JET5 Posted October 23, 2008 Share Posted October 23, 2008 I am trying to reverse engineer and generate a drawing for a gear form. I have a radius at the root of .250, and a radius at the top of .350, and a radius between then of 3.25. I know the position and centerpoints of the first two smaller radii. But I do not know the centerpoint and tangency of the large radius to them. I tried to connect them using the tan-tan-radius command, but the radius it generates is a concave radius. I need a convex radius to tangent these other two circles. Anyone know how to get tan-tan-radius to make a circle in the other direction or from other points on two circles? Or is there a different way I can do this? Thanks, -Jet Quote Link to comment Share on other sites More sharing options...
RobDraw Posted October 23, 2008 Share Posted October 23, 2008 When you pick your snap points, place your cross hairs on the outer sides of the circles. Quote Link to comment Share on other sites More sharing options...
eldon Posted October 23, 2008 Share Posted October 23, 2008 It all depends on where you select the circle for the tangency. The nearer you can touch the two circles at the hoped for tangent point, the better. You can get different results depending on the steadiness of your hand. Quote Link to comment Share on other sites More sharing options...
JET5 Posted October 23, 2008 Author Share Posted October 23, 2008 Okay that worked, just had to keep selecting different parts of the circles until it changed it's slope. Thanks so much for the help guys. See attached image, the red line shows what I was getting, the green mirrored tangents show the completed gear form after several attempts. Still, it seems like there should have been a command to flip this thing. Inverse tangent or some such. Anyway, again thank you very much (who would have thought to just keep trying). -Jet It all depends on where you select the circle for the tangency. The nearer you can touch the two circles at the hoped for tangent point, the better. You can get different results depending on the steadiness of your hand. Quote Link to comment Share on other sites More sharing options...
BIGAL Posted October 24, 2008 Share Posted October 24, 2008 Our old civil software gave you the option of choosing the correct curve answer. For the circle rad circle there are actually 4 answers that match geometrically. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.