Printrbot just released the Crawlbot, a game changer in the world of CNC. It takes one basic fundamental of CNC machines and throws it out the window: The idea that if you want to cut a large piece of material, then your machine needs to have an even larger frame. Instead, the Crawlbot is the size of a golf bag but can cut material larger than a sheet of plywood.
This is the perfect machine for the at-home tinkerer, someone who doesn’t have a lot of work space but can back the car out of the garage on the weekends. If you want to cut full sheets of plywood, you no longer need to put an unmovable, VW-sized machine in your shop, taking up a substantial amount of room. Instead, you store the Crawlbot in a tight space, then when needed you simply strap it to a single piece of plywood on a few sawhorses and let it run. And it costs $4000 (currently set at an introductory $3500), where traditional machines with comparable capabilities start in the tens of thousands of dollars.
We tested a prototype of Crawlbot this summer for the upcoming Make: magazine desktop fabrication issue; this is the review that will be included in that issue (on newsstands this November).
Ingenious Engineering
Crawlbot’s engineering is ingeniously simple. Instead of relying on the machine’s oversized skeletal structure, this parasitic bot gains structure by simply attaching to the very material it’s cutting. The X- and Z-axis are fairly conventional, running along sturdy extruded aluminum. The real magic, however, is in the Y-axis. There are two drive belts that run the length of the wood and clamp securely to all four corners. Riding along what amounts to rollerblade wheels, and using the straight edge of the plywood as a guide, the Crawlbot lives up to the name by pulling itself along the stationary drive belts to traverse the length of the material.
I was excited to see it in action, and curious if it would maintain its place as well as conventional CNCs do. It worked perfectly, cutting out an AtFab chair with spot-on joinery.
Smooth and Solid
Although we only had a prototype model, I was very impressed with the hardware. Solid construction with extruded aluminum and a manually controlled Makita router attachment (glad to see that they didn’t “cheap out” on brand, although it would be nice to have automated RPM). The cutter head travel is elegantly smooth, running off of a TinyG housed in a sturdy box.
The machine weighs 65 lbs, not unmanageable alone but it’s nice to have a buddy to help for the first few runs. After that the flow becomes a little easier alone.
Unfortunately the machine’s greatest strength also becomes its weakness. The Crawlbot rides along the very surface it’s cutting, which means it still needs a place to stand as it works. This causes the bot to leave an almost 4 inch border, on all sides, of unusable material. So all those wonderful designs that fit into the standard 4×8 aren’t compatible. I found a few workarounds for this — such as using a larger second board as the table to hold the belts and the material. PrintrBot is releasing plans at launch, for a table that can be cut on the Crawlbot and will fix this problem for anyone who sees it as an issue.
Minor Downsides
The Crawlbot is not a complete replacement for the conventional CNC router. It’s restricted to working on a fairly flat, straight-sided material. The Z-height is a bit lacking, just a little over 2 inches. Also keep in mind that the machine will set up quickly but figuring out a system for power cords, vacuum hoses, and data connection makes it a little less versatile than at first glance.
But because of price and portability I think this humble little machine could pull a good portion of the full-sized CNC’s sales. At $3999, it costs a fifth of what many full-sized CNC’s go for. Printrbot has a great idea here. In fact it’s so great (depending on what patents they have been able to secure) I think we will soon see other companies developing similar products.
Pro Tips
Want to get the most efficient cut out of your grade-A wood? You can cut right up to the edge of your material by screwing down to a larger waste board. It reduces the Z-height a bit, but can help prevent a reduction in your wallet height by not having to throw away good material.
Why to Buy
Tight on space? Tight on budget? Like to tinker? This is the machine for you. It has a solid performance at a fraction of the cost of larger units and, like any useful woodworking tool, it’s ripe with opportunity for customization.
Manufacturer: Printrbot
Price as Tested: $3999
Build Volume: Adjustable up to 5’x10’
Host Software: Custom Printrbot CNC control software
CAM: Fusion 360 or custom Printrbot software
Firmware: TinyG
OS: Cross platform Chrome extension
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