Category Archives: CNC Info

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.

Manual CNC Programming – Pros & Cons

Manual programming for a CNC mill or lathe has been the most common way to program over the years that CNC machines have been used. Manual programming is done either by hand and transferred to a computer file, or punched in by hand on the machine controller.

Pros

Lets look at the good stuff first… Manual programming is limitless when it comes to developing a part program. You can set and adjust every fine detail to your exact touch, whether it’s tweaking feeds and speeds, changing cycle parameters, or using different cycles.

Another big advantage is that manual programming teaches strong discipline. The machinist writing and/or editing a program must grasp the skill and techniques of CNC programming to be proficient. Every number, every letter, every decimal, must all be to perfection for the program to run smoothly. In addition, being able to do all of your programming gives you an edge over the competition when it comes to looking for a job.

A bonus if you’re going be programming on a CAM/CAD system, is that you will be able to understand what exactly is going on and why. Programming software can get pretty complex these days, and it’s your job to know every little detail on how the part is being programmed.

Cons

Manual programming definitely has its disadvantages. The time it takes to make a complete program is probably the biggest downfall. Compared to making a program/toolpaths on a CAM system, hand writing can take considerably longer, depending on the machinist. Not to mention the time it takes to run the program out and make sure everything works.Manual CNC Programming - Pros & Cons

Another important disadvantage would be the number of errors in the program. When you’re writing a program by hand or punching it in the controller, it’s very easy to make a mistake. All it takes is on wrong number, letter, is a misplaced decimal.

Other areas that make manual programming inferior include: not being able to see your toolpaths, as well as the complication of needing to edit a program and more.

While there are some huge downfalls to manually writing a CNC program, having the ability to manual edit a program is still extremely important in this industry. Just like giving a kid a blow torch; not knowing the basics before using high-tech software is a bad idea.

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 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 – Computer Numeric Control

CNC Stands for Computer Numeric Controlled in the Machining industry. It is the only way to go, as it is the easiest and fastest way to machine parts. Manual machining is virtually extinct in the industry today, and NC is too outdated by today’s competitive standards. CNC is better because you can write and edit programs in the machine’s controller, giving you complete control of how it runs. If part of the program is wrong, just go into edit mode and change a few numbers/codes.

Instead of taking a drill press and drilling out holes in your part, a CNC program can be written to save save if you have many holes or parts, especially if they are close tolerance. Just punch in the drilling cycle code, the coordinates of the holes, and you have yourself a simple drilling program. Of course there’s more to it than that, such as machine and tool set-up, but if you have hundreds or thousands of holes to drill, you’re going to want a CNC machine.