In this video, I take Popular Woodworking readers on a tour of my custom 38″ x 72″ x 10″, twin-spindle CNC.
Over the last few years, I’ve written several articles and dozens of blog posts for Popular Woodworking Magazine. I often include photos of my own CNC. Because my machine is a bit unusual and not exactly “off-the-rack”, it’s captured the attention of a number of readers and generated a lot of comments and inquiries. So, before I begin a new series of posts on modifying CNCs, it’s a great time to introduce you to my custom CNC.
Why a Custom CNC?
The world of CNCs covers a huge range of sizes, capabilities, uses and price ranges. Since CNCs are used in several industries, they come in lots of forms. For woodworkers, we have some excellent small, desktop-sized CNCs from builders like Shapeoko for under $2000, larger, more powerful and capable small shop-sized machines from Laguna and Axiom Precision, and if you have the room and the budget, cabinet shop scaled machines are available from scores of vendors.
When I started using CNC services to machine the patterns for my furniture in the nineties, I relied on a service in Seattle, Davis Sign Company. With their industrial grade 5’ x 10’ CNC and powerful vacuum hold-down system, it’s well suited for cutting the MDF that I use for my patterns. But, as I began to consider a machine for my own shop, I knew I’d need something different. I came up with a list of needs and requirements better suited to cutting and carving wood.
Sized for a small shop
At around 1800 square feet, my shop is fairly small — at least when it comes to dedicating the considerable space needed for a large CNC. I’m a furniture maker and my uses for a CNC are different than a cabinet maker so, the common 4’ x 8’ CNC with a low, 3″ Z height is not a good fit. In my work, I need a machine big enough and powerful enough to cut hardwood furniture parts and occasionally mill flat material like plywood.
What is a good size for a woodworking CNC? A good rule of thumb for sizing the capacity of any fixed tool in your shop (table saw, joiners, planers, large sanders, etc) is to measure the largest parts that you’ll machine and size accordingly. Think 85-95% of your regular maximum size needs, not 100%. For example, buying a wide belt sander for that once-in-a-lifetime 48″ slab table you might build someday is not being realistic. Every professional woodworker I know farms out large or specialty machining to a service.
So, be practical. For the 5-10% of the parts that are too large for your machines, use other woodworking methods, techniques or even services. Remember, dealing with special needs and situations with your skill and experience are all part of the fun of woodworking.
For example, some of the furniture parts I make are 8’ long, but the majority I produce are under 6’. So, I figured a maximum length of 6′ would be fine for my CNC. For width, hardwood parts aren’t very wide, but I wanted a CNC wider than 2’ so I could mill large slabs, cut plywood sheets or cut multiple parts at once. I would have liked a 4′ width, but with limited shop space, I settled on a 3’ width.
I chose a useable Z, or vertical height, minimum of 10” because I do a lot of 3D carving on my CNC and often machine very thick wood. I also added what’s referred to as “over travel”. What this means is the spindles to extend beyond the length of the bed so I can machine parts held vertically for joinery, for example.
And, I chose two spindles rather than one. Why? Well, good quality automatic tool changers are very expensive, but a second spindle was not. With two spindles, I can load up two mills or bits and do two sequenced processes in a single routine. Rough cutting and final cutting, for example.
I had other requirements. I wanted a highly accurate, fast and rigid machine for the precision 3D carving I had in mind. For that, it takes a heavy-duty structure and rigid gantry, beefier components, and a bigger and faster precision drive system. Note that I did not include a built-in vacuum system. As a furniture maker, I mostly machine small parts and vacuums don’t securely hold small pieces very well. With a heavy, 1/2” thick aluminum bed and my added custom grid/holding/registration system, I’m able to securely clamp and position any size part anywhere on the table.
A Custom Solution
My machine was built in 2014 when there were no CNCs available that fit my criteria. So, I chose to have my machine custom built to my specifications. I went with a well known local custom CNC builder in the Seattle area, Carl Bruce. Carl has been building custom CNCs for 25 years and built several woodworking friends’ machines so it was an easy choice. Four out of the five of the woodworkers in the Popular Woodworking December 2017 article on Digital Artistry have custom Carl Bruce machines. After we worked through my specs and wish list, he set about building it. A few months later, I installed the CNC in my shop. The result: nothing has been the same, since. Having a capable CNC of my own has had a major effect on the methods, scope and even the direction of my work.
Though my CNC has worked out great for me, a custom solution is not for everyone. A machine like mine is not less expensive, it costs a bit more than the machines you’ll find at a woodworking store. But, I get a lot in return. It’s well suited for my particular needs and limited space, and it’s incredibly robust for a machine of its size. It’s really a small, industrial grade CNC that’s powerful and very fast. The large-scale 3D carvings I make take a lot of machine time. Two or three days are common. Sometimes even longer. On my custom CNC, I can fly along at 3-400 inches per minute when many machines top out at 1-200 IPM. For me, at least, speed and power really help.
Evaluate your needs
Since 2014, a number of new CNCs have appeared that fit the needs of most digital woodworkers, so you may not need to consider a custom solution like mine. Bigger, faster and custom are not for everyone. But, no matter what direction you go when considering a CNC, I urge you to carefully evaluate your current and future needs before you purchase either a ready-made machine or consider custom. Don’t just settle for a tiny CNC today that can only machine small items like boxes and small carvings. Think about all the things you could eventually do with it. Like other fixed woodworking machines such as a table saw, a planer or a jointer, a CNC should be considered a long-term investment and if you select a well built one suited for the tasks you have in mind, it will be a long-lasting tool.
In the future, I’ll get into more details about my CNC and go over the many modifications I’ve made that make it easier to use, faster to set up and even more accurate. It’s a big list. If you already have a CNC, some of these ideas and tweaks may be applicable to your machine and just might help you get even more out of it.