topic Re: Perpendicular-to-tangent constraint? in Fusion Design, Validate & Document Forum

Perpendicular-to-tangent constraint?

JetForMe — Sat, 27 Dec 2025 01:19:28 GMT

Is there an easy way to constrain a line to be perpendicular to a curve at a point? I found a cumbersome way, with two lines, two points, two coincident constraints, and a perpendicular constraint, but that's very cluttered. I need to make a number of such lines, and don't know of a simpler way.

Re: Perpendicular-to-tangent constraint?

TheCADWhisperer — Sat, 27 Dec 2025 01:39:03 GMT

@JetForMe

There might be.

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

(If your actual file is proprietary - simply make up a dummy file that exhibits the same behavior.)

Re: Perpendicular-to-tangent constraint?

jhackney1972 — Sat, 27 Dec 2025 01:39:41 GMT

Take a look at the video. You will end up with multiple sketches but the method is easy.

(view in My Videos)

Re: Perpendicular-to-tangent constraint?

davebYYPCU — Sat, 27 Dec 2025 01:42:48 GMT

... a line to be perpendicular to a curve at a point?

Sure, draw a line from curve to it's centre point. (Radius line)

There are a few workarounds for Splines, but more context is needed for which one to use.

Might help.

Re: Perpendicular-to-tangent constraint?

TrippyLighting — Tue, 30 Dec 2025 12:59:21 GMT

@JetForMe wrote:

Is there an easy way to constrain a line to be perpendicular to a curve at a point?

Arcs show with a center point, and you can make a line perpendicular to an arc by using the coincident constraint between the line and the center point of the arc.

It's perhaps not as intuitive as a perpendicularity constraint, but it works the same effect.

Unfortunately, tangency, or perpendicularity to a spline curve, still requires workarounds.

Re: Perpendicular-to-tangent constraint?

MichaelT_123 — Wed, 31 Dec 2025 06:45:31 GMT

Hi Mr JetForMe,

###

The theme "Tangency and Perpendicularity to Spline at Point" ... is popular on this Forum, like 'Dark Side of the Moon' by Pink Floyd. It is timeless.

###

This is the excerpt from:

https://forums.autodesk.com/t5/fusion-design-validate-document/tangency-and-perpendicularity-to-spline-at-point/m-p/12514506

There are some more or less viable approaches to the conundrum posted already.

Please find another one below. I am not sure whether it has worked in previous Fusion sketch machinery, but it seems quite a natural, friendly solution now, but ONLY for 2D spline/sketch. For the 3D scenario, “a planeOnPath” is a viable solution.

What to do:

Draw a spline
For the existing one, insert a fit point where you want your line segment to be perpendicular
In the sketch trigger spline’s tangential handlers
Apply a perpendicular constraint to the line and the handler at the fit point of interest
That’s ALL

How to test:

Drag the fit point
Drag and end of a tangential handler (changes its angle in 2D)
Drag the line itself (by position and/or angle)
That’s ALL … I can think of!

The simple test file is attached.

Have Tangential_or/and_Prependicular 2026

MichaelT