# What is the difference between a Spine and a Guide curve in Sweep Command ? ( CATIA V5 )

If you could state a scenario that brings out the difference , that would be perfect! Thank in advance folks!

with spline curve, you will get the object as in certain ratio but with guide curve will get it as shape by the curve also there are the restrictions for curvature using spline.

In general.... because my Catia experience is a few versions old...

...within a sweep/swept feature, you may select up to 3 guide curves. Adding 'spine' curve selection gives you, essentially, a fourth guide curve to drive the final shape.

A good example is a boat hull. To make a swept surface representing the boat hull; curves at the upper edges and the keel would be Guide curves. A Spine is optional, but a centerline would be a good spine

As Jack Knapp has clearly put it. A very good description. These methods are taught also in our CATIA V5 Surfacing course and I pretty much describe it word for word as Jack.

Another way of thing of it... the spine in a sweep is the direction in which the profile remains normal to.

Whereas the guide curve defines the edges to which the profile follows.

The spine can be the limiting element to which a profile may be limited to on one "guide curve" than the other. This is common when two guide curves are in a different orientation and length with respect to offset.

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If u need a curvature at the upper or lower surface between two different profiles then u have to use spine and guides are used for defining boundaries between two different profiles.

A "spine" in CATIA is a curve (line, circle, spline, ellipse, axis, etc) that is used in many commands to define the orientation of shapes that are based on cross-sections. For the Sweep command, the spine curve defines the set of planes in which all the cross-sections lie of the swept surface as it transitions from start to finish.

A guide in CATIA is a curve that often defines the edges of the swept surface. Often there are two guide curves to define the left and right side of the swept surface.

Sometimes the same curve is used as both the guide and the spline. Sometimes different curves are used.

There are much better definitions and examples in the CATIA online documentation.