CNC Robot Makes A Move

October 12, 2017 by DJ Harrigan 30 Comments

Another day, another Kickstarter. While we aren’t often keen on touting products, we are keen on seeing robotics and unusual mechanisms put to use. The Goliath CNC has long since surpassed its $90,000 goal in an effort to put routing robots in workshops everywhere.

Due to their cost and complexity, you often only find omni-wheels on robots scurrying around universities or the benches of robotics hobbyists, but the Goliath makes use of nine wheels configured as three sets in a triangular pattern. This is important as any CNC needs to make compound paths, and for wheeled robots an omni-wheel base is often the best bet for compound 2D translation.

What really caught our eye is the Goliath’s unique positioning system. While most CNC machines have the luxury of end-stops or servomotors capable of precise positional control, the Goliath has two “base sensors” that are tethered to the top of the machine and mounted to the edge of the workpiece. Each sensor connects to the host computer via USB and uses vaguely termed “Radio Frequency technology” that provides a 100Hz update for the machine’s coordinate system. This setup is sure to beat out dead-reckoning for positional awareness, but details are scant on how it precisely operates. We’d love to know more if you’ve used a similar setup for local positioning as this is still a daunting task for indoor robots.

A re-skinned DeWalt 611 router makes for the core of the robot, which is a common option for many a desktop milling machine and other bizarre, mobile CNCs like the Shaper Origin. While we’re certain that traditional computer controlled routers and proper machining centers are here to stay, we certainly wouldn’t mind if the future of digital manufacturing had a few more compact options like these.

Engineering And Artistry Meet An Untimely End At Burning Man

October 6, 2017 by Dan Maloney 38 Comments

Burning Man is so many different things to so many people, that it defies neat description. For those who attend, it always seems to be a life-changing experience, for good or for ill. The story of one man’s Burning Man exhibition is a lesson in true craftsmanship and mind-boggling engineering, as well as how some events can bring out the worst in people.

For [Malcolm Tibbets], aka [the tahoeturner], Burning Man 2017 was a new experience. Having visited last year’s desert saturnalia to see his son [Andy]’s exhibition, the studio artist decided to undertake a massive display in his medium of choice — segmented woodturning. Not content to display a bamboo Death Star, [Malcolm] went big– really big. He cut and glued 31,000 pieces of redwood into rings of various shapes and sizes and built sculptures of amazing complexity, including endless tubes that knot and loop around and back into each other. Many of the sculpture were suspended from a huge steel tripod fabricated by [Andy], forming an interactive mobile and kinetic sculpture.

Alas, Burning Man isn’t all mellowness in the desert. People tried to climb the tripod, and overnight someone destroyed some of the bigger elements of the installation. [Malcolm] made a follow-up video about the vandalism, but you’ll want to watch the build video below first to truly appreciate the scale of the piece and the loss. Here’s hoping that [Malcolm]’s next display is treated with a little more respect, like this interactive oasis from BM 2016 apparently was.

Thanks to [Keith Olson] for the tip.

Adding Screws To A DIY CNC Machine

October 4, 2017 by Brian Benchoff 24 Comments

When it comes to CNC machines, your SureFine has screws on its axes, and the Bodgeport does too. A shopbot has an amazing rack gear system, but when you start to dig into the small CNC routers available for under $2,000, you’ll only find belts moving a router back and forth. This isn’t to say belts won’t work — you can create a fine CNC machine with bits of rubber. However, belts stretch, they wear out, and if you want more precision screws and racks are the way to go.

The WorkBee CNC machine is the first desktop CNC router we’ve seen that uses screws instead of belts. It’s a project on OpenBuilds, and a reasonably well-configured machine is now available from ooznest for about £1,700 ($2,200 USD), or just a bit more than other CNC routers that consist of a Dewalt router and some aluminum extrusion.

The WorkBee CNC is based on the OX CNC machine, another cartesian router machine built around the OpenBuilds aluminum extrusion. The OX, while a fine machine for DIY tinkerers, uses belts. The WorkBee trades them out for screws, and should gain better accuracy, much lower maintenance, and deeper cuts. Screws are slower, yes, but do you really need that much acceleration when routing a thick piece of wood?

Hackaday Prize Entry: TooWheels, The Open Source Wheelchair

September 27, 2017 by Anool Mahidharia 17 Comments

The Assistive Technology challenge of the Hackaday Prize received a large number of projects addressing many socially relevant problems. Mobility and transportation needs are a big challenge for those with limb disabilities. Not every country has proper, state-subsidised health care systems, and for many people in third world countries, devices such as wheel chairs are just not affordable. [Alessio Fabrizio] and his team developed TooWheels — an Open Source DIY wheelchair which can be customized and built using low-cost, local materials around the world and is one of the winners of the Assistive Technologies challenge round.

Originally conceived as a sport wheelchair, it has now evolved to answer different needs, due to feedback from the users and the community involved in the project. [Alessio] designed the project to be built from materials and resources easily available to any DIY maker at today’s Fab Labs and Makerspaces. The team have provided a detailed BOM to help procure all the required materials, instruction manual and drawings for assembly, and all the CAD files with customization instructions. Already, teams in Ecuador, India and Italy have replicated and built their own version of the TooWheel wheelchair. This confirms that the project is well documented and allows anyone around the world to download the plans and follow instructions to build their own wheelchair.

The wheelchair is built from CNC cut plywood sheets, aluminum pipes and bicycle parts and wheels. This makes it substantially cheaper compared to commercial wheelchairs, making it especially relevant for people in third world areas or where health care is not subsidised. The ease of customization allows fabrication of different wheelchair designs for sports, off-road or city use. The team is looking to bring this low-cost design to people around the world and are keen to collaborate with teams around the world to make it happen.

BeamCNC: Computer-Controlled Construction System Mill

September 27, 2017 by John Baichtal 8 Comments

Need to make something quick and dirty out of wooden beams, and want to use elements you know will work together? BeamCNC is a mobile assembly of stepper-controlled rollers and a router that sucks a 2×2 through it and drills the holes in pre-programmed intervals. Currently being developed as part of an Indiegogo campaign currently in preview, its creator [Vladislav Lunachev] has declared it open source hardware. It’s essentially a CNC mill that makes Grid Beam, a classic DIY building set that resembles Meccano, Erector, and other classic sets, only made full-scale for larger projects. While BeamCNC is not affiliated with Grid Beam, it takes the same general idea and automates it.

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Better Stepping With 8-Bit Micros

September 17, 2017 by Brian Benchoff 43 Comments

The electronics for motion control systems, routers, and 3D printers are split into two camps. The first is 8-bit microcontrollers, usually AVRs, and are regarded as being slower and incapable of cool acceleration features. The second camp consists of 32-bit microcontrollers, and these are able to drive a lot of steppers very quickly and very smoothly. While 32-bit micros are obviously the future, there are a few very clever people squeezing the last drops out of 8-bit platforms. That’s what the Buildbotics team did with their ATxmega chip — they’re using a clever application of DMA as counters to drive steppers.

The usual way of driving steppers quickly with an ATMega or other 8-bit microcontroller is abusing the hardware timers. It’s quick, but there is a downside. It takes time for these timers to start and stop, and if you’re doing it two hundred times per second with four stepper motors, that clock jitter will ruin your CNC machine. The solution is to use a DMA channel to count down, with each count sending out a pulse to a stepper. It’s a clever abuse of the hardware, and the only drawback is the micro can’t send more than 2¹⁶ pulses per any 5ms period. That’s not really an issue because that would mean some very, very fast acceleration.

The Buildbotics team currently has a Kickstarter running for their four-axis CNC controller using this technique. It’s designed for Taig mills, 6040 routers, K40 lasers, and other various homebrew robots. It’s an interesting solution to the apparent end of the of the age of 8-bit microcontrollers in CNC machines and certainly worth checking out.

Rolling Around A 4th Axis

September 3, 2017 by Brian Benchoff 23 Comments

[Perry] was interested in adding a 4th axis to his CNC machine, but not very excited at the prospect of spending hundreds of dollars on the parts and electronics to make it work. There is a very clever and very inexpensive way to add a 4th axis to a CNC machine, though, and after a bit of fabrication, he was able to add a ‘rolling’ 4th axis to his machine.

The idea for this build comes from [Bob] over on the CNC Shark forums. Instead of adding a motor to rotate a work piece around, [Bob]’s build simply mounts it between two jaws, and rolls everything around against the bed of the CNC router. Don’t have a clue what that means? Check out the picture to the right, and you’ll see brilliance built in Delrin and HDPE. By mounting two rack gears to the bed and two geared jaws to the carriage of the machine, moving the router in the Y axis also rotates the 4th axis. This is far, far too clever; it doesn’t require any additional electronics and the only software tweaks are a bit of G-code hacking.

[Perry] took one look at [Bob]’s project and decided this would be the perfect build to get him a 4th axis. The parts for this build were fabricated out of black HDPE, with the only real change to the design being a ‘variable length’ 4th axis. Instead of two rack gears mounted to the bed of the machine, [Perry]’s build only uses one rack, with the other end simply rolling on the bed.

There are a lot of clever inventions that don’t work, so what’s the verdict with this CNC hack? It actually looks pretty good. [Perry] was able to turn some square stock into round stock, and able to engrave a spiral around a cylinder. You can check out those videos below.

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