Build Your Own CNC With the SainSmart Genmitsu CNC Router PRO DIY Kit

First things first: what does CNC actually stand for? It’s “computer numerical control,” and while it’s usually the way many people refer to one specific device, the CNC router, it actually covers the whole class of computer-controlled tools, like lathes, drills, laser cutters, and even 3D printers. But this post is about CNC routers, and specifically my journey assembling and starting to use the SainSmart Genmitsu 3018 PRO (provided to me by SainSmart for this purpose). A router is a rotary device (like a Dremel) used for cutting materials like wood into useful and decorative shapes. There are some folks who believe that CNC routers are far more useful tools than their trendy counterparts, the 3D printer. That’s up to you do decide.

I’ll also mention up front that this is an experience for a hobbiest and a tinkerer. The device comes unassembled, and you have to put it together using instructions that are only slightly better than what comes with an Ikea bookcase. If you do great with Ikea building jobs, you’ll do great here. If you want more hand-holding, or a ready-to-use tool, consider spending the money for a fully-assembled device.

With that warning in place, I have to admit that assembling the Genmitsu 3018 PRO was actually pretty straightforward, and I felt like I understood the instructions and knew what I was doing the whole way through. You build the base and vertical supports out of strong aluminum and vinyl girders, using easy hex-head screws for everything (the Allen wrenches are included, just like Ikea, as well!). Motors mount to the back, side, and on the z-axis frame, and the controller board (Ardiuno) screws to the back of the frame. Wire everything up, plug it in, and connect to your computer via USB, and you’re ready to go. For me, getting from unassembled parts in a box to a ready-to-route CNC device took about two hours in total.

Once I got the CNC router attached to my computer, it was time for some education. I’ve messed about with 3D printers in the past, so I understood the general concepts, but I needed to familiarize myself with the specific open-source software (GRBL) running the router. This is where my inexperience tripped me up.

Using GRBL, you can run files that will instruct the router to carve whatever you have on the work plate, or you can manually move it around by clicking on the controls on the screen. I had done this a few time, just testing the router out, but at some point, I started clicking the controls to make it move the router left or right or up or down, and while the motors seemed to be running, nothing appeared to be happening. I got frustrated and left it for a while to try and figure out if I had assembled it wrong, or blown something out and would need to get a replacement.

A few days later, I went back to try again. I thought perhaps I hadn’t tightening down the couplings between the motors and the drive rods tightly enough, and something was slipping. I checked them, and they all seemed good, though. I went back to GRBL and started pushing arrows again, and it was the same. Things sounded like they were working, but the router wasn’t moving. Or was it? I looked closer, and realized the motors were indeed moving and turning the drive rods, just in very very tiny increments. Turns out I’d tweaked a setting in GRBL that meant the controls were making moves that were so minute, I couldn’t see them. I upped the numbers, and suddenly everything started working again!

So, now I could start my first project. The kit comes with a couple samples you can just load and play with, but I wanted to do something special for this review. That’s where more education came into play though. My experience in the past had been with 3D printers, where you design some kind of 3-dimensional object and the printer spits it out in plastic. With a CNC router, what you actually do is design a digital 3D version of the block of wood or other material that’s the base of your project, then you design what you’re removing from that base, and then you run a program that translates that design into the actions that your router will need to take to realize it. This program takes into account the shape of the bit in the router, the speed the router can run at, and a slew of other considerations. You run the program, and it spits out a file you’ll open in GRBL.

With the file open in GRBL, you clamp your blank down to the work surface, and you’re ready to go! Well, not quite. One more key thing to do is align the starting point of the tip of your router bit. See, when you created the design and run file, you included information for where the router bit would be positioned at the start of the process; effectively you told it your router bit would be a specific location in relation to the design in virtual X-Y-C coordinate space. So, when you’re ready to run the program, you have to align the actual router bit to that position, so that every instruction that follows traces the same path in real-space that the software designed for it virtually.

I’ll be honest that this took me some trial-and-error to get right. This is where some inexperience, combined with the fact that these are such flexible tools that, because you can do so much with them, it’s really easy to make mistakes even with the simple stuff. One time, I got the alignment wrong so that the bit drilled too deeply, and the result looked poorly. A couple times, I didn’t get the block fastened down to the workbed well enough, and it shifted. In the end, it took me about six tries before I got a result I’d call a solid result. But, I’m pretty proud of what I did, because before I started this process, I’d never worked with a CNC router.

Not bad, I think! It will take a bit of sanding, and staining to finish it, but I’m happy with the result (available soon on the GeekDad store /not/). I’ll also mention that my starting point there were blank wood coasters I picked up at Michaels for a couple dollars a piece. They made for a perfect starting project.

In the end, I’m excited with the possibilities. This is very much an entry-level device, but it’s perfect for starting out on the CNC journey, and the extra education involved in building it myself (with the mistakes made) only added to the journey. I already have plans for holiday ornaments I can make for family and friends. On top of that, Genmistu sent me the laser unit that you can swap in for the router, which opens up whole other avenues of projects to try.

With the holidays coming up, I think the SainSmart Genmitsu CNC Router PRO DIY Kit would make a great gift for the tinkering, budding woodworking geek in your life. Right now, it lists for $240, but you can get an additional 20% off your first purchase when you sign up for their mailing list, so it makes for a really good value. Plus, they’ve set up a coupon code for another $25 off: Use code GEEKDAD for $25 off all 3018 CNC machines. Check it out here!

And here’s a quick stop-motion video of the router on one of its runs:

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