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instructablesBuilding Your Own CNC Router/milling Machineby TrochilidesignAlready when I was little I was thinking of making amachine which could make things! A machine whichwould give me the opportunity to create products forin and around the house. Years later I stumbled onthe words 'Computer Numerical Control' or morespecifically the CNC milling machine. After I foundout people were able to build one themselves in theirown shed, I knew it!For three months I tried to find the proper parts (Adremeltool, drawer slides, pieces of wood, etc.), but Ididn't really know how to build a CNC. The idea fellinto oblivion.In August 2013 the idea to build a CNC millingmachine captivated me again. I just finished the firstyear of my bachelor in Industrial Design, so I wasconfident enough to start a build. The real differencebetween now and 5 years ago was, I learned to workwith metal on manual milling machines and lathesand above all I had the right tools to design amachine.This Instructable will show you how I built my CNCmilling machine. I know a lot of CNC dreamers do nothave the knowledge or tools to build a full metalmachine. I still think and hope this Instructableinspires you to make your own machine. I include allof the necessary steps I went through in designingand building this CNC milling machine.Building Your Own CNC Router/milling Machine: Page 1

Step 1: The Design and CAD ModelIt all started with a proper design, in my case a fewsketches to get a good feeling for the dimensions andshape. Quickly after the sketching phase came theCAD model. I created my model in SolidWorks. If youplan to design your own machine I recommend aparametric CAD-modeling tool. Your machine willmost likely have a lot of parts which have to fittogether neatly, sometimes with some strangedimensions (for example pre-ordered parts). After allthe parts were modeled, technical drawings weremade. I used these drawings to machine all of thecustom parts on the manual lathe and millingmachine.Since I'm a lover of good designed tools, I tried tomake maintenance and the possibility to adjust thingson the machine as easy as possible. Bearings couldhave been integrated in the machine, but I chose toplace them in separate bearing blocks (in case itneeds to be replaced in the future). Keeping yourmachine clean is very important too, so guiderails areall accessible (in case of the x-axis by detachingsome cover plates)Step 2: The FrameThe frame provides the machine a rigid basis, notonly to place it in your workshop but also for workingon. To the frame the gantry will be mounted on slidingrails and later on a work surface. It also houses thestepper motor and spindle for the x-axis. I constructedmy frame from 2 Maytec 40x80mm profiles, 2endplates (both 10 mm thick aluminium), 4 cornerpieces and a square structural piece.All of the profiles are sawed right-angled andafterward milled exactly square. With the cornerpieces a heavy (well relatively lightweight; it's allaluminium) frame was bolted together. The squareframe made from the smaller profiles were mountedwith 4 milled blocks (aluminium) on the inside of theMaytec profiles.Since the frame sits beneath the worksurface dustcould fall down on the guiderails (you want to keepthem clean, more about that in step 5). To preventthis, dust covers were made and mounted around theguiderails. A angular profile mounted with brassmilled t-nuts onto the may tech frame and 2mmaluminium plates mounted in the milled pockets onthe endplates.On both endplates bearing blocks are mounted for thespindle. They were hand milled and lathed to the righttolerances. On the front endplate mounting slots forthe stepper motor were milledBuilding Your Own CNC Router/milling Machine: Page 2

3645232111. Milled parts for dust covers2. Linear guide rails; discussed in step 53. Maytech Aluminium 40x80mm extruded profile4. 40x40mm aluminium profile for a rigid structure5. 90degree angle pieces6. Lots of T-slots for T-nuts. Mounting things to the frame is just peanuts1. Dustcovers mounted2. Linear guiderails with the runner blocks slided on3. The square structure assembled and mounted in theframe11. DustcoverBuilding Your Own CNC Router/milling Machine: Page 3

Step 3: The GantryThe gantry is the bridge between the x-axis guiderailsand supports your milling motor above the workpiece.The higher you make it, the thicker the workpiece canbe. There is however a disadvantage of high gantries.They work as levers on the guiderails and on theother hand the side plates tend to bend more easilyby making them longer.Most of the work I planned to do with the CNCinvolved milling aluminium parts. An average vise forthe machine would be 60 mm high. Since the thickestblocks of aluminium easily available for me would be60 mm high as well, I chose to space between thework surface and the piece of metal, which could hitthe workpiece first, to be 125 mm. This gave me astarting point for the side plates. Since I wanted thecenter of an end mill hovering over the center of therunnigblocks (from the machines side view), the sideplates had to be placed at an angle. Solidworkshelped me to convert all of the measurements into thefinal parts. Because of all the complex dimensions Idecided to mill these parts on an industrial CNC mill,this also gave me the opportunity to round all of thecorners (would have been very hard to mill on amanual mill).formed out of an 5mm thick U-profile. It is mountedbetween the side plate with the help of two simplemounting blocks. On the inside the U-profile housesthe y-axis spindle. Which is again supported by thesame bearing blocks used for the x-axis. They aremounted on the outside of the side plates.Beneath the main frame a plate was mounted on theunderside of the gantry's side plates, giving amounting point for the x-axis spindle nut.The part which supports the y-axis guiderails is11. Sideplates of the gantry; they were CNC milled on an industrial machine.Building Your Own CNC Router/milling Machine: Page 4

Step 4: Last MovementThe last movement is what I call theStepermotorhousing for the z-axis (plus the z-axisitself of course). It is constructed out of a frontplatemounted on the y-axis linear guiderails, 2reinforcement plates, a motor mount and a backplate.On the front plate 2 linear guiderails were mounted forthe z-axis onto which the Mountingplate for the millingmotor was placed with the runner blocks.The motor mount has the bearing for the z-axisspindle fitted into it. So I didn't use a bearing block forthis spindle and is only supported on the top. he lowerend is floating behind the mounting plate for themilling motor. The spindle nut for the Z-axis wasdirectly bolted on the mounting plate for the millingmotor.The backplate provides a spot for the y-axis spindlenut to be mounted; it is mounted on the inside.All of the custom mechanics are now ready. The CNCis assembled with the guiderails, spindles and a lot ofbolts ;-)Building Your Own CNC Router/milling Machine: Page 5

Step 5: Guide RailsSince your endmills need to move in 3 directions, themachine guides them with its guide rails. The guiderails provides the machine its rigidity in all directionsexcept the one it moves in. You want them to let themachine only move in the preferred direction. Anybacklash in other directions results in inaccuracies inyour workpieces.On my machine I wanted to use guideways supportedon the full length of the rail, reducing the risk fordeflections on the longer axes.In my opinion some kitchen drawer slides arepreferred above the hardened steel rods which aresupported on the end (yes! they will deflect). Sinceyou are constantly fighting the forces from theendmills against the material of the workpiece, a lot ofsupport is recommended.I chose the most expensive option; profiled linearguide rails with runner blocks. The are designed toreceive forces in all directions. In the third picture youcan see the looping bearing balls, they are positionedon both sides of the profile. All with a tangent 45degree relative to each other, giving it the ability tohandle high loads.To get all guiderails perpendicular and parallel toeach other they were all aligned with a dial indicator(with a maximum difference of 0,01 mm). If you spentyour time on this part, the machine will perform verywell in accuracy!Building Your Own CNC Router/milling Machine: Page 6

Step 6: Spindles and PulleysThe spindles translate the rotational movement fromthe stepper motors into a linear movement. Whenbuilding your machine, you can choose betweenthree different version; leadscrews or ball screws,either in metric or Imperial configuration. The maindifference between leadscrews and ball screws is theaccuracy and friction. Leadscrews tend to have a lotmore friction and are less precise than ball screws. Ifyour looking for a very accurate machine without anybacklash, you should definitely consider ball screws.However, they are relatively expensive!drivenut which reduce friction and are approach abacklash free system. You can order the drive nutshere: http://www.mixware.de/index.html\Both the ends of the x- and y-axis have to be turnedto size to fit the bearings, pulleys and clamping nuts.Since the z-axis spindle is only supported on one andwith a bearing, it is turned on only one side.The pulleys are drilled to the turned shaft size (in mycase 8 mm) and provided with a M4 setscrewperpendicular to the shafthole.I chose to use leadscrews with a special plasticBuilding Your Own CNC Router/milling Machine: Page 7

Step 7: WorksurfaceThe work surface is the place you will clamp yourpieces of material on. On a lot of professionalmachine a T-slotted bed is used, giving you theoption the use T-nuts and bolts to clamp yourmaterials or vices. I chose to use a square piece of18 mm birch-plywood on which a screw the materialsand replace it when needed. An affordable worksurface! You could also use Mdf with anchor nuts andbolts. Try to avoid screws and nails in Mdf, it doesn'tgrip them as good as a plywood board.The work surface could be milled flat by the machineitself after you've completed it. Your first project :-)Building Your Own CNC Router/milling Machine: Page 8

Step 8: Electrical SystemThe main components in the electrical system are:-Stepper motorsYou can of course also put together your own set.Since I could not wait to sartup the machine Itemporarily mounted all the drivers and power supplyon a open board. The enclosure is in the making.-Stepper driversSince a few years it is also possible to connect aCNC very easily via USB. The UBS-breakout boardson the market generally come with their ownsoftware. I chose to use the parallel printer port foundon most older PC's. I do not intend to use a newcomputer in a room full of dust, oil and aluminiumchips-Powersupply (or 2)-Breakoutboard-Computer-And last but not least: Safety first; a emergency stop;-)I chose to buy a complete set on Ebay with 3 Nema23 stepper motors, 3 suitable drivers, a breakoutboard and a 36 V power supply. I use a step downconverter to convert the 36 volt DC into 5 Volt DC.Since I had a lot of difficulties in finding a properscheme with the needed components, I tried to makeeverything clear in the infographic above (you canalso download the PDF and zoom in on the HN/J01T/HVS1FHDO/FHNJ01THVS1FHDO.pdf DownloadStep 9: The Milling MotorSince we want to remove material from the piece weclamp to the work surface, we need something thatdrives the cutting bits; i.e. the endmills. The millingmotor will spin the cutters at low or high speeds.From a simple Dremeltool to a High frequencySpindle of several kWatts. For our machine size aKress spindle is very convenient to start with. If youwant to improve your machine, a reliable Hf spindlewill please you. It all depents on the amount of moneyyou can afford to spent on it.Try to find something with the ability to use differentsized collets.Building Your Own CNC Router/milling Machine: Page 9