Tag Archives: cnc machinist training

Absolute Vs. Incremental – CNC Programming

To be able to write and edit programs, you must know when and how to use Absolute and Incremental modes effectively. More programs are in absolute, but there are times when it’s easier to use incremental.

There are major differences between to the two, so if you don’t know how each one works, don’t start programming until you read this. Mixing the two up can and will cause a disaster

What Is Absolute?

When programming in absolute, all of your coordinates and movement values will come from the origin (0,0) point. If you want to be in Absolute, the G-code that defines this is G90, which is a modal code.

Absolute Programming
Absolute Dimensioning

Most CNC programs are written in absolute because it is easier to understand. Why is it easier, you ask? Because if you have a lot of coordinates to move, you always know where the center of the tool is in relation to the work offset.

What Is Incremental?

How is Incremental different from Absolute? Well, instead of all of your coordinates/numbers coming from one location (0,0 offset), each move is the distance from your current location. That means if you want 2 holes that are 4.000″ apart and start 4.000″ from your start location, you would use X4.0 twice, as opposed to using X4.0 and then X8.0 for the second hole if you were to use Absolute. G91 is the G-code that puts you in Incremental mode, and it is modal as well.

Incremental Programming
Incremental Dimensioning

Which one is better? That depends on what you’re doing, but 99% of the time Absolute programming will be easier. If you’re hand-programming, it may require a little more math, depending on how the blueprint is laid out, but it will be much easier to go back and read or edit the program if there is a mistake.

In G90 (absolute), no matter where your tool is, you can always go move to a certain location by inputting those coordinates, such as X1.625Y-.875. However, if you’re in G91, you can’t just punch those numbers in if your tool is somewhere other than the origin. If you put in those coordinates, your tool will move a positive 1.625 in the X direction, and a negative .875 in the Y direction from where it currently is.

So, how do you get to that location in G91? You have to know where you tool is, then add or subtract the distance of the location from where it is relative to the origin. You see now why incremental can be very confusing? If you’re in G91 and have dozens, or even hundreds of moves, one mistake in the middle of the program and all of the following numbers will be skewed because they all come from the previous location.

On the flip side, you can alternate between G90 and G91. If it’s easier to use incremental for a few moves, use G91, then when you want to go back to absolute, just put a G90 on the line of the next move.

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.

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 Machinist Job Description

There are many things a machinist may do on a job, and it mainly depends on what kind of shop you are in. For the most part you will be:

Setting up a CNC machine, loading/making the part program, setting up or making fixtures, loading and running parts, deburring and inspecting parts to make sure they’re within tolerance.

While that is the general type of work you will be doing, the list is really endless. You must be able to problem solve, and sometimes the only time you can get something to work is if you have done it before. Experience is one of the most important traits to a good machinist. They will know what to do and when to do it.

What You Must Know Before CNC Machinist Training

CNC Machinist Job DescriptionCNC machining is not for everyone, as it requires many mechanical skills. You must be good with your hands, and be able to quickly learn things. Being able to problem solve on a daily basis is a must. You will be running machines that cost anywhere from 20k, to half a million dollars, and sometimes more. With these machines, it only takes a blink of an eye to make a mistake; a mistake that could cost the company thousands.

Not only are the machines expensive, but some parts that have multiple operations can cost thousands in labor time as well. Unfortunately, even the best of us mess up at times; we’re only human. The more you pay attention to everything you’re doing, and the more experience you have, the less mistakes you’ll make.

A Machinist must be able to inspect his/her own parts to check whether they are in tolerance or not. If not, they need to determine whether a tool offset, work offset, or other variable needs to be changed. The more experience you have, the more you’ll be able to do on your own, which generally means higher pay. You must be able to read and write in legible English, and pass any drug/screening tests that the company or temp-agency has you do. Reading a blueprint, and knowing how to use basic tools such as: micrometer, caliper, gages, and basic drill charts are a must.

Since CNC Programming has become so popular, it’s important that you have some computer skills,  and being able to use CAD/CAM software is a major plus if there are openings for a programmer in the future (if that’s where you want to be at). Programmers get paid more for their ability to make part programs on 3D programming software, as opposed to the Machinists that are on the shop floor. The Machinists must be able to communicate with the programmers and/or engineers to ensure the design and processes will work, or be able to fix them if not.

Last, but not least, a CNC machinist will maintain a safe working environment by knowing how machines work, and what not do to in certain situations. Safety is very important in manufacturing, as it is very easy for things to go wrong, and it happens fast.

The more you know, the more possibilities you will have available. A machinist will continue to update their job knowledge by going to new classes, and being taught by more experienced machinists, thus providing more production to the company.

CNC Machinist Training – How to Become A Machinist

CNC machining and other manufacturing jobs are in high demand in this country (U.S.), although it’s not like it used to be 30 years ago. Back then you could be an intern as journeyman and get paid a small amount while learning all the tricks of the trade. Once you were done, you more than likely had a full time job. Unfortunately, it’s not like that anymore, as many shops don’t have the time to train-in machinists.

While there are many ‘machine operator‘ positions available, most the actual Machinists positions that companies are looking for require you to have 5+ years of experience. This is done to try and “weed out” the rookies that don’t know much about the trade. Like anything else, though, you aren’t going to get rid of a lot of the newbies, and shops may even miss a “diamond in the rough” by having those requirements. I know of guys that have been in the machining industry for almost 20 years that could be out-knowledge by a 1st year semester student.

In order to get experience, you often have to start out at the bottom. There’s nothing like getting on the job experience, but you will want to get in a job that has a positive atmosphere that does things the right way, and have employees that are willing to go out of their way to help a new guy learn about machining. There’s a few different ways to get the experience needed to move up in this trade, so we’ll quickly go over them.

Tech School

Going to a Tech school for CNC machinist training is probably the number one route today. Some shops require that you have a CNC machinist diploma in order to apply. This isn’t always the case, but if you have a local technical/vocational school with a good machine trades program and are willing to go to school for it, that is probably the best choice. I went to my local Tech school for CNC machining, not knowing much of anything about it when going in, and after two years I felt like I learned so much. That’s not going to say you are going to be a lead machinist/programmer after two years of schooling, because there is just so much to learn being a machinist, and you won’t learn nearly as much until you get out on the job.

Intern

Finding an internship may be a bit harder these days, but with the increasing demand for machinists, you just may find one. It may not be a good paying job, but would be great for a younger person in high school. You will learn a lot on the job, and by the you’re done you may have a full-time job there if they like what they see. Just keep your eyes open and something may pop up near you.

Shop Helper/Deburring Parts

Unfortunately, this route is another one that probably isn’t likely for someone that has more than themselves to take care for. If you don’t have any machining experience, you can sometimes find a position at a local machine shop as a shop helper. You will probably have to de-burr parts, cut stock, and other miscellaneous chores around the shop until they feel comfortable putting you on a cnc machine. The pay won’t be the greatest, but it’s hands-on work, and you won’t have to flip any burgers. if you work hard and a manager/shop foreman likes what they see, you may end up being promoted to a higher paying position.

Those are the three most common options for becoming a machinist. The younger you are, the biggest head start you will have, as you won’t have any dependents to worry about other than yourself as far as money goes.

Be professional, work hard, try to learn as much as you can from older and more knowledgeable machinists, and you will get noticed. Experienced machinists are getting harder to find these days, so if you have the desire, I encourage you to work hard at it.

CNC Machine Operator Training

A CNC Machine Operator is someone that runs production parts in a machine shop. They load and sort parts on a CNC machine, whether it be a milling center, turning center, or other computer-controlled machine.

There are many jobs available for cnc operators because schooling is not necessarily required. A machine operator can get trained in by the CNC Machinist or shop foreman on how to do the required tasks. Any school that has a Machine manufacturing program will teach you how to run machines, make and inspect parts, and how to do well in the industry.

CNC Machinist Jobs

CNC Machinist Jobs are in demand. Manufacturing is starting to pick up again here in the States. Don’t miss out, as there are already job openings, and many more to come, as the “baby boomers” will soon be retiring… Check your local classifieds and listings for jobs in your area. Currently, the Houston, Minneapolis, and Ohio areas in the the highest demand for CNC Machinists.

For local jobs, check out our page, “Job Listings“.

CNC Machinist

Are you looking to become a CNC Machinist? This video shows you some of the many things you could be doing as a machinist. Machining requires a lot of different skills, but with training and/or schooling, finding a job in this career isn’t as hard as most, due to the high demand. Machining often involves: hands-on and physical work, math, problem-solving, program editing, and setting up machines.

Initially, CNC machining jobs are usually well paying jobs if you’re just getting out of school. However, as a career, CNC machinists are often underpaid for what knowledge they have to have. It’s not something you’re going to get rich with if you’re employed by someone, but it will definitely pay the bills, especially if you’re working long hours. There are a few different job positions at a machine shop: a machine operator, a machinist, and a programmer.

machine operator is paid the least because the least amount of experience is required. Operators are often called “button pushers”, due to the fact that they don’t do much more than load parts in the machine. If any real problem occurs, they have to call on the “Machinist”.

A Machinist is someone that has been trained and been around the job for a while. They are very good at problem solving, whether there’s something wrong with the machine, tooling, part set-up, or program. They can set-up jobs, make fixtures, know how to adjust feeds and speeds of machine for maximum efficiency, and edit programs when needed.

A Machinist may move up to the “Programming” position if the manager deems them qualified. They are paid more because they are required to program the tool-paths for the parts. They get a blueprint from the engineers and have to know which operations are required and when. They have to account for many variables, such as fixtures that could get in the way, vice jaws, machine capabilities, and many more.

Do not be intimidated, as many other careers are difficult like this. If you have the motivation, and these descriptions peak your interest, the manufacturing industry in the U.S. could use your help.