# Is there no way of blending an Arc and Tangent line into spline

… without messing up the arc curve and the line straightness?

I know I can use RebuildCrvNonUniform and keep discrepancy between original and result under document unit tolerance, but I’m hoping there’s a way to just get rid of the kink where curves meet, so I don’t get this (exaggerated on purpose):

A higher-degree curve can’t exactly represent a lower-degree shape, you can’t draw a perfect arc with a smooth higher-degree curve. If you don’t want the curvature to do that on your rebuild, you have to tweak the points a bit, Rebuild is a pretty simple-minded tool that doesn’t care what happens to the curvature.

There’s a question of what you’re actually doing and why. If you need an “actual” arc, then work with that. If you want a smoother freeform curve, then…why are you working with arcs and lines at all?

I need it to be a continuous curve that will be a sub-curve of another curve, so I can pull non-varying radius dimension on the arc part and apply various edge conditions or pull subcurve dim on it.

So, I take it the answer is no.

I don’t really understand what you’re trying to do. You want the arcs to be arcs and the straights to be straights? So…why are you using Rebuild? Why are you trying to make it higher-degree? It’s not possible to get rid of the “kink” without changing the shape.

And Rebuild is a really dangerous command to use on curves or surfaces that you’re not intending to freeform point-edit.

I use RebuildCrv… right now 'cause that’s the only way I know how to “combine” an arc and a line into a single curve. I don’t care about what degree the resulting curve is. And I don’t need to use RebuildCrv if there’s something else I can use that doesn’t destroy an arc and a line.

Okay so what’s wrong with just joining them?

Because they will be joined to other curves and there’s no way to treat this arc+line segment as a single entity.

Well the ends of the arc have kinks in them, so no it’s not possible to merge those into a single curve without changing the shape. Definitely don’t go using Rebuild just for the sake of this, you’re changing the shape!

Our tolerances allow for slight 1/128"-1/64" discrepancy, so that’s quite alright for me to use that command. Just can’t stop myself striving for perfection… Thanks anyway!