yellow dashed line is the point at which I want the arcs to end.

 

 

Thanks!

[PotGuy]

Don't suppose the Fillet command would work for you?

 

You could draw a circle with its centre being at the base of the graph, then select the end point of one of the lines on the graph and finally trim off either side?

Edited September 16, 2013 by PotGuy
Circle thought

[nestly]

If I understand correctly, the endpoints are different distances from the "center" so it can't be an arc. Ellipse with different X major and Y major radius perhaps?

[Barneel]

Potguy:

 

I wouldn't imagine so. Mainly because the arcs I'm trying to create won't have a linear radius due to their tangents, which will make them more of an oval

[SAFeSTeR]

I don't think FILLET will work if the x and y distances are different.

 

Perhaps you could try drawing ellipses using the point where the 2 dashed lines meet as a centre point then trimming off what you dont need?

 

EDIT: The quadrants of the ellipses to be placed at your required tangent points.

[Barneel]

Aha the ellipse idea is a good one! I'll give it a go

[Barneel]

Ellipse brilliance!

Thanks a lot!

 

[SAFeSTeR]

Ellipse brilliance!

Thanks a lot!

 

No problem, glad it worked for you

 

EDIT: Damn, thought I replied before anyone else, just noticed nestly's reply, grrrr

[Barneel]

It's the thought that counts...

[rkent]

Use the BLEND command.

[Barneel]

Another good suggestion. Interestingly it creates a different result with a slightly more harsh transition into the tangent. I suppose because it's goal is to reach the tangent and nothing more, as opposed to the ellipse which continues afterwards. But I still would have expected the same results

 

[rkent]

There are options under that command and you can pick on the vertices and manipulate the object. Just shows that there are lots of solutions that are all tangent to the two lines. You can add vertices by hovering over the blue circular grip, see other options there as well.

[Barneel]

Ah, "continuity", makes sense now I let it pass through my brain properly. Neat feature.

[merdrignac]

Use "Arc, start, end, direction".

 

Fillet the lines with zero radius, then use the angle formed to "pull" the arc radius to.

[nestly]

Use the BLEND command.

 

So I read that and said "What? ... that's not a real AutoCAD command!" but it works in 2012 and newer. Cool

[Barneel]

It's the kind of command you hear about and think... "Why have I not heard of this before"