Remove Bevels easily (without using untrim) -- working with step files

Hello everyone,

I have a file imported where I need to optimize some parts.
To make my workflow easier I would like to dissolve all the fillets.

Is there a fast way to do this, if all fillets are perfectly round fillets?

Thank you for helping!

No, not in Rhino because they are surfaces.

It might very well be possible in in originating application if the fillets/chamfers are “features” that can be edited. This is typical in parametric, feature based modeling applications.
Once it’s exported to STEP, they are no longer editable features and have to be manually edited.

Several years ago I tried SpaceClaim and one rare feature it had was the ability to detect and remove round fillets from imported NURBS models.

Yes, there are several applications that support what they call “feature recognition”. Then importing the STEP file and running those tools might find and remove some of them.

I used Spaceclaim as well shortly after it became available. Worked well for simple stuff but also often failed to extend more complex surfaces. Extending surfaces is not always obvious and it was hard to see what it was doing. It often generated very heavy garbage surfaces, but the problem was you would find that out too late in the process.

The “feature” that those applications recognize is called an “Arc”.

It is an absurd belief that Rhino can’t recognize arcs and Rhino can’t recognize when surfaces that are based on arcs are tangent to the neighboring surfaces such that the arcs are perpendicular to the surfaces on both ends of the arcs.

Recognizing fillets is dead simple. Any competent Rhino developer should be able write the code for fillet “feature recognition” in about 20 minutes.

The problem with removing fillets is not the “feature recognition” part. Even the Rhino users can handle that part of the problem. They know which surfaces are fillets even if McNeel remains clueless.

The problem with removing fillets without a history of how they were created is that often when the fillets are made some of the surfaces that existed before the filleting are completely consumed by the filleting process. Without any knowledge of what was there before the fillet was made it is difficult to recreate the the object that existed prior to filleting due to the missing surfaces.

The problem with removing fillets should be really pretty simple for fillets made by FilletEdge (rolling ball version) command. The FilletEdge command never ever ever consumes any surfaces (this is why it is such a lousy algorthm). What that means is that after getting rid of the arc based fillets you should always be able to untrim and then retrim the base surfaces and always easily recover the original geometry.

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Maybe Analysis Situs can help.
For example, enter recognize-blends in the Active Script panel, then click Defeature faces in the Modeling tab.

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