Design Tips For Easier CNC Milling

CNC machining is a wonderful thing, taking away a lot of the manual work required in machining and replacing it with accurate, repeatable computer control. However, this doesn’t mean that you can simply click a few buttons and become a great machinist overnight. There are a wide variety of skills involved in utilizing these tools effectively, and [Adam Bender] has created a guide to help budding makers learn the skills of design for CNC milling. 

[Adam]’s guide starts from a basic level, considering 3-axis CNC milling with the most commonly used tools. From there, a whole range of tips, tricks, and potential pitfalls are discussed to help new machinists get to grips with CNC milling. Everything from dogbone corners, to tool selection and feature heights are covered, as well as cost-saving techniques like minimising the number of setups required.

These are skills any engineer will learn in a hurry when approaching an experienced CNC machinist, but it’s always better to go in forewarned and forearmed. Of course, for those eager to not just work with, but build their own CNC machine, we’ve covered that base too. Video after the break.

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How Much Wood Can a Woodpecker Chuck?

It’s probably clear to a Hackaday reader that we live in a golden era for hobbyist tool accessibility. Cheap single board computers can be bought at any neighborhood RadioShack or Maplin. 3D printers sell fully assembled and ready to run for less than $200. Even the humble CNC mill has come down the price curve, though as you might expect at the low end things can get pretty rough. Like a cheap 3D printer, a cheap mill tends to be missing some basic features you’d expect any reasonable machine to have. If you get your hands on one of these little wonders, [Shahada Abubakar] has a pair of great blog posts on the basic set of upgrades you’ll probably want to perform right out of the box.

Which cheap CNC mills are we talking about? They go by a few names. Last year our own [Kristina Panos] put together a review of a shockingly inexpensive “1610” type sold by Linksprite (go take a read if you’re already considering a purchase!). The “1610” class, so named for it’s 16 cm x 10 cm bed size, is pretty common under a wide variety of manufacturer names. You can find them in this size made of 8020 like [Kristina] did or as “upgraded” versions cut from 1/4″ mystery plastic (often referred to in the listings as Bakelite, but your guess is as good as ours as to the true material). 1610 is the smallest size but basically the same machine exists as an 1810, 2418, or 3018. Each has a 775 size spindle and a single PCBA that handles stepper drive and runs grbl.

So what’s the problem? Well for one none of these machines have limit switches, though the controllers support them. [Shahada]’s guide has handy instructions for what kind to buy, how to wire them, and where they can be attached. Plus an overview of the G-code instructions to send the controller in order to home and configure everything properly. The controllers also like to be driven continuously over serial (though some sellers seem to offer a separate board to drive them). This is fine if you have a computer handy, but like a 3D printer it can be nice to bolt a Pi Zero or similar onto the unit and control it over the network. [Shahada]’s second post has a link to a mounting plate you can print for exactly that setup, as well as some suggestions for configuring CNC.js to drive everything.

Do you have one of these machines? Done any upgrades? Tell us in the comments! We’re always looking for ways to upgrade our home shop.

How To Build A Mill With Epoxy

The typical machine tool you’ll find in a workshop has a base and frame made of cast iron or steel. These materials are chosen for their strength, robustness and their weight, which helps damp vibrations. However, it’s not the only way to make a machine tool. [John McNamara] has been working on a CNC mill with an epoxy base, with impressive results.

The molds were designed in CAD prior to casting, ensuring there was room for all required components.

The build is one that could be readily achieved in any decently equipped makerspace. [John] used lasercut steel parts to construct the molds for the epoxy base, with some custom turned parts as well. The precision cut parts fit together with great accuracy, and with proper control of the casting process there is minimal post-processing of the final cast piece required. The mold is built with zero draft angle, and is designed to be taken apart to remove the finished pieces. By using steel, the same mold can be used many times, though [John] notes that MDF could be used for a one-off build.

The base is cast in epoxy, mixed with granite aggregate and sand to create a strong, heavy, and vibration damping material. There are also steel reinforcements cast in place consisting of threaded rods, and conduits for various electrical connections. After casting, [John] has spent much time measuring and truing up the mill to ensure the best possible results from the outset.

It’s an impressive build, that shows that building your own accurate machine tools is quite achievable with the right tools and knowledge. We’ve seen similar work before, too – epoxy really does make a great material for casting at home.

 

A 3D Printer To PCB Miller Conversion

Got a 3D printer? With a bit of work, you may also have a PCB miller. That’s the basis of this neat hack by [Gosse Adema], who converted an Anet A8 3D printer into a PCB miller by building a holder for a Dremel rotary tool and adapting the GCode. This approach means that the adaptations to the printer are minimal: the only hardware is a 3D-printed holder for the Dremel that replaces the print head. The result is an impressive PCB milling machine that can do double-sided PCBs and make through holes.

The excellent write-up that [Gosse] did on this hack describes how he converted the printer, and how he took an EagleCAD design and converted it into four GCode files. That’s one for each side of the PCB, one for through holes and one for the final outline of the PCB. These are then fed to the 3D printer and cut in turn with an appropriate milling bit on the Dremel.

We’ve featured a few similar conversions before, such as this vintage conversion of a Makerbot and this cheap engraver conversion, but this one is much more detailed than those, covering the entire process from PCB design to final product.

Soundproofing A CNC Mill Conversion

The Proxxon MF70 is a nice desktop sized milling machine with a lot of useful add-on accessories available for it, making it very desirable for a hacker to have one in his or her home workshop. But its 20000 rpm spindle can cause quite the racket and invite red-faced neighbors. Also, how do you use a milling machine in your home-workshop without covering the whole area in metal chips and sawdust? To solve these issues, [Tim Lebacq] is working on Soundproofing his CNC mill conversion.

To meet his soundproof goal, he obviously had to first convert the manual MF70 to a CNC version. This is fairly straightforward and has been done on this, and similar machines, in many different ways over the years. [Tim] stuck with using the tried-and-tested controller solution consisting of a Raspberry Pi, an Arduino Uno and a grbl shield sandwich, with stepper motor drivers for the three NEMA17 motors. The electronics are housed inside the reclaimed metal box of an old power supply. Since the Proxxon MF70 is already designed to accept a CNC conversion package, mounting the motors and limit switches is pretty straightforward making it easy for [Tim] to make the upgrade.

Soundproofing the box is where he faced unknown territory. The box itself is made from wooden frames lined with particle board. A pair of drawer slides with bolt-action locks is used for the front door which opens vertically up. He’s also thrown in some RGB strips controlled via the Raspberry-Pi for ambient lighting and status indications. But making it soundproof had him experimenting with various materials and techniques. Eventually, he settled on a lining of foam sheets topped up with a layer of — “bubble wrap” ! It seems the uneven surface of the bubble wrap is quite effective in reducing sound – at least to his ears. Time, and neighbours, will tell.

Maybe high density “acoustic foam” sheets would be more effective (the ones similar to “egg crate” style foam sheets, only more dense)? Cleaning the inside of the box could be a big challenge when using such acoustic foam, though. What would be your choice of material for building such a sound proof box? Let us know in the comments below. Going back many years, we’ve posted about this “Portable CNC Mill” and a “Mill to CNC Conversion” for the Proxxon MF70. Seems like a popular machine among hackers.

Home Made 5-Axis CNC Head Is A Project To Watch

[Reiner Schmidt] was tired of renting an expensive 5-axis CNC head for projects, so he decided to build his own. It’s still a work in progress, but he’s made remarkable progress so far. The project is called Bridge Boy, and it is designed to use a cheap DC rotary mill to cut soft materials like plastic, wood and the like. Most of it is 3D printed, and he has released the Autodesk 360 plans that would allow you to start building your own. His initial version uses an Arduino with stepper drivers, and is designed to fit onto the end of a 60mm arm of a standard 3-axis CNC,  so technically it’s a 3+2 axis CNC. With the appropriate software, it should be able to work as a full 5-axis machine, though, and it should be possible to integrate it with a CNC that has a 5-axis driver board without too much effort.

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Hackaday Prize Entry: CNC Mill Lets Kids Engrave on the Fly

The manufacturing revolution has already begun, and there are 3D printers, CNC machines, and laser cutters popping up in garages and workspaces all around the world. The trouble with these machines is that they’re fiddly to use, and you don’t want a kid playing around with them.

[moritz.messerschmidt]’s Hackaday Prize entry is a desktop Badgemaker that engraves acrylic name badges for kids. Under the hood, an Arduino with a custom-built shield with 3 SilentStepStick stepper drivers on it operates the three NEMA-11 motors. Meanwhile, the kids interact with a 7” touchscreen powered by a Raspberry Pi.

Once the kid selects what to engrave, motors move the piece of acrylic against a rotary tool’s milling bit, carving the acrylic as instructed. These cards are then equipped with watch batteries and LEDs to light up.

The touch screen is key. Bummed out by basic CNC machines that were difficult to use — like hobbyist 3D printers with a newbie-befuddling interface — [moritz.messerschmidt] went out of his way to make the interface kid-friendly, with just a simple set of choices necessary for creating one’s own name badge.

Is this a feature-packed CNC machine with all the bells and whistles? No, but that’s not the point. The purpose of the Badgemaker is to introduce a new generation to personal fabrication technology. It’s a toy, but that’s the point: a CNC machine that’s so easy to use, even a child can do it.