Tag Archives: cnc machinist

2 vs. 3 Axis Machining – CNC Profiling

Traditional 2-axis milling on a CNC machine is still very common, you adding another axis to the equation greatly expands your possibilities. You can make parts that you might not have been able to before when just using 2-axis programming, and it can possibly reduce cycle times.

First, we must establish the difference between two and three axis machining. Most CNC mills these days should be able to accept and perform programs with 3-axis machining. Two and three axis machines both have an X, Y, and Z axis, but using that third axis for milling profiles can allow you to profile the surface of a part.

In 2-axis milling, you can move in the X and Y-axis at the same time if you’re milling the outside or inside profile of a part. If you’re using the third axis, you can make X and Z-axis moves while milling a profile, such as a waving contour. You can also move in the Y and Z-axis if you simply change the plane that you program in.2 vs. 3 Axis Machining - CNC Profiling

If you’re hand-writing the program, G17, G18, and G19 are the CNC commands for selecting which plane you want to machine on.

G17 is the XY plane.

G18 is the XZ plane.

G19 is the YZ plane.

Other than that, programming is virtually the same as any other G-code program. If you want to make a positive Z and negative Y move, an example would be:

G90 G20 G19 (To set the YZ plane and absolute)

 

G1 Y-.5 Z2.23

If you want to go back to the traditional XY plane, a line with G17 will be needed.

If you have rendering software or a program that simulates your program, I strongly recommend using it on a new program, especially if this full 3-axis machining is new to you. Good luck, and go experiment! The best is experience is with machine time and trying new things.

How To Get Fired/Hired On Your First Week As A Machinist

Starting or transitioning to a new job can be difficult. New people, different machines, new shop, and a different way of doing things (to an extent). If you’re already hired and can actually do what you put on your resume, it’s not very likely that you’ll be fired in the near future. That is, unless, you have the same routine at every job. Allow me to explain…

It is easier to train one guy to work like the other 20 machinists, than to train the 20 to work like one machinist. If you already have a way of doing things as a machinist, be prepared to change it up a little bit. Just because you learned how to do something at your previous job or jobs, if your new company does it a different way, YOU are the one that has to change.

A company is not going to change how they do things just because that is how you learned it. One of the quickest ways to get fired is by disagreeing or trying to force your own techniques onto the new shop. Unless they are very open to new ideas and strategies on how to manufacture their parts, they will only keep you so long.SCCCNC1.JPG

So, how do I keep my job after the first week or even month? By working with them and doing things how they want done. Now this doesn’t mean that every technique has to be the exact same, but the process and finished part should be identical. If you think they are doing something wrong or less than efficient, politely suggest to them how they could improve, and ultimately, save money. If that doesn’t catch their attention, then so be it; either deal with it or move on.

If they have a improper machining practices and aren’t willing to accept any better methods, then maybe it’s not so bad that you find another company to work for. It’s often hard to find out how a company operates during one short interview. You don’t really know how they do things until you start working with them.

Basic Programming Terms – CNC Structure In 4 Steps

Character

The smallest unit in CNC programming is a character. It can be a letter, digit, or a symbol. They are combined to make ‘words’ in the CNC language. A letter is just what it sounds like; a letter from the alphabet. While 26 letters are usable for programming, read this article for a list of commonly used letter codes.

There’s ten digits, 0 to 9, used to make numbers in programs. They are used in two different ways; with or without decimals. It depends on the mode, as well as the control. A number can also be used in place of a decimal-number if the controller allows it.

Symbols are the third type of character used in CNC programming. It depends on the control options, but the symbols used most often include: a decimal point, parenthesis, minus sign, as well as a percentage sign.

Word

Words are the next step in the structure, and they are simply a combination of characters. A word consists of a capital letter, followed by a number, and sometimes a symbol, depending on the code. Words are used to specify speed, feedrate, position, commands, and other functions.

Block

Basic Programming Terms - CNC Structure In 4 Steps

A Block, also known as a Sequence block, is multiple Words. A word is just one piece of information or instruction, while a block uses at least one word to make a complete command or cycle. Blocks are written on separate lines, and are separated by an “End-of-Block” code.

Program

How do you get a CNC Program? You put a bunch of Blocks together that will machine a part. As simple as that sounds, you have to have all the right characters and words to get each command to work. A program will begin with a program number, and will be sequenced by blocks in order of operations, and end with a program stop or cancel code.

Character > Word > Block > Program

Drill, Bore, Ream, Oh Why!?

Drilling, boring, then reaming is the proper order of operation when machining a hole. This is just one of the fundamentals you will learn in Machining 101. Whether you’re on a manual mill or a cnc milling center, this process will get you the most accurate hole size.

Why can’t I just drill? That is a very good question, if you’re just starting out as a machinist or are in training, you probably won’t know how every kind of tool is going to perform. While a drill, even when spot drilled, can make a nice looking hole, it can’t always hole a tight diameter or circularity tolerance. A standard drill can walk, and that can change the location if it’s a thru-hole. Drills are not always ground perfect, resulting in one lip bigger than the other. This causes the hole to be more egg-shaped and often over-sized.

Want a perfectly circular hole? The boring bar comes next because, unlike a drill, it is sturdy and will follow the same path all the way down the hole. A drill is floating in its holder that causes run-out, but a boring bar is sturdy and will make a circular hole, whether the existing hole is already or not.

Boring Bar and Inserts
Boring Bar and Inserts

The reamer comes last if you want an accurate hole. You should only leave several thousandths left after boring, depending on what material you’re cutting. A reamer is much more precise than a drill, but it will follow the path of the existing hole. This is why you should bore the hole prior to reaming, otherwise the ream will follow the path of the drilled hole, which may not be straight. A bore is accurate, but you can get a better finish with a reamer, and it can still hold tenths for a tolerance if you have a good reamer.

CNC Machinist Training Requirements

Before working as a CNC Machinist, most companies require some previous experience or training. It could be getting certified at a Tech school, a certain number of years working with a number of machines and program controllers, or using specially tooling/machinery.

It really depends on the shop and what they’re looking for, but you should decide what kind of shop you’re wanting to work at in the first place so you know what to work towards.

Here’s some general requirements for each stage of a Machinist Career (Each level is a prerequisite for the next level)…

Basic Shop Helper/Student:

  • High School Diploma/Currently enrolled
  • Basic math knowledge
  • Hard worker
  • Punctual
  • Can Pass drug/background check
  • Ability to lift 30+ lbs.
  • Listens to authority
  • Quick learner and motivated

Entry Level Machinist/Operator:

  • 1-2 years of Machine trade school or previous experience
  • Ability to use basic inspection tools such as: caliper, micrometer, thread gauges
  • Be able to set tool/work offsets if needed
  • Can change out parts and properly deburr
  • Operate a band-saw
  • Occasional light assembly
  • Able to interpret blueprints

Mid-level CNC Machinist:

  • 3-5 years of previous machining experience and/or schooling in Machine Trades
  • Ability to do to set-ups on CNC milling machine or CNC Lathe
  • Ability to program and edit programs if needed
  • Some experience with CAD/CAM software preferred (depends on the position)
  • Ability to inspect own parts with proper tools
  • Math/Basic trigonometry skills
  • Basic knowledge of feeds and speeds for materials

Lead Machinist:

  • Good communication/interaction skills
  • Proficient in troubleshooting machine and program problems/alarms
  • 5 or more years of previous experience
  • Ability to teach and train new employees on machine operating, set-ups
  • Certified and experience with fork-lift operation
  • Report all maintenance and important issues to Manager
  • Understand the capabilities and limitations of each machine
  • Be a leader and organized

CNC Programmer/Engineer:

  • 2-5+ years of previous programming experience with CAD/CAM software (Gibbs,Surf,Bob,Mastercam,Solidworks,etc.)
  • Complete understanding of machine usage and programming G & M codes
  • Awareness of cutting tool technology
  • Complete understanding of work-holding strategies
  • Ability to make/utilize work fixtures with simple and complex parts
  • Strong tooling knowledge, as well as optimum feeds and speeds for each job
  • Ability to program for different machines; mill/lathe/4th axis/live tooling (if required)

CNC Machinist Training RequirementsNow not all of these are going to be the exact requirements for the job you’re applying for. However, it is important that you experience and can do all or most of the above in the given category for the job you want.

The more you know, the more your future employer will consider you. Having a strong resume doesn’t always get you the job, but it can help you get the wage/salary that you deserve based on your skill level.

What Is A ‘Billet’ CNC Machined Part?

When you hear the words “Billet Aluminum” or “CNC Billet Machined”, what comes to mind? Usually people think of shiny and intricate parts. They can be ‘bling’ parts for automotive toys, such as snowmobile or ATV parts, or it can be something that is an upgrade from an oem part.

So, what is the difference between billet and… well, not billet? If it’s not a billet part, then it’s probably cast, which can also be machined afterwards. An example of a billet part would be something completely machined from a square piece of stock; no casting or forging involved. Billet does not only mean it’s made out of aluminum, although it is the most commonly known material for it. You can also make a billet steel, copper, stainless, or brass part.

Pros?

There are several advantages to making a billet part, both over cast as well as forged. The biggest advantage of machining is the accuracy and consistency. A CNC Milling center can hold much tighter tolerances than a mold or forging metal into a part. If you need a precise part, such as small gun pieces, CNC billet parts are the way to go.

Billet Aluminum Dirt Bike Engine Case
Billet Aluminum Dirt Bike Engine Case

However, it is depends on the company/machinist that is making the parts. If they are done right, all tolerances will be met, it will look “pretty”, and it can be just as strong, if not stronger, than a cast or forged piece.

Cons?

While it is easier to hold tighter tolerances, machining a billet part takes more time than casting or even forging a part. Once the mold is made, you can make parts in minutes, if not seconds! Set-up time is very costly, and setting up a CNC milling center or turning center can take hours. However, the more parts you run at a time, the more it will offset the set-up cost. That still doesn’t take away the cycle times and cost of tooling.

Compared to forged, it isn’t always as strong because the parts are literally ‘forged’ into place. However, you can take a forged part and machine extra features on it if you have a tight tolerance.

In the end, it comes down to what you need. Each kind of part has their own advantages. Billet pieces look really nice, can be made to hold precise dimensions, and as a result they may function better than a cast or forged piece.

CNC Software For Machining – What Is The Best CAD/CAM System?

If you want to be a programmer or make your own parts some day, you’ll want to get a good software for CNC machining. There are a lot of different systems out there, but you don’t always need the biggest and baddest one if you can make your parts with a cheaper software.

CAD vs. CAM??

First of all, lets answer this question on CAD versus CAM systems. CAD programs are used mainly for making part drawings, blueprints, and make an overall model for the part you are going to machine. CAD is for generating toolpaths for the designed part. This is usually with G-codes and M-codes. Why do I need these, you ask? Well, to be honest, you don’t. You don’t even need any kind of software for machining. That is, unless, you don’t want to write everything by hand.

Lets face it, technology has skyrocketed in the past few decades, and even in the last 5-10 years, efficiency and quality are in high demand. China still can’t compete with USA made stuff, but for everyone to start buying from the United States again, companies want to buy parts and tools at a Chinese price tag. In order to bring the cost down, efficiency is extremely important, and this doesn’t just include programming a part (Read more about this on my Keys To Being A Good Machinist post).

Computer-Aided-Design

In order to be efficient, buying a CAM system may be necessary if you get a lot of blueprints and drawings. You will be able to make part drawings, fixtures, and jigs, which can also help reduce set-up times (the ultimate money maker/loser).

You can draw 3D models of parts to see different views of it, which can help the programmer when making toolpaths for it. With Cad software, you can put pieces together with an Assembly feature. With this, you can see what it looks like when the part is in the fixture you also designed. You’ll be able to determine what tools to use and how to optimize the set-up before you even start cutting metal.

There’s a lot of CAD systems out there for CNC machining, but if you’re running a real machine shop and need to be competitive, you’ll have to shell out some dough to get one. Free software will not get you very far, which is why it’s free. However, you may be able to get a free trial for paid software, which I recommend if you have the time. The most popular CAD systems include: Solidworks, AutoDesk Inventor, BobCAD,

Computer-Aided-Manufacturing

When used together, Cam and Cad software can be a powerful combo because they save time, which relates to money. If you have to hog out a billet part, writing out a program on the machine or by hand can take hours, and sometimes days if the part is large and/or complex. While I believe that you should be able to hand-write CNC programs first, CAM software can make almost any part in a fraction of time.

In the system itself, once you have the part model loaded, you don’t even have to write any kind of code; the computer does it for you! Let me explain… Lets say you have a 2 x 2″ square part that you want to mill down to a height of 1.5″. In the CAD program, you set the stock size and where the offsets will be (X, Y, Z zero). Once you have that, you pick the tool you want to use (we’ll just pick a 3″ face mill for this operation). Then you pick what kind of toolpath you want it to run; there’s a lot of options for this, but we’re just milling off the top. After that, it’s just setting your parameters for where you want the tool to start and end, how much material to take off, how much you want to take off each pass, and what you want it to do after the operation.

There are so many things you can do with a modern day CAM system that it can be rather intimidating to someone that hasn’t used one before. If you get a training book or have an experienced programmer teach you, starting out will make things a lot easier. The more time you get on the software, the more you’ll figure out what you can do with it, which will help reduce operation times, as well as being able to make more complex parts.

Mastercam is one of the most popular CAM systems because it is easy to use and is fairly versatile. Surfcam, BobCAD, EdgeCam, and RhinoCAM are also great software for machining. It also depends on what you’re machining as well. Are you just doing 2-axis milling? 5 axis? Turning on a lathe? Live tooling? Doing a little research will help you find out the advantages of each CNC software system.

When it comes down to it, it really depends on how comfortable and experienced you are at using a CAD/CAM system, as well as how complex your parts are going to be. If you’re just using a 2-3 axis vertical milling center or a CNC lathe, you will more than likely be able to do everything you want on them with a more inexpensive software. Finding one that is easy to use should be high on the list if you’re just starting out. However, this can be a compromise that will hold you back when you want to do more technical operations.

 

What Is The Key To Being A Good Machinist?

Do you want to be a “Button Pusher” for the rest of your life?? Some people don’t have any motivation in life, so they continue doing the same old job in a machine shop for years, or possibly decades. But, if you’re like me, you want to keep moving up in the industry. To do that you have to have some natural ability, but more importantly, you have to be willing to work hard and learn from wiser machinists.

Starting out at the very bottom (yes, I mean sweeping the floor of your local machine shop) is where some of the best machinists alive today started when they were in high school. If you’re a good worker and your boss sees that you have some potential, you will get promoted. Trust me. It may take several months, or even a couple years, but eventually you’ll work your way to running and setting up machines if you have the desire.

Feeds and Speeds

If you want to be an independent CNC machinist, you HAVE TO know your feeds and speeds. In a production shop, most of their money is made by perfecting the speeds and feeds of each individual job. If you can save a few minutes here and there, or even seconds, it all adds up, especially if you are making hundreds of thousands of the same parts. Time is money in a machine shop, and if you aren’t efficient, you aren’t making money.

Which leads us to our next topic…

Fixture and Tooling

Making a part/programming is usually the easy part. Making a fixture and selecting the right tooling that will make the job run as efficient as possible is not always easy. Some jobs require special jigs, fixtures, clamps, or something exotic to hold the parts. The tighter the tolerances, the better the fixture has to be made.

The difference between using cheap tooling that works and the right tooling that is more expensive but performs better will be huge. In a job shop every minute counts, so if buying an end mill that costs twice as much as normal will last ten times as long and allow you to cut faster, it could mean the difference between making money and losing money.

Knowing what type of end mill, drill, or tap for a 303-stainless part will come with time and experience. Not only do you have to have the right tool for the job, but starting with the correct surface foot is key. Once you get a job set-up that is running 100% with no problems, then you can start optimizing the feeds and speeds.

Problem Solver

Can you come up to a problem with little to no knowledge of what was done by the previous person and fix it within a reasonable time? Machining requires problem solving almost every day, whether the previous person on the machine messed up a set-up and left a mess for you, or you’re programming a new part and the tool keeps breaking. Like everything else, with more experience, you will be able to solve more problems. Eventually you will come up to a problem that you’ve seen more than once before and know exactly what to do.

Be Teachable

Are you hard to get along with and known as a “know-it-all”? Sorry about your luck, but you probably won’t get very far in this industry with that mindset. Machine shops run the best when everyone helps each other out. No matter what you think, there will almost always be someone that knows more than you. So if they try and correct you on something you’re doing wrong, pay attention and thank them. Watch how they do things and try to learn as much as possible from them. This will help in the long run for everyone, and especially yourself if you want to move up in this industry, which will ultimately lead to higher wages.

This Is An Underpaid Profession

For what you have to know, many CNC Machinist positions are not paid enough. Before I go any further, I want to point out that anyone can make a living as a machinist if he/she puts forth the effort, especially with overtime hours. If I were to go over all the details of what all you have to know to be a true CNC Machinist that can virtually run a shop, it would be the size of a novel, and I don’t have time for that right now.

After you get your feet wet in a shop after getting some machinist experience, you’ll quickly realize what it takes to be able to make a part from start to finish. And if there’s any problems on the way, a machinist has to know how to solve it quickly to be able to make positive cash-flow.

CNC Machine Shop – What Is In It?

While every machine shop is different, you’ll see similar set-ups when you walk through them. There will usually be the main area where all of the CNC milling or turning centers are, as well as a section to deburr parts. Sometimes there will be deburring tools/machines next to the machine you’re running if the operator does all of the deburring.

Usually in a different area there will be a stock room with all of the raw materials needed for upcoming jobs. These few rooms or areas make up a CNC Machine Shop, which is usually a large industrial or steel building, as well as a small pole barn or garage, depending on how big the company is.

Stock Room

Round stock, square stock, and tubing are the most common, and they are usually 8 or 12 foot bars in length. There should also be a band saw in this same room so that someone can cut up the right size stock for each job. Most shops have an automatic horizontal band-saws so that they can cut a large quantity of parts in a short period of time with relatively close tolerances.

Machines

Machine Shop
Machine Shop

Depending on what kind of a machine shop you’re in, there’s a lot of milling machines that could be running. While milling and turning centers are the most common, there’s many more machines, as well as different variations of each.

A shop can have vertical or horizontal milling centers, depending on how complex their parts on, and if they’re a job shop or a production shop. Vertical mills are the most common because they’re cheaper and easier to use and set up.

Lathes are pretty similar, but they can be a flat-bed, slant-bed, multi-axis, or have live tooling for special jobs.

Other machines include, but not limited to: Wire EDM, waterjet, press brake, turret punch, CNC laser, as well as miscellaneous deburring machines (tumbler, straightliner, grinders).

Deburring

Like mentioned above, there will be some deburring tools/machines if the company wants to save money by doing all or most of it themselves. Often times there will be a drill press and grinder next to each mill so the operator can do most of the deburring right there in between cycle times.

The higher quality and quantity the parts, the bigger and better the deburring equipment will be. Giant tumblers/vibratory tubs are often used in large production shops for basic deburring. Media blasting is also common for parts if they are to be plated or coating with something. Zinc, chromate, anodizing, hardcoat/powdercoat, and nickel are just a few coatings that are done to machined parts to give them a better look, last longer, and/or function different.

Inspection Room

Clean Inspection Room
Clean Inspection Room

The inspection room should be separate and enclosed from the shop. If parts have close tolerances, there will be expensive inspection equipment, and the room will be temperature controlled so all of the readings are accurate and consistent.

Tools will include: a granite surface plate, height gage, CMM, bore gage, go/no-go gages for specific jobs, optical comparator, profilometer, thread gages, and gage pins. Not every job will have all of these tools, but some will have more.

Depending on how big the shop is, you (the Machinist), may or may not be inspecting your own parts. The more machines and tools you learn how to use, the better off you will be, so try to get in on how to use the equipment if there is an inspector at your shop.

Well, that’s the jist of what a CNC Shop has on the inside of it! Check out my other articles for tips on becoming a CNC Machinist. Stay tuned for more…

Machinist Square – What Shape Are Your Parts?

If you’re a new or home machinist, learning how to “square your parts” is one of the first things you should learn. There’s quite a few common tools that a machinist should have in their toolbox, and a Machinist Square is one of them.

Learning how to machine a part on a manual milling machine should be one of the first things in school. Eventually you will need to make parts with tighter tolerances, and flatness/perpendicularity are a big part of it. If your parts are trapezoidal because of tool deflection, I can guarantee that your parts will be rejected.

Machinist Square Set
Machinist Square Set

A good machinist square should be perpendicular/flat within .0002″ tolerance, and should be periodically calibrated so that it stays within spec. However, some squares have a different rating that depends on how accurate they are. A & B are the most common, with B being for the average consumer that doesn’t need extremely close tolerance parts.

A is the higher grade, and while it will cost more, it is what you will want for machining. Don’t skimp out and get the cheapest one you can find. You get what you pay for, and in CNC manufacturing these days, you want every advantage possible.

If you drop it and can see a dent or bend in it, it’s worthless. That’s why it’s critical that you take care of not only a machinist square, but all of your machining tools.

Click Here To Buy My Machinist Square!