TTR lisp creation

[SAPER59]

I need to create inside Lisp a TTR circle to use as fillet arc between a line and an arc

The point is that when the convexity of the arc changes (try to go far from line end point) the arc is created to the other side, extending the line, when I make a FILLET with R=3

The only way I found is create a TTR circlle, and then trim or break the portion outside intersection objects point

Thanks in advance

[SAPER59]

Thanks, it works

[ВeekeeCZ]

@Rick_Tolleshaug_TSC 

Nice code, thanks for sharing.

btw it's DIESEL...

[Rick_Tolleshaug_TSC]

Glad to see PLFILLET worked for you.  Here is an updated version with the following changes:

1. Now highlights first segment, not entire polyline (consistent with native FILLET command)

2. Better maintains individual segment widths (when objects have no Global width)

3. More predictable layer results

[Sea-Haven]

I tried the code with 2 arcs and went round in circles with it asking for 1st and 2nd object radius etc but it did draw a 3rd arc, ok the problem I used a large radius so wanted an outward based 3rd arc, the code only produced an inward arc, when using circle ttr got an external circle the desired direction. 

I am sure your code will produce correct answers for particular situations. Autodesk really needs to look at the fillet command considering we are 40 years later since Autocad was made and the problem is still there. 

Will try to find the user manual form the 80's where a civil package solved this problem.

[Rick_Tolleshaug_TSC]

I think I understand what you're eluding to, based on your image showing outward tan-to-tan arc at the top and inward tan-to-tan arc at bottom.  I recognize AutoCAD provides no easy way to create the outward tan-to-tan arc. This is a situation, as you know, where radius is unknown and depends on location of tangent points. Conversely, FILLET-R and CIRCLE-TTR the radius is known and specified by the user.  Therefore, I see these as different tasks.

I know you weren't looking for LISP routine, but it wasn't difficult to create one that will draw an outward tan-to-tan arc.  Attached is OTTA.LSP (command: "OTTA") which is rough, not in any finished state.

Command Steps:

Given any pair of circles, arcs or combo, with identical radiuses, positioned horizontal, vertical or at an angle...

1. Select pair (wants a selection set)

2. Specify tangent point along circle or arc keeping in mind that arc will be drawn counter-clockwise (only supports this direction currently)

If I were a programmer at Autodesk and wanted to integrate this into AutoCAD, I would look at adding command option Ttp (tan tan pair) to the ARC command.

[Sea-Haven]

Thanks for replying I have some ideas about doing this. Using circle ttr but trimming the circle and trimming the ends of the 2 touching arcs.  Will try to find the old like a year ago prior post.