How to dimension spline pins?

[ianbarcellos7]

Hi, I'm just getting started with Fusion and I have no idea how to find the spline pin dimensions for the sketch im making.

If anyone could help I just need to know how to find out the dimensions of the green circles shown in the picture 

[Drewpan]

Hi,

Spline pins are really much like any other geometry when it comes to constraining them. It is just that due to the

nature of splines they tend to be at odd angles and differing lengths and that sort of thing. It is possible to lock

down a spline, it just normally takes a while and one of the biggest reasons why the forum recommends that with

splines - less is more. Keep the points to a minimum so that you can lock them down and you usually get a much

better result with fewer of them.

Constraining a spline is typically done by dimensioning a length first and then giving it an angle relative to

something else in the sketch. If you are lucky you might get away with that but often you also have to dimension

the points at the ends too. LOTS of work. Treat each individual spline point bar as any other line. You can put vertical

and horizontal constraints on them like other lines. You can also make them co-incident if you need to.

Good luck

Cheers

Andrew

[g-andresen]

Hi,

With a fit point spline, each control point requires a position definition in 2 axes and a definition of inclination and length for the tangent, i.e. a total of 4 definitions.

According to your screenshot, only one instance would need to be created in the sketch. The duplication takes place as a solid feature.

Please share the file for reply.

File > export > save as f3d on local drive  > attach to post

günther

[TrippyLighting]

The green circles are only a visual aid to judge the minimum radius of the fit-point spline at the fit-point.

They cannot be dimensioned separately, although, that would indeed be an excellent feature request!

[ianbarcellos7]

Here's the file, not sure why I didn't attach it in the first place. 

I just need the radius of the smaller set of male splines to be 6.77mm and the radius of the female splines to be 6mm.

(in the file one of the circle/spline sets is 0.77 mm smaller)

It's a tapered spindle for a bike crank. I have the correct size tapered end mill, If I were to CNC the shape I assume I'd only need to know the lower(smaller) spline dimension as when I create the tool path the end mill would cut the upper (larger) spline to the size I need it to be? I think I'm just overcomplicating this for myself but I don't have any experience to know what matters and what doesn't matter...

[TrippyLighting]

I would not use a spline for this. Arcs and tangent lines should suffice.

[ianbarcellos7]

How would I make arcs and tangent lines that create that same shape? 

[g-andresen · Accepted solution]

Hi,

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@ianbarcellos7  schrieb:

How would I make arcs and tangent lines that create that same shape? 

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this way:

günther

[ianbarcellos7]

Thanks so much! Can't believe how simple it was in the end, and how many people came to help! Very excited to start machining!