Modify and smoothing a Spline.

[kretallick144]

I have a Fit point spline i drew from a few fixed points. 

I have replaced some of it with new lines and blended them in but i cannot find a way to smooth the joins into one continuous line.   Tried the Blend command but no change.

Need this as smooth as possible for machining purposes.

[SaeedHamza]

First, you have way too many points for a fit spline, if it was a control point spline, the more points the more the result will match you goal while maintaining a smooth curvature. I have a script that I created to recreate multiple connected splines into a single control point spline, why control points and fit? again to maintan a smooth result.

For your case, the creation of your spline as a fit point spline is symmetrical, so it shouldn't have more or less than a specific number of points (in you case 8 points), take a look at the attached picture below and notice that all angular tangent handles are symmetrical and equal, the same goes for the horizontal/vertical handles. This way, you get a symmetrical and smooth curvature comp.

The correct way to draw this is to create a circular pattern of a horizontal line so that you get a line every 45 deg intersecting with a projected line from your geometry, by this you'll have 8 points to snap to when creating your fit point spline.

Please find the .f3d file attached so that you can take a closer look.

[kretallick144]

Thankyou. I will have a play and see how it goes.

What would be the best/easiest way to modify only a part of the curve,  Eg, a section increased or decreased in diameter but still creating a smooth line.

[TrippyLighting]

Quite frankly, I would start this completely from scratch. I've seen hundreds of such designs in my career spanning almost 4 decades. No engineer would ever us a spline for such a thing.

Maker sure to turn the timeline on 😉

[TheCADWhisperer]

@kretallick144 

What are you attempting to model?

Is this for a rotary engine or pump?

[etfrench]

You can use three point circles or arcs to easily reproduce the splines.

[kretallick144]

Yes for a Wankel engine.

I attempted to draw it using points plotted along the curve created by the rotor at the end points but in reality it isnt producing a consistent clearance.

[kretallick144]

So how would you do it?

Timeline vanished when i moved it to start another version.

[TrippyLighting]

I would sketch this with lines and arcs, just as @etfrench has described and just as @TheCADWhisperer will likely recommend.

[davebYYPCU]

Smooth, use Tangent arc coincident connections.

Might help….