Manipulate fillet surface cross section and continuity

Use the controls in the Surface Fillet option window to control the shape (cross section) of a fillet surface.

Choose Surfaces > Surface Fillet ❒ to show the fillet control window, then click the Advanced tab.

Use a circular cross-section with lead in

Use a lead-in cross-section with bias

Set the Section Type to Bias and turn off Variable Fillets.
Set the Tangent Offset.
Tangent Offset is the distance between the intersection line of the two sets of surfaces and the contact lines (the lines along which the new fillet surface touches the surfaces on either side).
Set the Specify option to the lead distance variable you wish to use, either Peak Radius or Knee Ratio.
Since the two numbers are two different ways of measuring the lead distance, it does not matter which way you prefer to specify it.

Knee Ratio is the ratio between the peak radius and the tangent offset distance. Knee ratio = peak radius divided by tangent offset.
Use the Bias Factor option to control which side the peak is closer to. 0 is centered. Negative numbers bias toward the first side. Positive numbers bias toward the second side.

Use a circular cross-section

Use curvature continuity

Set the Section Type to Curvature and turn off Variable Fillets.
Turn on Use Peak Curvature.
Set the Specify option to the lead-in variable you wish to use, either Peak Radius or Peak Ratio.
Since the two numbers are two different ways of measuring the lead distance, it does not matter which way you prefer to specify it.

Peak (Radius) Ratio is the ratio between the peak radius and the tangent offset distance. Peak ratio = peak radius divided by tangent offset.
Use the Curvature pop-up menu to choose whether to enforce curvature continuity on both sides or only one side (the other side will be tangent). See the section Troubleshooting trimmed surfaces for more information.