The CNC Experience - Building a Curved Front Cabinet (Week 2)

Step Four - Mill the straight and curved moldings for the base and top of the cabinet.

The first step in creating the curved molding along the font of the base and top of the cabinet was to draw the curve in my CAD system.

The drawing above shows the base with bracket feet.  I'll use the line at the front of the molding to create my tool paths in Aspire.

Above is the multi-profile router bit I used to create the bull nose and cove details.  I'll only be using the top half of the bit for this molding and I'll use the same bit to create the straight moldings for the sides of the cabinet top and base.

To avoid having the bottom half of the bit drag across the table of my CNC I built a fixture that spaced the material up off the surface of the table 1.25" and then clamped the material securely with one top clamp on each end of the stock.  Next I created a new bit in the Aspire tool library.  I was unable to get their form tool gadget to work and create a custom tool with this exact profile so I created a straight bit with a 1.1" diameter and too cutting length of 2.25".

Above you can see how I determined the cutting diameter of my custom bit.  In the tool library setup page you can set the cutting depth for each pass.  I set this to the total length of the tool because I needed a router bit to go to the right depth and then plunge into the material from the side, not from the top.

I decided to cut the curved profile in several passes each 0.2" deep.  To create the tool path I imported the drawing of the curve along the front of the molding and used the offset tool in Aspire, (VCarve Pro has the same tool), to create several lines that followed the curved line of the molding.  I also added a lead-in line at each end of the profile so the bit would start the cut 1" away from the material and move 1" away at the end of each cut.

In the screen shot above you can see the enlarged view of the beginning of each pass with the lead in line.  As you can see it tool seven passes of 0.2" deep to produce the finish profile, the last pass must be 0.2" deep in the stock in order to just clean up the outside of the arc.

Above you can see the full screen shot with the details about the cut.  I se the machine vectors parameter to "on" the line.

Above is the setup to mill the curved profile on the right and the straight section on the left.  It tool only four passes from the side to complete the straight molding.  You'll see that I'm using a 2X6 for the prototype so I had enough material to flip the stock around and mill a second profile on the opposite side.

Just a few more notes on the setup process.

You must change the "plunge depth per pass" of the tool you create in the Aspire tool library equal the length of the cutting face on the router bit you plan to use.  If you fail to make this change Aspire will make several cuts on each tool path at the pass depth set on the tool setup page.  This will, of course, ruin the look of the molding.

After using the offset tool to create each pass I used the preview tool path feature to make sure that my last pass just trimmed a bit of the face of the material at the high point of the arc.

On the straight molding pieces you can simply mill or plane the stock to the correct thickness and then mill the molding profile.  You can then cut away the waste to create the proper width for the final molding.  I cut the molding to the proper width on my table saw with the bull nose part of the molding against the fence.

To cut the curved molding to the final width the stock must be run through the table saw with the flat edge of the stock against the fence.  This edge must be straightened before you begin the milling process so it fits flat against the fixture and the saw fence when you trim it to size if you want perfect miter joints on your chop saw.

Step Five- The cabinet sides.

The cabinet sides are milled on the CNC as well.  After drawing the parts, complete with rabbets and dados, I imported them into Aspire to create the tool paths.  I added additional lines to the dados and rabbets so that the tool paths extended beyond the panel so that the dados and rabbets were cut cleanly.

I won't bore you with more picture of cutting the shelf panels to size of the assembly of the cabinet.

Next Week

Next week I'll build the curved and raised panel door for the cabinet.  Until then, happy woodworking.

Andy Anderson

Comments

[Shelena]

It's hard to make a curve wood by man made/Manually made. Thanks for the new technology its now operate with robotic something that will make what you want before that you must program it before running this.

Shelena | Compliance Posters