clemson77on Posted December 5, 2009 Share Posted December 5, 2009 I'm sure this has been covered on here, but I had no luck with a search for it. I'm trying to draw an arc to the tangent point of a circle but it goes to the inside when I snap to the tangent. I don't know what the radius is supposed to be. I just need the bottom quadrant of the formed arc to be at the top quadrant of the circle on the right. Quote Link to comment Share on other sites More sharing options...
eldon Posted December 5, 2009 Share Posted December 5, 2009 I think that you will find that there is no exact geometrical solution, so AutoCAD is doing the best that it can without exact information. You can find the radius of your circle, by successive approximation, but I don't think that AutoCAD can. Quote Link to comment Share on other sites More sharing options...
bradbb2005 Posted December 5, 2009 Share Posted December 5, 2009 Can you trim that piece off or is it needed? Quote Link to comment Share on other sites More sharing options...
CarlB Posted December 5, 2009 Share Posted December 5, 2009 I think you can do it with the "3 point" option- -pt1 is top quad of circle 1 (right) -pt2 is "tan" to circle 1, pick near pt1 -pt3 is "tan" to circle 2 Quote Link to comment Share on other sites More sharing options...
paulmcz Posted December 6, 2009 Share Posted December 6, 2009 I'm sure this has been covered on here, but I had no luck with a search for it. I'm trying to draw an arc to the tangent point of a circle but it goes to the inside when I snap to the tangent. I don't know what the radius is supposed to be. I just need the bottom quadrant of the formed arc to be at the top quadrant of the circle on the right. Draw vertical xline through center of circle B copy circle A by upper quadrant point to upper quadrant point of circle B draw a line from center of just copied circle to the center of circle A draw xline perpendicular to line connecting the two centers, through its midpoint Intersection of the two xlines is the center of the arc you want to draw See the attached sketch TangToCircles.pdf Quote Link to comment Share on other sites More sharing options...
Coosbaylumber Posted December 6, 2009 Share Posted December 6, 2009 We used to solve such without aide of Autocad, but after R-14 sometime found the tangent did not go "exactly" to tangent but to nearest point on the circle. I used to visit the Autodesk site and they said it happened by about R-2004 when they went to a M-S based calulation. None of the Reps. from Autodesk said there was any problem, and was zero complaints too. I had it investigated here, and got a few responces, as like it is used only once or twice per year by them too. You got the same problem as they have in Cheapcad now. I had to go back to my old pencil notes to solve the bad lines. Wm. Quote Link to comment Share on other sites More sharing options...
eldon Posted December 6, 2009 Share Posted December 6, 2009 Having just had a play, CarlB's method works in AutoCAD 2002. So full marks to the three point circle. Quote Link to comment Share on other sites More sharing options...
clemson77on Posted December 7, 2009 Author Share Posted December 7, 2009 paulmcz- Thanks! I was able to get that to work. Carl- I couldn't get that to work. I was probably doing something wrong, but I never got tangent options on point 2 & 3. Quote Link to comment Share on other sites More sharing options...
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