Impressive Junkyard CNC Made From Fancy Garbage

We’ll just come out and say it, [reboots] has friends with nice garbage. Sure, some of us have friends who are desperately trying to, “gift,” us a CRT monitor, hope dropping like a rock into their stomach when they realize they can’t escape the recycling fee.  [reboots] has friends who buy other people’s poorly thought out CNC projects and then gift him with the parts.

After dismantling the contraption he found himself with nice US and Japanese made linear motion components. However, he needed a CNC controller to drive it all. So he helped another friend clean out their garage and came away with a FlashCut CNC controller.

Now that he had a controller and the motion components whirring nicely, he really needed a frame to put it all in. We like to imagine that he was at a friend’s  barbeque having a beer. In one corner of the yard was an entire Boeing 747.  A mouldering scanning electron microscope with a tattered and faded blue tarp barely covering its delicate instrumentation sat in another corner. Countless tech treasures were scattered about in various states. It was then that he spotted a rusting gamma ray spectrometer in the corner that just happened to have the perfect, rigid, gantry frame for his CNC machine.

Of course, his friend obliged and gladly gave up the spectrometer. Now it was time to put all together. The gantry was set on a scavenged institutional door. The linear motion frames were bolted in place. Quite a few components had to be made, naturally, of scrap materials.

spindletest2Most people will start by using a handheld router for the spindle. The benefits are obvious: they’re inexpensive, easy to procure, and generally come with mounts. But, there are some definite downsides, one of the most glaring of which is the lack of true speed control.

Even routers that allow you to adjust the speed (a fairly common feature on new models) generally don’t actually regulate that speed. So, you end up with a handful of speed settings which aren’t even predictable under load. Furthermore, they usually rely on high RPMs to do their work. For those reasons, handheld woodworking routers aren’t the best choice for a mill that you intend to cut metal with.

[reboots] noticed this problem while building this machine and came up with an inexpensive way to build a speed-controlled spindle. His design uses a brushless DC motor, controlled through a hobby ESC (electronic speed control), which uses a belt to drive the spindle. The spindle itself is mounted using skateboard bearings, and ends in an E11 collet (suitable for light machining in aluminum).

With the ESC providing control of the brushless motor, he’s able to directly control the spindle speed via software. This means that spindle speeds can be changed with G-code, allowing for optimized feeds and speeds for different operations. The belt-drive increases torque while separating the motor from the spindle, which should keep things cool, and reduce rotating mass on the spindle itself. Now all [reboots] needs to do is add a DIY tool changer!

29 thoughts on “Impressive Junkyard CNC Made From Fancy Garbage

  1. The belt drive configured like shown on photos will actually increase speed and decrease torque. To increase torque he would need to put smaller pulley on DC motor but he would need to either move spindle farther from plate or make some slot for bigger pulley.

  2. “CRT monitor…can’t escape the recycling fee.” This would be ecologically evil so I’m not suggesting that you do it, but I’ve known people to put CRT monitors into big black “contractor” trash bags and put them in their regular trash containers. Surely, though, it’s much better to recycle properly so that your toxic e-waste can be shipped to some third-world country for disassembly (by peasants who have short lifespans anyway) and therefore not pollute the U.S. of A.

  3. Nice junk if you can get it.

    I’ve been trying to think of repurposable junk for decently rigid frame, to make something like an overbuilt 3D printer cum light duty CNC. At the moment I’m thinking about washing machine frames, from old uprights, not the direct drive type.

    You know the general problem with junk builds of anything, getting reasonable advice anywhere, 3/4 of a thread on the subject will be full of dive down on the floor screaming tantrums that you’re not BUYING X godly part… I get it, decent parts work decent, but stfu and keep to the brief. Even DIY 3D printer fora are getting like that now.

          1. I was so disappointed to find that the harbor freight angle grinders were absolutely excellent and perfect for my use case. I had held off so long to buy a good one. Then one day I needed one immediately and bought the thirty dollar one. It’s been wonderful. Like a hacksaw. You put a good blade on a shitty hacksaw you get a good hacksaw. You put a good grinding wheel on a shitty angle grinder. Congrats. Good angle grinder. (for novice purpose)

  4. I’ve picked up a couple of wide plotters, about 1M print width. Unfortunately they are not the same. My aim is to get 3 and gut them to make a delta printer style 3D printer. So far they cost me about $50. There is some good ‘trash’ available but as I live in rual Australia and most of the good stuff in the cities, it does limit this project a bit. Both these treasures were purchased via Ebay and a 2+ hour drive to Melbourne was required to collect them. I’m a bit jealous of those who have ready access to all the good stuff.

    1. Staples will take CRT monitors, but not televisions. Best Buy charges $25 for CRTs.

      (That said, our municipality will take CRTs for free; you just have to schedule a pickup.)

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