CNC Basics - Everything a Beginner Needs To Know

Summary

This video is an introduction to CNC machines for beginners. It explains the basics of CNC technology, specifically focusing on CNC mills and routers. Viewers will learn about the essential parts of a CNC machine, the design and setup process, tool paths, work holding, and the importance of offsets and feeds and speeds. The host also discusses the differences between CNC machines and 3D printers, along with practical tips for getting started with CNC machining. The video emphasizes that CNC machining involves more hands-on control and precision compared to other automated processes.

Takeaways

• 🛠️ CNC stands for Computer Numerical Control, a technology that moves machinery to cut materials.
• 🔧 CNC machines come in different types, including routers (for wood) and mills (for metal), though there is overlap.
• 🖼️ A CNC machine typically has a bed for material and a cutting head that moves on three axes; more advanced machines use four or five axes.
• ⚙️ The cutting tools used are called end mills, which differ from drill bits and come in various shapes and sizes.
• 🖥️ CNC machining involves several steps: design, tool path creation, work holding, and setting offsets.
• 📐 Design for CNC is different from 3D printing and often involves CAD software to account for machine limitations.
• 🚀 Tool paths and speeds must be calculated and programmed manually, often with help from CAM software.
• 🔩 Work holding secures materials during the cutting process and is critical to ensure the machine doesn't crash.
• 📏 Offsets, or datums, tell the machine where the material is placed before starting the cut.
• 🧹 Post-milling, the part often requires cleanup, such as sanding or deburring, to achieve a finished look.

Q & A

What is a CNC machine and how is it defined?

A CNC machine, or Computer Numerical Control machine, is a device that uses computer programming to control its movements. This term is broad and can refer to various devices such as CNC mills, routers, plasma tables, 3D printers, laser cutters, and vinyl cutters. The main commonality is that they all use computer control to guide their operations.

What are the differences between CNC routers and CNC mills?

CNC routers are typically used to cut wood and are generally lighter in build, while CNC mills are more robust and designed for cutting metals. Despite these distinctions, there can be overlap; some people use CNC routers to cut metal and CNC mills to cut wood. The primary difference lies in the intended use and build of each machine.

What basic components do all CNC machines share?

Most CNC machines, regardless of type, have a bed (or table) and a cutting head (spindle or router) that moves in at least three axes. Some machines may offer more complex movements with 4, 5, or more axes. These components allow the machine to cut, carve, or engrave materials according to programmed paths.

How does designing for a CNC machine differ from designing for a 3D printer?

Designing for a CNC machine requires considering the cutter’s limitations, such as the inability to create overhangs unless using more complex multi-axis machines. While 3D printers build objects layer by layer, CNC machines remove material, making the design process more about managing tool paths and material removal strategies.

What is CAM and how does it relate to CNC machining?

CAM, or Computer-Aided Manufacturing, involves creating the tool paths that a CNC machine will follow. Unlike 3D printing, where the software automatically generates paths, CNC operators must manually set parameters like tool speed, feed rate, and path direction. CAM software helps in designing these paths and ensuring precise execution.

Why is work holding important in CNC machining?

Work holding ensures that the material being cut remains securely in place. Because CNC machines apply forces in multiple directions, improper work holding can lead to movement or dislocation of the material, causing inaccurate cuts or potential damage to the machine and workpiece.

What are offsets and why are they crucial in CNC machining?

Offsets, or datums, refer to the process of telling the CNC machine the exact location of the material on the bed. Since the machine has no inherent knowledge of where the material is placed, setting offsets accurately is crucial to ensure the tool paths align correctly with the material. Incorrect offsets can lead to crashes or misaligned cuts.

What is tool length compensation and why is it necessary?

Tool length compensation involves informing the machine about the length of the cutting tool in use. This is necessary because different tools have varying lengths, and the machine needs this information to maintain the correct cutting depth and avoid collisions. It can be done manually or with automated touch-off devices.

What is fixturing and how does it differ from standard work holding?

Fixturing is a specific type of work holding designed to enable the repeated, accurate placement of the same workpiece for multiple cuts. It is particularly useful for production runs where the same part needs to be machined multiple times without re-calibrating or re-setting the machine for each piece.

What factors should be considered when choosing a CNC machine?

When choosing a CNC machine, consider what materials you plan to cut (wood, metal, etc.), the size of the workpieces, and your budget. For wood, CNC routers are typically more suitable, while CNC mills are better for metals. It's important to match the machine's capabilities with your intended projects.

Outlines

00:00

🔧 Introduction to CNC for Beginners

This paragraph introduces the video, aimed at absolute beginners who are curious about CNC machines but have little to no knowledge of how they work. It highlights that while experienced users may not find new information, novices will learn about CNC machines, their purpose, and basic functionality. The focus will be on CNC mills and routers, explaining how they differ from other CNC machines like plasma tables and vinyl cutters.

05:05

⚙️ Anatomy of CNC Machines

This section breaks down the basic anatomy of CNC machines, particularly mills and routers. It explains how CNC machines can vary in size but typically have a bed and a cutting head that moves to perform cuts. The video focuses on 3-axis systems, though it mentions that more complex machines can use up to five axes. The cutting head, often referred to as a spindle, holds tools called end mills, which differ from standard drill bits in their cutting geometry. Various types of end mills are used for different tasks.

10:07

🖊️ The CNC Process vs. 3D Printing

This paragraph contrasts the CNC process with 3D printing, pointing out that CNC is far more complex. Unlike 3D printers, which automate most of the process, CNC users must manually set parameters such as spindle speed and tool movement. Additionally, material must be mounted correctly, and the machine needs to be programmed to understand the layout of the material. The paragraph emphasizes the importance of planning tool paths and work holding for successful CNC operations.

15:07

📐 CNC Design and Tool Path Setup

This part covers the design and tool path creation for CNC. Users must account for the limitations of their CNC machines, such as the inability to cut overhangs on a standard 3-axis system. CAD software like Fusion 360 or SolidWorks is typically used for designing projects, although 2D vector software can also be applied. Users must then plan the tool paths, telling the machine how fast the tool should spin, how much material to cut, and when to switch between tools for different tasks.

🔨 Work Holding and Material Setup

This section explains the concept of work holding, the process of securing material onto the CNC machine for cutting. Proper work holding is essential, as the material can experience forces from different directions during the cutting process. Clamping systems are commonly used, but users must ensure that the cutting head does not hit the clamps. The video provides tips on various work-holding methods, including using screws or double-sided super glue for CNC routers.

📏 Offsets and Material Positioning

Here, the video introduces offsets, which are crucial for the machine to know the exact position of the material. Offsets (referred to as 'datums' in the UK) help define the zero point for the cutting process. Users must align the cutting head to this point manually or through the machine's interface. The accuracy of material measurements and setup is vital to avoid crashes or misalignments during the cutting process.

✂️ Tool Length and Multi-Tool Usage

This section focuses on tool length and the process of switching between tools during a CNC job. Since the machine has no awareness of the tool’s length, users must manually input this information or use a touch plate to measure it. For projects requiring multiple tools, users must tell the machine when to switch tools and provide accurate measurements to avoid errors. The video emphasizes the need to recalibrate for each tool change during a job.

🔄 Fixturing for Repetitive Tasks

Fixturing is introduced as a method of work holding specifically designed for repetitive tasks. By creating fixtures that hold materials in place for multiple cuts, users can streamline the CNC process for batch production. Fixturing reduces the need to reset offsets or create new tool paths for each individual job, making it efficient for producing the same object multiple times.

🧹 Post-Cutting Cleanup and Finishing

This part covers the cleanup process after a CNC job is completed. Most CNC projects, especially those involving wood, require some form of finishing, such as sanding or deburring to smooth out edges. Even in metalworking, parts may need additional steps like polishing or sandblasting. The paragraph emphasizes that CNC machines do not always produce finished parts, and manual post-processing is often necessary.

💡 Final Thoughts and Choosing the Right CNC Machine

In conclusion, the video recaps the basics of CNC and encourages viewers to consider key factors before buying a machine, such as the type of material they plan to cut and the machine’s size. It explains that while there is overlap between CNC mills and routers, selecting the right machine depends on specific project requirements and budget. The video wraps up with a reminder to subscribe and stay tuned for future content.

Keywords

💡CNC Machine

A CNC (Computer Numerical Control) machine is a device controlled by a computer that directs the movement of cutting tools to shape or modify materials. The script highlights its versatility, from cutting wood (CNC router) to metal (CNC mill), and includes a range of machines like plasma tables, vinyl cutters, and even 3D printers.

💡CNC Mill

A CNC mill is a type of CNC machine typically used to cut and shape metal. It is heavier and more rigid compared to CNC routers, making it suitable for precise cutting of harder materials like steel or aluminum. In the video, the CNC mill is compared to the CNC router, which is usually used for cutting wood.

💡CNC Router

A CNC router is a CNC machine designed predominantly for cutting softer materials like wood. The script emphasizes the router's use in woodworking projects, contrasting it with the CNC mill used for metal. However, there is overlap, as some CNC routers can cut metal under certain conditions.

💡Spindle

The spindle is the motorized cutting head on a CNC machine that holds and rotates the cutting tool (end mill). It plays a central role in cutting or shaping materials, and the video explains that spindles can vary in design, from purpose-built motors to hardware store palm routers.

💡End Mill

An end mill is a cutting tool used in CNC machines to carve out material. It resembles a drill bit but is specifically designed for cutting and milling, with different shapes and sizes available depending on the precision needed. The video explains that smaller end mills are used for fine details, while larger ones remove more material quickly.

💡Feeds and Speeds

Feeds and speeds refer to the rate at which the CNC machine’s cutting tool moves and the speed at which the spindle rotates. Proper feeds and speeds are crucial for effective cutting, as explained in the video, where improper settings can lead to tool damage or poor-quality cuts.

💡CAM (Computer-Aided Manufacturing)

CAM refers to the software used to design the tool paths for CNC machines. It tells the machine how to move, cut, and process materials. The script discusses how CAM requires users to input precise details such as the direction, speed, and depth of the cutting tool, making it more hands-on than 3D printing.

💡Work Holding

Work holding is the method used to secure materials in place during CNC machining. The video explains the importance of securing materials to prevent movement while cutting, using clamps or other fixtures to hold the material tightly to avoid machine crashes or errors.

💡Offsets

Offsets are used to tell the CNC machine where the material is located within the workspace. In the video, the speaker explains how the machine doesn’t automatically know where the material is, so the user must input precise coordinates to ensure accurate cutting.

💡Fixturing

Fixturing refers to a specialized form of work holding that allows for repeated machining of the same part without recalibrating the machine each time. In the video, fixturing is mentioned as a helpful technique for mass-producing identical parts efficiently.

Highlights

Introduction to CNC machines for beginners, covering basic concepts and the differences between CNC routers and CNC mills.

Explanation that CNC stands for Computer Numerical Control, which refers to machines that follow digital instructions to move and cut materials.

Distinction between CNC routers (mainly used for wood) and CNC mills (typically used for metal) and how these can overlap in certain use cases.

Overview of basic CNC machine parts, including the bed and cutting head, and how these components move along multiple axes to perform cuts.

Clarification on spindle and end mills: the cutting head (spindle) holds specialized cutting tools (end mills), which are distinct from drill bits in shape and purpose.

Introduction to the CNC design process, emphasizing that users must plan the tool paths manually, unlike in 3D printing where this is automatic.

Explanation of CAM (Computer-Aided Manufacturing) software and how it helps generate the tool paths for CNC machines, which dictate how the machine will cut the material.

Importance of work holding: the process of securing material on the CNC machine to ensure stability during cutting.

Introduction to offsets (or datums): specifying the exact location of the material on the CNC bed so that the machine can accurately perform the cuts.

Steps in the actual milling process, including how to account for tool length and the need for multiple tool changes during a job.

Discussion of fixturing, a type of work holding used for repeating cuts in mass production.

Explanation of the cleanup process after a CNC job, such as deburring and sanding, especially for wood and metal parts.

Final advice for CNC beginners: considerations when purchasing a machine, including the type of material to be cut and budget constraints.

Tips on feeds and speeds: setting the right parameters for cutting speed and tool rotation based on material type and machine capability.

Encouragement for beginners to dive deeper into CNC with additional resources, such as tutorials and books available for further learning.

Transcripts

welcome back to the channel today i have a  very fun uh video for you we're going to be  

going back to the basics on cnc now this video  is for absolute beginners who have heard those  

words before or maybe seen some machines around  and thought that looks like fun but they have  

no idea how it works or what's involved if  you're already cutting things on a cnc machine  

then there's probably not going  to be much here for you that's new  

but for the rest of you i encourage you to  stick around you'll walk away at the end  

understanding a lot better what cnc machines are  how they work and how to get your jobs done all  

right so let's start off first with what the heck  is a cnc machine you've probably heard a lot of  

names tossed around cnc mill  cnc router cnc plasma table well  

cnc actually is just a reference to the technology  used computer numerical control that moves the  

mechanism around it's a really really vague term  technically your 3d printer is a cnc machine  

your laser cutter is a cnc machine cnc routers  and mills of course are cnc machines plasma tables  

vinyl cutters all those things are technically cnc  machines for the sake of this video we're going to  

focus on cnc mills in cnc routers now even those  even though you can kind of define them strictly  

they get muddy too generally speaking when you're  talking to a maker about a cnc router that is a  

system that's predominantly used to cut wood  when you talk about a cnc mill that's generally  

a system that is much beefier and heavier and  intended to be cutting metal there's lots of  

overlap you'll see people cutting metal on routers  made for wood you'll see occasionally people  

cutting wood on a metal cnc mill really for the  sake of this video you don't need to worry about  

that we're just going to be talking about the  extreme basics of cnc mills in cnc routers [Music]  

so let's start with an anatomy lesson cnc mills  come in all shapes and sizes there are itty bitty  

tiny ones like this little tormach here and  there are some the size of entire buildings  

they all have some things in common though  some basic parts that you'll see on every  

cnc router and mill in some form or another some  are enclosed some are not but what you'll see on  

almost all of them is there is a bed of some kind  and a cutting head that can move around to do the  

cutting and by some combination of the bed and  the head moving or maybe just the head moving you  

have the ability to cut on three axes of course  there are machines that go up five axes four axes  

and more but again we're staying basic here this  cutting head here can be referred to as several  

different things often you'll hear the term  spindle which is a kind of purpose-built motor  

just for being used on on these cutting machines  or sometimes you'll see it's literally just  

a router like a palm router you would buy at a  hardware store strapped onto the gantry the tools  

that mount in here that do the actual cutting are  called end mills they look kind of like drill bits  

but the actual shape and geometry of the little  cutting edges is different than your standard  

drill bit these are purpose built for the  job of being run on a mill to cut materials  

they come in a wide variety of shapes and  sizes all the way down to itty bitty tiny  

ones for getting super fine details up  to you know on a very large machine you  

could have something a foot wide that is  there just to take off lots of material

now that we've covered kind of the most basic  anatomy of a cnc machine let's talk about the  

actual process of using one if you're familiar  with 3d printing you could be forgiven for  

thinking that it's the same but it's actually  quite different um you know in 3d printing you  

download your file you throw it in a slicer you  select the quality you go to your machine you  

load your filament you hit go and more or less  it prints what you want you know excluding any  

failures in cnc milling machining routing there's  a lot more to it first you start off by designing  

sometimes people design in 3d sometimes  people actually distill design in 2d  

then you go into your tool path construction you  use software to create the paths that the head  

is going to have to move that's right it's not  like a 3d printer that figures it out for you you  

actually have to figure it out for yourself you  have to tell it how fast to spin the spindle how  

far to move what direction to move and things like  that then there's actually mounting your material  

onto the machine that's called work holding  after that you have to tell the machine where  

everything is it doesn't know where everything  is and then finally you run your job after  

you've cut it then you need to clean it up  we'll go through all that let's jump into it

design for cnc well it's pretty different than  designing for a 3d printer for one thing you  

have to think about the fact that on a standard  3-axis machine your cutter is coming straight  

down at your material so it can't do things  like get underneath the material over here  

so you really can't do things like overhangs at  all unless you're going to get into more complex  

things like moving your material around of course  that excludes fancier machines that have multiple  

axis heads people still design for cnc in 2d what  i mean by that is they'll open up a program like  

adobe illustrator or escape and they'll just make  lines and use those as the basis for the next step  

so designing for cnc is different than designing  for a 3d printer and typical tools people use  

for that are cad occasionally like i said  you'll see people using vector software  

like inkscape but typically they'll use cad like  you know fusion solidworks stuff like that you  

can design in 3d you just have to be aware  of the limitations of your machine [Music]

so after you've designed your file you're ready  to cut it you can't just tell the machine to go  

unlike 3d printers you have to actually tell a  cnc machine exactly what you want it to do you  

have to tell it how fast to spin the tool how fast  to move the tool and how much of the tool should  

be engaging with the material at a time that's  a lot of stuff to keep track of there are fancy  

calculators out there that can help you figure  all those things out and the manufacturers of  

these tools often publish kind of a best practices  that you can use depending on your machine this  

is often referred to as feeds and speeds those  numbers of how fast it spins and how fast it moves  

those are feeds and speeds the general process of  coming up with all of those paths is called cam so  

if you look around or google the term cam software  what you're doing is you're finding software that  

allows you to come up with those tool paths some  software does things a little bit more automated  

and helpful like in fusion and i believe  solidworks also has some stuff where you  

can kind of choose a shape and tell it you want  it to do kind of a rough milling of that shape  

and it will figure out the best tool paths for  you another thing that you have to consider when  

you're doing cam for a cnc machine is the fact  that it is going to have to use multiple tools  

most likely let's say you want fine detail it  doesn't make any sense to do your entire cut with  

a super tiny little end mill because it'll take  ages and ages instead you start with something big  

you take away all the material you can leaving a  little bit behind and then you come back with your  

tiny end mill well you're gonna have to go into  the software into your cam software and tell it  

cut with this tool this way then switch  tools and use this other tool this other way  

it takes a lot of practice there are tons of  tutorials out there to help you though as well  

as books we've got some books in our maker  shed that'll walk you through that process  

some software for doing cam you know fusion 360  has it solidworks is getting it solid works for  

makers it's getting it this summer there's  pi cam freecad has a plug-in that will do cam  

i think open builds also has some software  that will do cam lots of options out there

after you've got your tool path set up you've  done your cam you actually have to put your  

material in the machine that uh it sounds easy  but it's actually more complicated than you would  

think this is a whole area typically referred  to as work holding where you're securing your  

material into the machine your material is going  to experience forces both down and up depending  

on how the tool is cutting it as well as side to  side so you have to fasten it down really well  

typically you see this done by some kind of  clamp system but with a cnc router you have to be  

extremely careful because the cutting head as it  moves around can theoretically hit your clamps  

so there are lots of workarounds for this i  shared a tip i learned you know from nyccnc  

on how to do like a double-sided super  glue kind of rig there are wooden screws  

you can actually use to stick through uh  sheets of plywood so whenever the cutting  

tool hits it it's no big deal there there  are lots of options out there it's called  

work holding and you're gonna have to get  familiar with it if you're gonna do cnc [Music]

up next are offsets so you've got your  file prepared you've got your material  

on the machine you think you're ready to go not  quite the thing you have to do next is tell the  

machine where the material is here in the states  we call that offsets i've heard it referred to as  

datums in the uk if i'm wrong sorry about that  but here in the states we call them offsets when  

you turn your machine on first it's probably  going to want to home itself kind of like a 3d  

printer not all machines do this but a lot do and  that tells it where the edge of its bed is where  

the edge of its work area is but your machine has  no idea where that material is that you put in it  

would it know right so what you have to do is you  have to tell the machine where that material is  

when you are doing your cam programming you chose  a point on your machine to be the zero point um  

and and that's going to be where you will tell  the machine this is that point i told you about  

and then it'll kind of know where your  material is okay so you know you put  

a shoebox size thing in there you told it  this corner is the point you're going to do  

you're going to move your machine over there  you're going to bring the tool all the way down  

you're going to touch that corner and you're  going to tell the machine this is my work  

offset it it gets confusing with all the names  but basically you're just telling the machine  

where your material is otherwise it would have  no idea this is also why it's extremely important  

that you measured your material accurately you  have the same material you programmed into it  

and things like that your machine has no idea  it's going to run the program and if you have  

for example a tougher material or more material  than you programmed it for it's going to crash

now for the fun part the actual milling you've  got the program in there you've told your machine  

where the material is the materials held down  solidly and now you get to start cutting stuff  

absolutely it's fun it's the best part but there's  some stuff that goes along with that first off  

your machine has no idea what's the end of the  spindle it has no idea what's out there so you  

actually have to tell it how long that tool is  different machines have different ways of doing  

this sometimes you program it in whenever you're  doing your your cam stuff sometimes the machine  

has a touch plate where it can do it automatically  it can come down and touch something a probe  

and that tells it how long that tool is and other  times it's done at that point when you're creating  

your work offset the last step you're touching it  and it knows that as far away as you are that's  

how long the tool is now remember earlier when  i said sometimes you have to use multiple tools  

that absolutely means that in the middle of your  job you're going to have to take off your old  

tool put in your new tool and tell the machine  how long that tool is for some machines again  

it's a matter of just typing it into an interface  you measure it super accurately you type it in  

for other machines they can come over  and touch off on that probe again  

there's lots of ways but it's important  that you do that because if you don't  

you're going to crash after you've told  it how long your tool is you hit go  

it cuts through it cuts your shape it's beautiful  it's wonderful we love that part cutting is fun

now real quick before i go to the  step after milling i'm going to talk  

real quick about fixturing fixturing is a  specific type of work holding so let's say  

you made your object and you actually wanted to  make 20 of the same object fixturing would be like  

if you made a bracket that held it just perfect  so that you didn't have to go through the entire  

process of setting everything up from scratch  each time fixturing is a type of work holding  

but usually again this is extremely basic  usually fixturing is used so you can repeat  

a process over and over and over and over  without having to come up with fresh cam  

and do your offsets fresh each and  every time you run the job [Music]

your job's done your job is cut now comes  the cleanup you're going to have to take it  

out of the machine and usually a cnc milled piece  is going to have some things that need cleaned up  

sure especially when you get into machining metal  there are some things that you pull it out and  

it's just beautiful and it's done but generally  speaking especially if you're working with wood  

you're gonna have to do a little bit of sanding  to get rid of the marks the tool leaves behind  

or if you're using it for joinery on woodworking  maybe you wanted it to look like traditional  

woodworking so you left the the inside pockets  rounded and you have to go in with the chisel  

and chisel those out a little bit you know  there's lots of little cleaning things to  

do even on metal machines when you're  milling often you're going to want to  

de-burr you know take that edge off of around  things you cut and maybe even throw it into you  

know a sandblasting medium or a vibrating  polisher or something like that generally  

again it's a generalization you're not pulling  completely finished parts off of a cnc machine

so that's it those are the extreme basics of  cnc machines you might be more confused now  

than you were starting out but i hope i answered  some questions about the basics of how they work  

if you're looking to buy a cnc machine you really  need to ask yourself a few questions to help  

narrow down so many of the options what do you  plan on cutting is it wood is it metal what kind  

of metal things like aluminum and brass can be  cut easily on a machine that is intended for wood  

things like steel and titanium not so much if you  wanted to do wooden furniture you wouldn't buy  

a cnc mill meant for metal typically because  they have a smaller work envelope to trade  

off for the extra weight that they have to add  for rigidity so you need to ask yourself what  

you're going to cut how big is it that you're  going to cut and of course what your budget is  

if you are going to be doing predominantly  wood google cnc routers if you're going  

to be doing predominantly metal cnc mills  like i said before there's tons of overlap  

but that will kind of get you pointed in the right  direction thank you for joining me i hope this  

video was at least a little bit useful to some  of you out there who have been curious about cnc  

machines but haven't really dove in to figure  out what it's all about yet be sure to subscribe  

to this channel give us a thumbs up it really  helps us and we'll see you on the next video

you