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Thursday
Jul282011

The CNC Experience - Building a Curved Front Cabinet (Week 1)

 Why CNC?

Over the past few years, as I've urged woodworkers to consider adding CNC equipment to their workshop, I've heard objections like these:

  • CNC routers are only useful for processing sheet goods.
  • CNC systems cost too much, I wouldn't get a good return on my investment.
  • I don't have the computer skills to run a piece of CNC equipment.
  • I already have a shop full of great equipment, the perfect shop in fact, why do I need a CNC router?
  • Automation is the enemy of creativity; I don't want my projects to look like they came out of a cookie cutter.

The CNC Experience

As I think about the best way to answer these questions I always come to the same conclusion.  You have to experience CNC woodworking to really understand the advantages, the power, and the pure fun involved.

My Qualifications

First, let me say that I'm not an expert furniture designer or a world renowned woodworker, or even an author with several successful woodworking books in print.  So, why am I writing a column on CNC woodworking?  I know CNC equipment and processes.  For the past 30 years I've used many different types of CNC equipment and CAD/CAM software to solve manufacturing problems and produce profits.

Purpose of This Column

Obviously, the very best way to experience CNC woodworking is to come to our factory and test drive a Legacy CNC woodworking system.  Nothing beats real "Hands-on" experience; however, not everyone can make the trip to Utah, so I'll endeavor, in this column, to share the experience with you in print form.  To do this I'll be building a series of projects.

What is Involved in CNC Woodworking

Before we start on the first project we need to take a look at the entire CNC manufacturing process.  CNC operations can be broken down into three steps:

  1. CAD - The process of creating a complete drawing of your project.
  2. CAM - the process of turning your drawing into instructions for your CNC equipment.
  3. Setup - the process of getting the material setup in your CNC equipment and ready to process.

Note: Some software packages combine the drawing program (CAD) and the computer aided manufacturing (CAM) programs into a dual purpose package.  These are referred to as CAD/CAM programs.

Don't let thie list intimidate you.  If you can send an email to your family and friends or sort and file away your digital photo collections, you have the computer skills to get started.

CNC Classes

To help you polish your computer, CAD, CAM and setup skills, Legacy offers live, webinar style, training sessions each week.  If you see something that you don't understand you can join one of these classes to ask your questions and get your answers.  Follow this link to see the class schedule.

Project One - Curved Front Cabinet

As you can see from my plan my first project has a re-curved front.  The trim on the base and top and the door front follow a re-curved line.  The cabinet sits on bracket feet and this is where we will begin working on this week's project.

Step One - The Bracket Feet (CAD)

The drawing shows the foot, an end view of the contour on the face of the foot, and the shape of the finished foot.  I created this drawing with a CAD program.  (I use a three dimensional modeling program called inventor but if you are just getting started you can create the same drawing with TurboCAD 2D for under $40.00).  Chris Anderson teaches our online TurboCAD classes.

Step Two - Preparing the Code (CAM)

I built the bracket feet in two steps, milling the contoured face and then cutting out each foot, one as seen in the drawing and one, a mirror image of that foot.  I used Aspire, a 3D milling and carving CAD/CAM program to create the program.  Aspire has a simple tool called a two rail sweep which allowed me to import the end view of the bracket foot and create a three dimensional tool path along the surface.

I used a 1" diameter ball nose (core box) router bit with a 0.040" step-over.  That just means that each time a cut was made along the face the router was moved forward 0.040" and an adjustment made in the cutting depth before another pass is made.  (This technique is mostly used when carving a 3D picture or graphic but I like it for more practical jobs like milling a short run of custom molding.)  John Hennen teaches our online Aspire classes.

Next I imported the face view of the foot and created a profile tool path.  A profile tool path is simply a cutting path that follows a line.  It can be on top the line or inside or outside of a group of lines that make up any geometric shape.  Aspire allows me to control he amount of material removed each time around the line.  I chose to cut 5/16" (0.3125") deep each time around so it tool several passes to cut completely through the material.  Aspire has another great feature called tabs.  That means that a small web of material is left behind in two or three places to hold the part in place until the cutting is complete.  I used tabs that were 1/2"(0.5") wide but only 3/32" (0.09375") high.  These were easily removed after all the cutting was done.

Step Three - Miter and Rabbet

These steps were completed on my chop saw and my table saw.  I want to be able to add the feet to the cabinet after it is all finished so I glued and screwed a triangle of 1/2" plywood for stability and easy mounting later.

Next Week

Next week I'll build up the sides of the cabinet on my CNC router table and then I'll show you how I created the re-curved molding for the top and base of the cabinet.  After the cabinet is assembled we will move onto week three, the re-curved and raised panel door.

Until then,  happy woodworking

 

Andy Anderson
Legacy Woodworking Machinery

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Reader Comments (1)

Thanks Andy for the info on the project you are working on.
I started to read week one and I had to stop and kind-a laugh. I too, was one of those who thought of all those reasons why not to have a CNC instead of thinking of all the reasons why to have a CNC. I have been woodworking for many years. I am, by no means an expert either. However, I love creating things out of wood; the more complicated the better. I have a shop (I should say my two-car garage) full of tools, and those tools did get me by. However, the more I looked into the CNC, and the capabilities it would give me, the more excited I got.

I started to look more into getting one. Now, I did not go out the next day and get one. I just bought a used legacy 900 last November. I watched the videos, and started to make stuff. I quickly became convinced that Legacy had a great concept. By this time, my attitude towards CNC was changing quickly. It was not until I got an order to make 50 chair spindles that really convinced me to get a CNC. I did each spindle on the 900, and yes, I did crank on the handle for all 50. I could have done them on the lathe, but they had to be perfect at the ends so they would fit in holes of the chair. I have since gotten orders to make more legs, feet, and spindles.

By this time, I knew it was time to get a CNC. I shopped around, but I knew that the Legacy CNC is what I wanted. The first time I called, I think I talked with John Hennen. John suggested that I get the Mini-Arty to start out with, however, I knew that the legs and spindles were longer than 18” I also knew that I would love the CNC and wish I gotten a bigger one. Therefore, I did not get one then. My thinking was that I would get one in November when they would go on sale (black Friday) like last year.

I called one day in May and spoke with John, he said they were having a sale on the CNC that month and he gave me some numbers that I could work with. I used money out of my 401k. So in May of this year I became a proud owner of an Arty 58  (I know I should get a bigger one but my shop/garage would not handle one ) . I should get it at the end of this month.

If you are reading this and you still have not gotten a CNC let me share with you my thinking before I got one. First, you should know, that just because you have a CNC does not mean you lose your creativity; just the opposite, it will enhance your creativity. Second, you use all your different shop tools to create something out of wood. Meaning, you set your table saw fence say one inch from the blade, and you cut many pieces of wood the same size, guess what you just became automated in a sense. Third, you set your router or shaper up with a bit, and you profile many pieces of wood the same way, again, you have become automated. Fourth, have you ever cut so many pieces of wood the same way that you get tired, and your mind starts to wonder a little and you have one of those narrow escapes? These are just some of my thoughts I had that help me make a decision to get a CNC. I do hope this helps.

No, I was not paid to write this LOL I just know that a CNC is the way to go.

Thank you Legacy for your innovation

From a fellow woodworker
John Rogers

August 15, 2011 | Unregistered CommenterJohn Rogers

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