Spline definition - similar handles produce very different curves

[kevin_bates4]

Hopefully this description of my issue is clear. I'm having some consistency issues with splines. I'm designing an exterior and interior rail, and each rail is a 2-point spline. The control lines for the spline are similarly constrained (the 2 start points are parallel, only offset by a small distance, same with the endpoints). But for some reason, the interior rail has a longer arc length for some reason? I wish arc length was something we could define in Fusion360 (like in Solidworks) but as far as I know, I cannot control this. I've attached a screengrab showing the issue I'm having. Thanks in advance for any guidance! 

[TrippyLighting · Accepted solution]

If you use control point splines you won't run into this issue.

In Fusion 360 The scaling of tangent handles for fit point splines is unique to each spline. they might start with the same geometry, but after some editing, even with seemingly identical handle length they might become different. 

It is also very likely that the implementation of fit point splines in SW and Fusion 360 is very different.

In Fusion 360 a fit point spline is a 5-degree multi-span spline. 

[kevin_bates4]

I see, thanks for the info, I'll try to use control points!