Stock from Selection & 3 Axis Curve Machining

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We recently caught up with Max Allstadt, entrepreneur and independent CNC contractor out of Brooklyn New York. Max is an avid Rhinoceros modeler and has been using RhinoCAM Professional with his ShopSaber CNC router since 2017. This project is part of the stage for the United Nations 2019 Climate Action Summit in New York. 

The RhinoCAM Project

Max’s portion of the United Nations 2019 Climate Action Summit in New York included the stage backdrop and banner. Below you can see the curved “waffle board” frame assembly loaded into Rhino 6.0. The components that we will be studying today are the curved radii sub framework at each of the two upper corners indicated in the images below. What is interesting about these two sub frames is that they are 3-dimensionally curved in each X, Y and Z axes simultaneously. To achieve this cut Max used RhinoCAM’s Advanced 3 Axis Curve Machining strategy. The toolpath follows offset to the outer perimeter edge radius while being projected downward in Z onto the curved part surface! Max also utilized RhinoCAM’s stock from selection feature that allowed him to model his own unique in-process stock model to minimize machining time! 
On the left we see the “waffle frame” assembly displayed in Rhino 6.0 with the RhinoCAM milling plugin loaded. The RhinoCAM Machining Browser is displayed on the far left. On the far right we see the actual United Nations 2019 Climate Action Summit in process with the stage backdrop clearly shown. 
Very Cool!

The Machining Setup

The machining setup for this project includes just 3 operations. Two are 3-axis roughing and re-roughing toolpaths while the third is a 3-axes curve machining strategy. On the right you see the Machining Job tree. The setup “Carved Arcs” contains the 3 toolpath operations in question. You will also see that the stock is defined as “Stock from Selection”. See more information about the stock below. 

The Part Geometry

The geometry for this setup includes the part models, masking surfaces, stock models and stock definition. Image (A) below shows part models. You will notice the compound curvature by looking at the top outer edge of each part. Each part consists of multiple layers of ¾” stock. Notice that the parts contain hollow cores to reduce weight. In image (B) you will see that a masking surface is displayed on the top of the part. This surface masks the hollow cores providing an even surface for the toolpath to follow.



The 3D part models are shown in Rhino 6.0. You can see the compound curvature of the top of each part.

A masking surface is displayed on the top of each part to hide the hollow cores from being machined.

Stock from Selection

To save machining time Max has modeled his stock to match the actual stock that the parts will be cut from. In image (C) below you see the 3D stock models displayed. With the stock models selected in Rhino, you simply select “Stock from Selection” from the RhinoCAM Stock menu. This assigns the selected geometry as the current stock definition. After this is done, you then hide the actual stock geometry by turning off that layer in Rhino. In the image (D) you see that the stock definition matches the shape of the stock geometry.

Stock from Selection is a feature that is available starting with the Professional configuration of RhinoCAM. It is used anytime you have an irregular stock definition. For example, it can be used when the stock needs to match a casted blank. It can also be used anytime you want to minimize machining to a specific shape.
IMPORTANT: Make sure you hide the actual stock geometry after defining the Stock from Selection!

The 3D stock geometry is displayed in Rhino. It matches the actual stock placed on the CNC machine.

The “Stock from Selection” is displayed. Make sure you hide the actual stock geometry!

3 Axis Curve Machining

After using 3 Axis Horizontal Roughing and the Re-Roughing, the finishing operation in this setup is a 3 Axis Curve Machining strategy using a ¾” ball mill cutter. Curve Machining is another advanced 3 Axis strategy available in the RhinoCAM Professional configuration. In this operation the toolpath is offset from a drive curve and projected downward onto the underlying part surface. A cutting band width of 3.5” and a stepover distance of 0.112” (15%) matches the part width. The operation also uses straight cut connections between stepovers. The images below illustrate the operation. Note that the selected drive curves are at the top outer edges of the part. 


3 Axis Curve Machining is used to finish the top contoured surfaces of each part.

A drive curve and cut width determine a cut path that is projected downward into the top of the part.

More Shop Pics from Max Allstadt

Here are some additional shop pics from this project. Max’s ShopSaber 3 Axis CNC router is shown top left. This is followed by in-process stock material and the final curved frames installed. See more of Max’s projects here.

Here you can see the in-process production pics for this project from Max Allstadt.

Cool project indeed Max!
Thank you for allowing us to showcase your work!

More about Max Allstadt

Max Allstadt operates his CNC shop from within the Studio Guereux Fabrication for the Arts complex in Brooklyn, New York. Max specializes in exceptional quality and the on-time delivery of each and every project with the use of CAD/CAM and numerically controlled tools including Rhinoceros CAD modeling and RhinoCAM CNC software. You can find more pics from Max here on InstagramClick here to read the entire case study showcasing the work of Max Allstadt! 

Just a few projects from the shop of Max Allstadt!

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Don LaCourse

Don LaCourse

Don LaCourse is an Application Engineer with MecSoft Corporation. Don brings over 20 years of experience in CAD/CAM operations in both automotive and mold design applications. Don also has extensive experience in documenting CAD/CAM products and is actively involved with writing the on-line help as well as creating training tutorials for MecSoft's products.

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