CNC Basics - Everything a Beginner Needs To Know
Summary
TLDRThis 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
🔧 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.
⚙️ 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.
🖊️ 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.
📐 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.
Mindmap
Keywords
💡CNC Machine
💡CNC Mill
💡CNC Router
💡Spindle
💡End Mill
💡Feeds and Speeds
💡CAM (Computer-Aided Manufacturing)
💡Work Holding
💡Offsets
💡Fixturing
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
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