Testing An Inexpensive CNC Spindle

The old saying “you get what you pay for” is a cautionary cliché, but is directly contrary to several other common sayings. In the case of [Spikee]’s planned CNC machine build, he took the more adventurous idiom of “no risk, no reward” to heart when he purchased these spindles for the machine from AliExpress. While the delivered product seemed fine, there were some problems that needed investigations.

Upon delivery of the spindle, everything seemed to work correctly out-of-the-box. Even the variable frequency drive, which was programmed at the factory, was working properly. But at around 8000 rpm the machine would begin shaking. The suspected part causing the vibration was the tool holder, so after checking the machine’s runout and also using a specialized vibration sensor this was confirmed to be the case.

Luckily [Spikee] was able to get a refund on the tool holders since they were out of spec, but still has a quite capable spindle on his hands for an excellent price. Without some skills in troubleshooting he might have returned the entire machine unnecessarily. If you are looking for some other ideas in setting up an inexpensive CNC machine, you might also like to look at BLDC motors from a remote control vehicle.

Electronic leadscrew

Electronic Lead Screws – Not Just For Threading Anymore

An electronic leadscrew is an increasingly popular project for small and mid-sized lathes. They do away with the need to swap gears in and out to achieve the proper ratio between spindle speed and tool carriage translation, and that makes threading a snap. But well-designed electronic leadscrews, like this one from [Hobby Machinist], offer so much more than just easy threading.

The first thing that struck us about this build was the polished, professional look of it. The enclosure for the Nucleo-64 dev board sports a nice TFT display and an IP65-rated keyboard, as well as a beefy-looking jog wheel. The spindle speed is monitored by a 600 pulses-per-revolution optical encoder, and the lathe’s leadscrew is powered by a closed-loop NEMA 24 stepper. This combination allows for the basic threading operations, but the addition of a powered cross slide opens up a ton more functionality. Internal and external tapers are a few keypresses away, as are boring and turning and radius operations, both on the right and on the left. The video below shows radius-cutting operations combined to turn a sphere.

From [Hobby Machinist]’s to-do list, it looks like filleting and grooving will be added someday, as will a G-code parser and controller to make this into a bolt-on CNC controller. Inspiration for the build is said to have come in part from [Clough42]’s electronic leadscrew project from a few years back. Continue reading “Electronic Lead Screws – Not Just For Threading Anymore”

Vertical Mill Completes Scrapyard Lathe Build

One thing’s for sure: after seeing [Roland Van Roy] build a vertical mill from industrial scrap, we’ve got to find a better quality industrial scrapyard to hang around.

The story of this build started, as many good shop stories do, at the lathe, which in this case was also a scrapyard build that we somehow managed to miss when it first posted. This lathe is decidedly different from the common “Gingery method” we’ve seen a few times, which relies on aluminum castings. Instead, [Roland] built his machine from plate stock, linear slides, and various cast-off bits of industrial machines.

To make his lathe yet more useful, [Roland] undertook this build, which consists of a gantry mounted over the bed of the lathe. The carriage translates left and right along the bed while the spindle, whose axis lines up perfectly with the center axis of the lathe, moves up and down. [Roland] added a platform and a clever vise to the lathe carriage; the lathe tool post and the tailstock are removed to make room for these mods, but can be added back quickly when needed. Digital calipers stand in for digital read-outs (DROs), with custom software running on a Picaxe and a homebrew controller taking care of spindle speed control.

[Roland] reports that the machine, weighing in at about 100 kg, exhibits a fair amount of vibration, which limits him to lighter cuts and softer materials. But it’s still an impressive build, and what really grabbed us was the wealth of tips and tricks we picked up. [Roland] used a ton of interesting methods to make sure everything stayed neat and square, such as the special jig he built for drilling holes in the T-slot extrusions to the use of cyanoacrylate glue for temporary fixturing.

Continue reading “Vertical Mill Completes Scrapyard Lathe Build”

Mini CNC Mill Goes Horizontal To Reuse CD Drives

Here at Hackaday, we pride ourselves on bringing you the freshest of hacks, preferably as soon as we find out about them. Thanks to the sheer volume of cool hacks out there, though, we do miss one occasionally, like this e-waste horizontal CNC mill that we just found out about.

Aptly called the “CDCNC” thanks to its reliance on cast-off CD drive mechanisms for its running gear, [Paul McClay]’s creation is a great case study on what you can do without buying almost any new parts. It’s also an object lesson in not getting caught in standard design paradigms. Where most CNC mills mount the spindle vertically, [Paul] tilted the whole thing 90 degrees so the spindle lies on its side. Moving it back and forth on a pair of CD drive mechanisms is far easier than fighting gravity for control, and as a bonus the X- and Y-axes have minimal loading too. The video below shows the mill in action, and it’s easy to see how the horizontal arrangement really helps make this junk bin build into something special.

We think [Paul] did a great job of thinking around the problem with this build, and we’re glad he took the time to tip us off. Apparently it was the upcoming CNC on the Desktop Hack Chat that moved him to let us know about this build. Here’s hoping he drops by for the chat and shares his experience with us.

Continue reading “Mini CNC Mill Goes Horizontal To Reuse CD Drives”

Analyzing CNC Tool Chatter With Audacity

When you’re operating a machine that’s powerful enough to tear a solid metal block to shards, it pays to be attentive to details. The angular momentum of the spindle of a modern CNC machine can be trouble if it gets unleashed the wrong way, which is why generations of machinists have developed an ear for the telltale sign of impending doom: chatter.

To help develop that ear, [Zachary Tong] did a spectral analysis of the sounds of his new CNC machine during its “first chip” outing. The benchtop machine is no slouch – an Avid Pro 2436 with a 3 hp S30C tool-changing spindle. But like any benchtop machine, it lacks the sheer mass needed to reduce vibration, and tool chatter can be a problem.

The analysis begins at about the 5:13 mark in the video below, where [Zach] fed the soundtrack of his video into Audacity. Switching from waveform to spectrogram mode, he was able to identify a strong signal at about 5,000 Hz, corresponding to the spindle coming up to speed. The white noise of the mist cooling system was clearly visible too, as were harmonic vibrations up and down the spectrum. Most interesting, though, was the slight dip in frequency during the cut, indicating loading on the spindle. [Zach] then analyzed the data from the cut in the frequency domain and found the expected spindle harmonics, as well the harmonics from the three flutes on the tool. Mixed in among these were spikes indicating chatter – nothing major, but still enough to measure.

Audacity has turned out to be an incredibly useful tool with a broad range of applications. Whether it be finding bats, dumping ROMs, detecting lightning strikes, or cloning remote controls, Audacity is often the hacker’s tool of choice.

Continue reading “Analyzing CNC Tool Chatter With Audacity”

Unique 3D Printer Turned CNC Engraver

As we’ve said in the past, one of the most exciting things about the proliferation of low-cost desktop 3D printers (beyond all the little boats we get to see on Reddit), is the fact that their motion control systems are ripe for repurposing. Outfitting a cheap 3D printer with a drag knife, pen holder, or even a solid-state laser module, are all very common ways of squeezing even more functionality out of these machines.

But thanks to the somewhat unusual nature of his printer, [Hammad Nasir] was able to take this concept a bit farther. Being considerably more rigid than the $99 acrylic-framed box of bolts we’ve become accustomed to, he was able to fit it with a basic spindle and use it for CNC engraving. He won’t be milling any steel on this rig, but judging by the pictures on the Hackaday.io page for the project, it does a respectable job cutting designs into plastic at least.

The IdeaWerk 3D printer that [Hammad] used for this project is phenomenally overbuilt. We don’t know whether the designers simply wanted to make it look futuristic and high-tech (admittedly, it does look like it could double as a movie prop) or they thought there was a chance it might get thrown down the stairs occasionally. In either event, it’s built like an absolute tank.

While the frame on lesser printers would likely flex as soon as the bit started moving across the workpiece, this thing isn’t going anywhere. Of course this machine is presumably still running on the standard GT2 belt and NEMA 17 arrangement that has been used in desktop 3D printers since the first wooden machines clattered to life. So while the frame might be ready to take some punishment, the drive system could respectfully disagree once the pressure is on.

Modification was simplified by the fact that the hotend and extruder assembly on the IdeaWerk is mounted to the X axis with just a single bolt. This makes it exceptionally easy to design alternate tool mounts, though arguably the 3D printed motor holder [Hammad] is using here is the weak link in the entire system; if it’s going to flex anywhere, it’s going to be there.

If you’re more photonically inclined, you might be interested in this similarly straightforward project that sees a 2.5 W laser module get bolted onto an entry level 3D printer.

Steel Tubes And Ground Plates Form The Skeleton Of This DIY Vertical CNC Mill

If you’re going to do it yourself, you might as well outdo yourself. That seems to be the thinking behind this scratch-built CNC mill, and it’s only just getting started.

According to [Kris Temmerman], the build will cost about $10,000 by the time he’s done. So it’s not cheap, and a personal CNC from Tormach can be had for less, but that’s missing the point entirely. [Kris] built most of the structural elements for the vertical mill from cheap, readily available steel tubing, of the kind used for support columns in commercial buildings. Mounted to those are thick, precision-ground steel plates, which eat up a fair fraction of the budget. Those in turn hold 35 mm linear bearings and ball screws for the three axes, each powered by a beefy servo. The spindle is a BT30 with a power drawbar, belt-driven by an external motor that [Kris] doesn’t share the specs on, but judging from the way it flings chips during the test cut in the video below, we’d say it’s pretty powerful.

There’s still plenty to do, not least of which is stiffening the column; perhaps filling it with epoxy granite would do the trick? But it sure looks like [Kris] is building a winner here, and if he keeps the level of craftsmanship up going forward, he’ll have a top-quality machine on his hands.

Continue reading “Steel Tubes And Ground Plates Form The Skeleton Of This DIY Vertical CNC Mill”