While reworking our compressor blade design, I needed a slick way to extend my geometry, and found Solid Edge’s Extend Surface Tool to be a very clever asset.

## The Problem

I need to be able to affect the blade design at key points, specifically designed according to region of fluid flow they affect. The design planes for these locations are normal to the blade axis, however the case liner and hub are curved. I need the blade ends to be concentric to the axis of the compressor. Trimming the solid blades to final length is a good way to achieve the desired result, but poses a distinct problem. The blade twist, shape, and casing taper make it quite difficult to sweep a solid that can be trimmed by an intersecting surface, one that will completely intersect each blade’s cross-section.

No worries, Solid Edge’s Extend Surface tool will do the trick.

## Surfaces are the Solution

I do not like to do work with surfaces, however I find them to be repeatedly invaluable. Solids, designed in ordered mode, cannot be extended without a lot of steps, and will not continue a complex shape. Surfaces, on the other hand, can. Our blade design includes swept surfaces, along an axis, and through multiple planned cross sections. The blades, as mentioned above, come up short of the surfaces they need to contact in certain areas.

Solid Edge’s Extend Surface Tool does just what the name implies, it extends surfaces.

1. Pick the Extend tool on the Surfacing interface.
2. Pick the surface edges to extend.
3. Indicate the extent of the extension.
4. Accept the result

Options are available to terminate at another surface, or to enter a finite distance. The extension methodology can be one of the following:

• Linear – a straight extension, tangent to the existing surface curvature
• Curvature Continuous – continues the curvature that was existing before the extension
• Reflective – creates a “mirrored” extension of the existing surface shape

Users can extend multiple edges of a surface simultaneously. In this example I show only the upper edge of the blade selected, however both edges can be extended.

## Conclusion

I could have used my hub and liner surfaces as references to extend into, which is a great option in many instances. In this case, the only way to ensure the ends of each blade are precise would be to make the extension to said reference surfaces, and then cut an intersected end cap from each reference surface. This is a time consuming, and complex workflow. By using Solid Edge’s Extend Surface Tool with the Curvature Continuous option, I can extend the precise blade shape and twist, an arbitrary distance. Later, after stitching the surface into a solid body, I can trim the solid to the precise length and shape. It’s not the only way to do it, but it results in less steps, with less complexity to rebuild as we alter variables (parameters) later.