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.

Continue reading “Rolling Around A 4th Axis” →

Building Set Limitations Make For Z-Height Follies

September 1, 2017 by John Baichtal 19 Comments

I’m working on a small CNC mill that uses a robotics building set as a starting point. I don’t know what to expect from the process. Maybe the connections will be too wobbly for the machine to be anything but a curiosity. Maybe I’ll be able to do pen plotting and balsa carving but nothing tougher than that. My goal is to have it carve PCBs, but what ultimately is important is that I have a tool whose awesomeness justifies the expense I’ve put into the project.

So far the process has been fun and interesting. But recently the Z-axis build has been especially so. It raises a really interesting question: where does the balance between unknown finished design and known material parameters fall?

Continue reading “Building Set Limitations Make For Z-Height Follies” →

Custom Cut Resistor Bandoliers

August 28, 2017 by Brian Benchoff 16 Comments

Through-hole resistors come on tape that we’re now calling bandoliers. Since [Spencer] is selling a boatload of his RC2014 backplane computer kits on Tindie, he’s been chopping up a lot of resistor bandoliers. It’s a boring and monotonous job.

Fortunately, a lot of people have had a bandolier cutting problem over the years, and there are some hobbyist-grade robots that will do this work for you. One of the more popular robots tasked for bandolier cutting is a laser cut robot. However, if you already have a laser cutter, why not just use the laser to cut the bandoliers? It’s brilliant in its simplicity.

[Spencer] spent a little bit of time designing a template to turn his laser cutter into a cutter for through hole resistors. No, he’s not trimming the leads — this is just a device to cut resistors into groups mini bandoliers of a handful of resistors. The tool is made out of plywood, with a smaller top piece held down with magnets to keep the resistors aligned.

The entire template is up on Thingiverse, and it’s great if you need to cut hundreds of resistors to kit dozens of projects. If you’re only doing one or two, scissors will be the way to go, but if you’re cursed with the monotony of trimming hundreds there’s no better way to get things done than to put a robot to work.

Swedish Rocket Knives

August 15, 2017 by Brian Benchoff 20 Comments

There are trends in YouTube videos among various video producers. A few weeks ago, it was all about fidget spinners until some niche tech blog ran that meme into the ground. Before that, the theme was red-hot knives cutting through stuff. The setup was simple; just heat a knife up with a blowtorch, cut through a tomato or golf ball, hit stop on the high-speed camera, and collect that sweet, sweet YouTube money.

[David] from RCExplorer.se isn’t like most YouTube stars. He actually knows what he’s doing. When the latest trend of rocket-propelled knives hit the tubes, he knew he could blow this out of the water. He succeeded with a fantastic rocket-propelled machete able to slice through watermelons and fling itself into the woods behind [David]’s house.

Unlike most of the other YouTube stars trying their hand at rocket-powered slicers, [David] is doing this one right. He’s using hobby rocket motors, yes, but they’re reloadable. [David] crafted an engine casing complete with a proper nozzle machined out of stainless for this build. The rocket sled itself is an aluminum bracket bolted to a piece of carbon fiber plate that travels down a rail with the help of four skateboard wheels. A machete is then bolted to the plate, which is propelled down the track a bit faster than 200 km/h.

When it comes to rocket-propelled knives, the word ‘professional’ really doesn’t come into play. This, however, is an amazing piece of craftsmanship that you can check out in the videos below.

Continue reading “Swedish Rocket Knives” →

Turning And Burning With A CNC Pyrography Machine

August 11, 2017 by Dan Maloney 11 Comments

With CNC machines, generally the more axes the better. Three-axis machines with a vertical quill over a rectangular workspace are de rigueur, and adding an axis or two can really step up the flexibility of a machine. But can only two axes be of any use? Sure can, as witnessed by this two-axis CNC wood burning machine.

As [tuckershannon] tells the tale, this was a newbie build aided by the local hackerspace. Axis one is a rotary table of laser-cut wood gears powered by a stepper. Axis two is just a stepper and lead screw sitting on a couple of blocks of wood. A Raspberry Pi under the hood controls the motors and cycles the pyrography pen on and off as it scans across a piece of wood on the rotary table, burning a spiral pattern that makes for some interesting art. Hats off to [tuckershannon] for figuring out the math needed to adapt to the changing speed of the pen over the wood as the diameter gets bigger.

We love this build, can’t help but wonder if some clever gearing could eliminate the need for the second stepper. And perhaps an upgrade from the standard resistive wood burner to an arc lighter pyrography pen would improve resolution. Still, it’s hard to argue with results, and this is a great hack.

[via r/raspberrypi]

Thanks to [Liz] for the tip!

CNC Mill Out Of A Building Set

August 10, 2017 by John Baichtal 19 Comments

I have some aluminum building-set parts on hand and just got a second rotary tool, so I thought I’d try my hand at making a light-duty CNC mill—maybe carve up some cheap pine or make circuit boards. This post explores some of the early decisions I’m facing as I begin the project.

Of primary importance is the basic format of the mill’s chassis. Gantry configuration or put everything in a box of girders? How will the axes move–belts or racks? How will the Z-axis work, the assembly that lowers the tool onto the material? Finally, once the chassis is complete, or perhaps beforehand, I’ll need to figure out how I intend to control the thing.

Continue reading “CNC Mill Out Of A Building Set” →

Fabricate Your Own Tabletop Gaming Props

July 14, 2017 by John Baichtal 13 Comments

Delve into the mysterious world of tabletop roleplaying games. Warhammer Fantasy Roleplay, Shadowrun, Pathfinder, Ars Magica, Vampire, whatever gets your dice rollin’ — metaphorically in the case of a diceless system. This might very well be your daddy’s D&D. If you’re not a gamer, you’re certainly familiar with the concept. People sit around a table pretending to have an epic adventure, often adding a random element with the help of dice. A map is often displayed on the table, sized for figures that show the various heroes and villains.

As a person with access to a variety of CNC machines I find myself wanting to create things to make gameplay more fun. I want to build a scale castle and have a siege. I want to conduct a ship-to-ship battle with wooden ships built to scale. But I also think smaller. What is something I could make that would help us every day? Say, a box for dice. Not every project needs to be the dragon’s lair.

It turns out a lot of other folks have been thinking about the same thing.

Continue reading “Fabricate Your Own Tabletop Gaming Props” →