CAD-CAM Tips & Tricks | Surface Machining

Posted July 12, 2018 3:03 pm   Published by    BobCAD-CAM ">

If you’re machining 3D parts, I’m sure you’ve run into the following scenario. You have a curved top surface to your part and there are voids along the surface area.
surface machining in BobCAD CAD-CAM software
If you try to machine the part as is, your toolpath ends up dipping down into the void areas, which you don’t want.
toolpath on part in CAD-CAM
Also, you notice the toolpath isn’t extending past the edge of the part, which you really need it to do to create a fully machined top surface.
If you’ve designed the part in BobCAD’s CAD-CAM system, you can use the CAD history tree and suppress the void features. Eliminating them from the design, therefore, the tool would not dip down into them.
CNC software extrude cut function
Using the CAD history tree is a fast way to remove part model features that may get in the way of machining.
An alternative method is to use an offset surface. This may require you to unstitch your solid to surface first. Once you can select the top surface only, you can create an offset surface at a zero distance.
BobCAD-CAM's CAD-CAM software feature: offset surface
top of part in CNC software
Using an offset surface at a zero distance gives you a copy of the surface at the top of your model.

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Your next step is to untrim this surface. Using untrim, all the “holes” in the surface will be removed.
part without void in CAD-CAM software
Now that you have a single surface with no voids that when you apply your toolpath to it, the tool will not drop down. Instead, you get a very nice clean surface with a great finish.
toolpath on top of part in BobCAD-CAM's CAM software
You will notice that the tool center is right on the edge of our part. So, if you wanted to extend the toolpath, what can you do? Using extend surface, you can select an edge of our newly created surface and extend it.


This allows you to drive the tool past the edge of the part. You can extend the surface on all edges to make sure the top surface of your model is fully machined. Isn’t that simple? Give it a shot yourself!

To learn more additional tips and tricks when surface machining, download a demo of BobCAD V30 and schedule a one-on-one screen share. Our software experts and walk you through the process and help you evaluate if using offset and trimmed surfaces for your part manufacturing is the best choice.

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Article Name
CAD-CAM Tips & Tricks | Surface Machining
If you have a curved top surface to your part and there are voids along the surface area, follow this CAD-CAM tip to avoid toolpath dipping in unwanted areas.
BobCAD-CAM Software

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