Tool Reviews (+Hot New Tools): A CNC lathe made from plywoodComments (0)
This article is from issue 112 of Woodcraft Magazine.
A CNC lathe made from plywood
PRICE: $1245, bobscnc.com
- 6.4" dia. × 24" capacity
- 3.3" Z (up and down) travel
- Longsworth self-centering chuck
- Proprietary operating system
- Comes as a kit
- Includes a Makita trim router
Over the past few weeks, I’ve been having a lot of fun setting up and exploring a CNC lathe. I’d been toying with the idea of adding a 4th axis to my flatbed CNC router when I came upon the Revolution from BobsCNC. Even in the CNC world, the Revolution is a unique critter. Instead of being an add-on accessory, this machine is a dedicated computer-controlled lathe. And instead of coming as a plug-and-play, steel and aluminum tool, the Revolution arrives in kit form, primarily made of plywood. After giving the matter some consideration, I decided I was up to the challenge the kit offered.
All of BobsCNC kits are similarly designed with laser-cut plywood pieces bolting and slotting together, much like an Erector set combined with Lincoln Logs. While you’d think that 1/4" plywood wouldn’t be stiff enough for such use, the clever engineering behind the way the parts fit together yields a remarkably rigid assembly. By building their machines this way, Bobs can offer more capacity at a lower price than their competitors.
The rub is that you do have to put the kit together. I spent about 12 hours over three days assembling the Revolution. It wasn’t a difficult build, but there are just a lot of parts to assemble and bolts to tighten—among other things, the hardware kit included a bag of 300 M4 × 16 machine screws and a matching bag of M4 nuts. These are the primary connectors used throughout, and there were only a few left over at the end. The online assembly manual ran about 150 pages. I opted not to print it out, although that might have made things easier as I had to scroll up and down a lot as I worked. The instructions were mostly clear, though there were a handful of places where some of the hardware was misidentified and at least one place where the bolt count was wrong, which left me puzzled for a few minutes.
By the end of the process, I had my new machine ready to connect to the computer but for a couple of necessary tweaks. The tailstock needed to be trimmed so it could slide readily on the base. The Z-carriage holding the router needed to be adjusted—be sure to take the time to make sure it moves smoothly before attaching it to the gantry. And it took some fussing to get the Longsworth chuck to operate. This is my least favorite part of the machine, and I’m wondering if I can swap it out for a commercial four-jaw scroll chuck.
Physically connecting the Revolution to the computer was as easy as plugging in the included USB cable. But getting the computer to talk to the Revolution was a little more involved. Every CNC machine needs three pieces of software to operate: a design program where you draw the part you want, a G-code generator that converts your drawing into toolpaths that are called G-code, and finally, a G-code sender that actually communicates the G-code to the CNC machine. Some software programs, such as V-Carve, combine design and tool path generation. Fortunately, I already had V-Carve resident on my computer. If you don’t, bobscnc.com has some options. I did, however, need to download the G-code sender specific to the Revolution. You’ll want the Basic Sender (link on Bobs website), not the open-source G-Code sender mentioned in the manual. You’ll also need to add the post-processor made specifically for the Revolution; the two resident in V-Carve for Bobs other machines won’t work right with round work. It helps to have a little knowledge of computers (or a computer geek on standby) to interpret what the computer tells you to do as you install the software. Once I had all the pieces in place, I was ready to fire up the Revolution and make some dust. For that experience, see Routing in the Round at right.
—Tester, Ken Burton
Routing in the Round
Even after more than a decade of playing with CNC machines, I still get excited when a new one responds to the touch of a keyboard. And the gentle whir the Revolution made as its router traversed the gantry for the first time was just thrilling. Now to get to work. The machine is capable of cutting all sorts of three-dimensional shapes, including spirals, relief carvings, regular spindles (and duplicates), and more. I found learning to design pieces to be cut with the Revolution to be challenging, but V-Carve includes some built-in “Gadgets” that make cutting shapes such as flutes and spirals relatively straightforward. I’m going to need some more time, however, before tackling anything more complex than adding a piece of 3-D clipart to my work. More important is how well the machine cut the pieces I did design. The machine itself is sound and performs well. I had some initial trouble with the chuck slipping, but adding a hose clamp (see photo below) took care of that. And, as with every other CNC machine I’ve used, there is a learning curve here, and I made some mistakes (taking too aggressive a cut, for example) and spoiled some pieces as I climbed it. I think the online documentation could be more comprehensive, but Bob’s tech support is very good—I think Bob himself even picked up the phone on one of my calls. The bottom line? This isn’t the best machine for someone new to CNC, but if you’re looking to get into more advanced machining, it has a lot to offer. I know I’m looking forward to exploring what else it is capable of—I’ve only scratched the surface.
Playing the flute. The machine is capable of routing all sorts of shapes around the outside of a cylinder. A good place to start is with flutes: V-Carve even has a Gadget that makes spacing them easy.
POCKET MILL PRO
Create loose-tenon joinery with a hand drill, end mill, and this aluminum and steel jig. Automatically deepens mortise .05" with each pass and can mill a mortise up to 13⁄4" off the edge of a workpiece. Includes custom bit extension and 6mm carbide end mill; other sizes sold separately.
Precisely set common angles on your sliding bevel gauge, including 15°, 221⁄2°, 30°, 36°, 45°, and 90°. Also sets 1:6, 1:7, and 1:8 dovetail angles. Available in black, blue, or clear anodized aluminum finishes with laser engraved angle measurements.
BRIDGE CITY TOOL WORKS
HP-14 SCRAPER PLANE
Tame the toughest grain with a plane that scrapes instead of shears. The iron angle is adjustable from 88-117°. The lock wheel adjusts blade depth by as little as 0.01mm. Features unique CNC-machined “skeletonized” steel body and rear tote, and mushroom-shaped anodized aluminum front tote.
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