CNC Mill for under $100

[Music] in this video i'm going to show how i built a cnc mill for under 100 using 3d printed brackets and leftover parts the mill can actually cut aluminum which will allow me to build a lot of cool stuff in the future the parts are a little bit rough but for the price i'm pretty happy with them the project started when i went shopping for the cheapest cnc machine i could find yeah too much still too much too much at 165 dollars this is the absolute cheapest i could find yeah that's still too much the cheapskate in me thinks there's a better way to do this so let's check the junk drawer this looks pretty promising after laying everything out and taking inventory i found i had most of the parts needed to build a simple cnc with the exception of a spindle a build plate and a couple of bearings then i came up with this design for the full machine the 3d printed parts which are shown in blue tie everything together and also house the electronics it took me about three days to print everything all right let's start building [Music] [Music] do [Music] [Music] so [Music] [Music] do [Music] [Music] [Music] [Music] do [Music] [Music] now i need a spindle so once again being a cheapskate i got the most basic thing i could possibly find which was basically a brushed dc motor with a collet slapped on it i'm not going to sugarcoat it this thing is terrible it's incredibly loud vibrates like crazy and without even using a gauge you can tell that the shaft is crooked honestly it might be better to catch a wild beaver and duct tape him to a z-axis carriage because it would be about as accurate as this so-called spindle but at the end of the day it does cut material so whatever [Music] do [Music] do [Music] at this point i need to set up the electronics before i go any further in the build the supply voltage of the machine is mainly dictated by the spindle which requires 24 volts i'm using a 24 volt 20 amp power supply which is way beyond what the machine needs but it's what i had sitting around the brain of the machine is an arduino uno which will run grbl firmware the grbl firmware allows me to control the machine from a usb connection to my computer and send it g-code however the arduino has a maximum input voltage of 20 volts so i'll be using a butt converter to step down the 24 volts to around 12 so that it's well inside the range of the board's regulator i really don't like this overly bulky barrel connector on the board it's a big annoying multi-amp connector for a device that really only pulls a few milliamps so i'm going to desolder it in its place i'm just going to directly solder in the output of the buck converter i wound up with this goofy looking abomination now let's make sure it works no smoker explosions looks like we're good the next step is to connect the stepper driver breakout board this will allow the stepper motor drivers to piggyback directly on top of the arduino board at this point our fancy block diagram looks something like this the stepper motor driver's logic is driven by the arduino but the bulk power comes from the 24 volt rail in a minute we'll connect the stepper motors to the drivers but first we need a way to control the spindle to do that i created this brushed dc speed controller with a 555 timer and a mosfet the resistors and capacitors connected to the timer set its output at about 500 hertz there's opposite direction diodes on either leg of the potentiometer so the total round trip resistance for a charge discharge cycle is the same which fixes the frequency however the duty cycle of the output changes as the potentiometer is adjusted a mosfet acting as a low side switch is turned on and off through the gate resistor which modulates the spindle motor and of course a flyback diode is in place to protect the circuit from the motor's back emf here's a look at the timer output on the scope the duty cycle can be varied from about 7 to 99 percent now let's see what it does hooked up to the motor [Music] okay perfect now i can start putting all the electronics in an enclosure box and then wire everything up [Music] [Music] [Music] do [Music] [Music] [Music] so that completes the electronics portion of the project to recap with a slightly cleaner diagram 24 volts comes in through the main power switch illuminating the 24 volt indicator light and powering the buck converter which supplies 12 volt power to an arduino uno and a cooling fan the arduino is connected to a computer by usb a stepper motor breakout board is connected to the arduino which houses three a4988 stepper motor drivers that control the x y and z axis motors these drivers are supplied power by the 24 volt rail the second switch supplies power to the motor speed controller and motor indicator light and the speed controller of course modulates the spindle motor itself the last thing i need to do before i fire up the machine is attach the build plate which is this quarter inch thick chunk of aluminum after a little bit of drilling and tapping i've got holes for mounting the y-axis carriages and lead screw nut and threaded holes for mounting a waste board on top now the machine is assembled and ready to go so i just need to upload the firmware to the arduino and i can start controlling it with g-code from my laptop i'm going to use grbl which is an open source firmware for cnc machines that fits on an arduino uno all i have to do is download it add it as a library in the arduino ide and upload it to my board to control my machine and send g-code i'm going to use universal g-code sender which is also open source this has all the basic functionality you need to run a cnc machine and it's really easy to use let's power the machine up and give it a quick test i hand wrote some g code for the x and y axes to move in a couple circles to make sure they work right looks like it's doing what it's supposed to let's do a quick dimensional test with a simple hole pattern [Music] [Music] looks good to me now let's try something a little fancier i use the free trial of easel to generate code for subsequent projects because it's browser based and extremely easy to use which is good for me because i have no experience with cam programs it's got a ton of pre-made geometry patterns shape generators etc which makes it great for the artistically inclined but for more serious engineering type cam i'll probably have to use a different software in the future i'm going to try to make this design here i don't want to risk any nice material yet so i'll start with this old piece of 2x4 from my scrap pile i'll start by facing the surface and part of the sides to clean it up a little bit unfortunately this takes quite a while because i don't have a proper facing tool just a 1 8 end mill after facing i apply a little bit of wood stain so there will be some contrast between the surface and the cutouts now for the actual engraving [Music] all right that worked perfectly because it's soft pine wood the cut edges are very stringy and splintered in some places but the result shows that the machine is working exactly as intended so let's move up to a nicer material i'm going to try to make this simple ball maze out of a red oak board because oak is a hardwood it's a lot less mushy than pine so there should be way less stringing and splintering allowing for a nicer finish let's give it a try [Music] oh [Music] that came out pretty nice much cleaner than the pine from the scrap 2x4 the rounded edges you see are from sanding i did by hand let's give this thing a few coats of wood stain and polyurethane [Music] do [Music] okay i'm very pleased with that result but now to the important question can the machine cut metal i'm almost certain it won't cut steel but it can probably handle aluminum so let's do a few tests this is a sheet of 6061 aluminum i have a two flute 1 8 inch end mill running around 18 000 rpm and i cut depth set to 0.2 millimeters with a feed rate of about 100 millimeters per minute the moment the tool contacts the metal the head pops up and the cutter is just barely skimming the surface of the aluminum [Music] then when it comes out the other side there's a very nasty thump as it pops back down to its original height so there's definitely a problem with the rigidity of the machine the same thing happens with the cut depth set at 0.4 millimeters but this time it actually does take a bite out of the material and you can hear and see it cutting this time it's even more violent popping off the material as the upward pressure is relieved here's the result of that test the spindle and stepper motors definitely have plenty of power to cut through the aluminum but the amount of play in the machine combined with the vibration of the cheap spindle motor caused the tool to rattle around making a very rough cut you can see here what a huge amount of slop the head has i can probably move it around two or three millimeters in any direction on a good mill the head should be absolutely rock solid this comes from backlash in the z and x lead screws combined with the fact that the eight millimeter rails are thin enough that they'll flex under a little bit of load the backlash could be eliminated by tightening two nuts against each other on the lead screw at the expense of extra friction as for the rails they just need to be a whole lot thicker or be replaced by true linear rails bolted to a frame keeping these limitations in mind i'm going to go ahead and try to cut some aluminum parts and see how good or bad they turn out the first one is a simple sprocket cut out of 1 16th aluminum sheet that actually came out surprisingly good i have no idea how tight the tolerances are on this thing but the shape looks perfect and it's definitely usable for hobby purposes let's try something much more aggressive now i want to see if i can hog out this one-inch thick block into a shape [Music] [Music] and here's the end result i wanted to cut this gear shape all the way through the thickness of the material but there was a glitch at some point which caused the machine to drive the tool down into the side making this gouge and of course as expected the surface finish of the part is still very rough overall though this machine definitely exceeded my expectations this is the first cnc mill i've owned or built and it was a total success despite the limitations the total cost of the project came out to 74.92 the only items i bought were the spindle build plate linear bearings and a pack of extra end mills however after seeing the capabilities of this machine i'm definitely going to invest in upgrades so stay tuned for part two of this video sometime in the future thanks for watching

Channel: Hyperspace Pirate

Views: 2,390,981

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Id: R29G3hUiZnU

Length: 18min 4sec (1084 seconds)

Published: Sun Feb 27 2022