Tag Archives: programming

Bridgeport CNC Conversion – Is It Worth It?

Converting your manual mill (Bridgeport) to CNC is a cheaper way to get into running production runs. While manual mills can still be useful in shops today for certain operations on one-off part, they are virtually obsolete for production runs if you want to make money. However, if you are starting up a small CNC shop of your own or are a hobbyist on a budget, a CNC conversion kit may be your answer. However, lets take a look at what it will take to convert, how much it will cost, and how it compares to a a VMC (vertical milling center).


You can buy a CNC conversion kit and piece it together yourself, or you can buy a mill that has already been converted. Of course buying one that’s all set up and ready to go would be ideal, but you may not have that much cash to spend right away. This is why many machinists end up buying the parts as funds allow.

If you want to convert your Bridgeport (or similar) manual mill to CNC, I suggest doing a full 3-axis conversion. It will be more expensive, but if you are going to do the swap, you might as well go all the way. Being able to program for Z-axis moves in addition to the X and Y-axis will allow for shorter machining times.

Bridgeport CNC Conversion
Bridgeport CNC Conversion

So how much will it cost? A knee-mill (bridgeport) converted to CNC will cost anywhere from 10K-25K. The newer and nicer set-up the more expensive it will be. Shopping around and waiting for deals may help lower that cost, but you should still expect to end up in this margin for a ready-to-go mill.

Buying a VMC

While buying a vertical milling center will be more expensive in most cases, they are much more capable machines. Faster rapid moves, a lot sturdier, more horsepower, coolant, automatic tool changes, and the list can go on. It really depends on how much you want to spend and how big of a machine you want. $20k can get you a used CNC mill, but it will probably be 15+ years old and will need a lot of maintenance sooner rather than later. For another 10-20 grand you can get a newer and nicer machine that will actually last a while depending on how you use it and what kind of deal you get.

What Do I Recommend?

Without a doubt, a VMC is the better choice IF, and that’s a big if, you have enough dough. Of course, many of us that are middle or lower-class citizens cannot just throw $30,000+ at a machine at any given time. This would be a long-term goal, but the capabilities are are vastly greater than a converted knee-mill.

I Should Buy/Build A Converted Manual Mill If I:

  • Am on a budget
  • Have time to convert it as funds/time allow
  • Am just a home hobbyist
  • Want to DIY to save money

I Should Buy A VMC If I:

  • Want a faster, sturdier, more powerful and capable machine
  • Want to make a business out of it
  • Have a bigger budget
  • Have patience to save up for one (If funds don’t currently allow it)

There’s advantages to buying each kind of machine. While I haven’t said which one is better for YOU specifically, I have tried to lay out reasons why you would or wouldn’t want to go a certain route. If you have any questions, feel free to post a comment.

Tool Runout vs. Tool Deflection – What Are The Differences?

There’s a reason tight tolerance parts cost more time. Yes, I use the word “Cost” because time is money, and it can take a considerable more time to set-up and run a part if the tolerances are closed up. Tool run-out and tool deflection can both be an issue when trying to hold a close tolerance. However, they are not the same thing.


Tool run-out is how far off of the rotating axis the tool is. While in the machine, you want to check just above the bottom of the tool, as that will give you the most accurate reading and is almost always worse than the top of the tool where it goes in the holder. To check it, put an indicator on a vice and touch the tool off of it. Zero it out and then rotate the tool (usually in a counter-clockwise rotation so it doesn’t catch the cutting edge). If there’s run-out, one side of the tool will give you a different reading on the indicator.

Before we go any further, let me explain what run-out actually does when machining a part with a tool that has it. If an end mill or a drill has excessive run-out, the side (or flute) that is bigger will do more cutting. If you’re milling out a hole with an end mill, it will cause the hole to go over-size if all of your program and offset numbers are right. A drill can also go oversize, as well as drill an oblong hole.

Now lets take a look at what causes a tool to have run-out. A brand new and unused tool can have run-out. Why? Not all tools are made the same, and if you buy cheap tooling, there’s a better chance that it was made with the same precision as a higher quality tool.

Not only can the tool be at fault, but a defective tool holder can cause run-out as well. On the other hand, you may check the tool while in the spindle and see that their is run-out, but certain tools (such as a reamer or drill) will allow you to slightly move it without removing it. This can often get rid of many run-out problems with longer tools.

Tool Deflection

Tool deflection should not be confused with run-out. It is a common term used when side milling with an end mill, and it causes a taper in the part feature that is being milled.

Take this as an example; you’re milling the outside profile of a part (2x2x2.25″) that has blueprint dimensions of 1.950″ wide, long, and 2.000″ tall. Using a 3/4″ end mill with greater than 2 inches of flute length, you mill around the part once. The top of the part is 1.951 all the way around, but the bottom is upwards of 1.954″. This is because the end mill is too long and was ‘deflecting’ because it couldn’t handle the pressure of removing all of that material.

That’s the most simplistic scenario of tool deflection. So, how do I combat this? Great question, and there’s quite a few ways to make sure your part is square, perpendicular, and/or parallel.

First of all, how deep of a cut are you taking? If you’re drilling a 1/4″ hole that’s .375″ thru, you don’t need a jobber drill with 4″ of flute length. When milling, a bigger diameter tool will be stronger and resist deflection better. If you’re milling a feature that is .400″ deep, using an end mill with 1/2″ flute length will achieve the best results. One last thing on tool length is that you should have the tool as short as possible in the holder. Do not clamp on the flutes, but if you choke up on the tool, this will also help prevent deflection.

Feeds and speeds. I’ve said it before, and I’ll continue to say it. Having the right RPM and feedrate for your tools is one of the major keys to success in the Machining industry. Even if the surface foot is close, having a high feedrate will naturally produce more tool pressure and in turn cause deflection.

Slowing down the feedrate can help, but in the end, you may have to take multiple passes to make a feature square, especially if you’re profiling out a part with an end mill.


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.

CNC Programmer Salary – How Much Am I Worth?

Are you good at programming on CAM/CAD software? Programmers are in high demand in most areas around the United States. The salary, or wage, for CNC programmers depends on a couple things. There’s a wide spectrum of programmers because not everyone has the same experience. However, just because you have 10 years of programming ‘experience’ doesn’t mean you’re worth more than the other guy that gas only 3 years. More on this later…

Master The Systems

While a programmer with less years on the job can get paid more, the more you know the better. Having 8 years of experience on Mastercam is great, but if you know how to program on Gibbs, Surfcam, as well as multi-axis on CAM systems, you’re worth more to certain companies.

Knowing how to run multiple CAM or CAD systems gives you an edge over the competition if you’re looking for a job because you’ll fit the “requirements” for a lot more companies that are looking for a programmer.

CNC Programmer Salary - How Much Am I Worth
Programming on Mastercam

Even if you haven’t worked with a certain software that a company you want to work for uses, having experience with multiple other systems makes you more versatile, which will making it much easier for them to train you in on their programming software. Every CAM/CAD system is different, but you’re essentially doing the same thing with all of them; programming. If you’re used to being acclimated to a new software, learning how to use one more shouldn’t be an issue.

What’s the Demand?

If there’s no demand in your area for a programmer like you, don’t expect to get a high paying job offer in the near future. Big cities with Machining, such as Houston, Minneapolis, and Ohio have a high demand for any and all kinds of Machinists or Programmers. Finding a job in these areas isn’t too difficult today because the manufacturing demand is high.

If you want to get started as a programmer, you can find easier jobs at shops that will start you at the bottom and work your way up if you only have school experience. It’s not going to be a wealthy salary, but it’s better paying than most operators.

Let’s See Some Numbers

Okay, this is probably the real reason why you’re here… Programmers are usually paid more than machine operators, which is a big reason why so many machinists go to school for programming. Before I throw any digits out there, you should know that these are not set in stone. Every market and area of the country/continent is a little bit different. These numbers are a general starting point to show you what a CNC programmer can make for a living.

If you’re looking for a first just as a programmer, even if you’ve been a machinist for a few years, you’ll probably start towards the bottom of the pay scale. Right now, most full-time programmers start out around the 18-20 dollar an hour mark. It won’t make you rich, but if you’re looking for a good starting job, there’s usually a good amount of room for improvement.

If you look in the classifieds of Job listings, you’ll often see Programmer wanted ads with 3-5 years of experience. With more experience, comes more money (for the most part). The compensation is usually in the low-mid 20s for wages, and if you’re working overtime like a lot of shops do these days, that could be a pretty decent paycheck. However, like mentioned before, not only do you have to have the years of experience qualification, but also the right kind of experience as far as programming on CAM/CAD systems.

For you programming masters out there, high 20s and into the $30+/Hr mark is not uncommon. Some machine shops just need a lead programmer that can do it all, and to some companies, that person may be worth 35 bucks an hour.

Lathe and basic mill programmers are usually at the bottom of spectrum because they require the least amount of skill and training. The high-end jobs are usually multi-axis or special milling programmers that require a lot more training.

Once again, these salaries aren’t going to make you a millionaire. But that’s not why you chose CNC Manufacturing as a career, otherwise you would have gone a different and probably less interesting route.

If you have any questions, feel free to post a comment…

Basic Programming Terms – CNC Structure In 4 Steps


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.


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.


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.


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

CNC Programming Training

CNC Programmer Training Requirements

In order to become a CNC programmer, you must have extensive knowledge and experience as a machinist and troubleshooter. Programs are written in G-codes and M-codes, but modern CAM/CAD software has made it easier to perform complex and precise operations. Depending on how quickly you catch on, it can take years to learn how to program parts from start to finish. You must know the ins-and-outs of machining; how machines work, how materials react, what kind of cuts to make, what tools to use and how to use them, how to order the operations, and the list goes on.

Machinists use to mill, cut, drill, and form parts on a manual machine. This resulted in much slower and less-than-consistent parts, depending on who was running the machine. However, being able to machine parts on a manual mill and lathe will greatly help you understand on how to program parts in the future. I also strongly recommend that you learn how to hand write your programs before delving into CAM/CAD software. It will take longer to learn, but being able to edit/fix your program after it is written on software is priceless.

The time of programming training you need depends on the machine shop you’re working in and how complex the parts are. A shop that makes fairly simple parts on 3-axis CNC mills will require much less training than a shop that does 4 or 5+ axis milling.

Most machinists learn on the job over the years from more experienced people and work their way up the ladder.

What Are the Benefits of Becoming a CNC Programmer?CNC Programming Training (2)

There’s several good reasons why you should train and work hard to become a programmer. Yes, it is more demanding with an increase in pressure, but what higher paying jobs aren’t?

The first reason is obvious, as you will be getting paid more than a machine operator. This reason alone is worth the time spent learning and practicing how to program. Learn from the best and you’ll be the best.

Second, it will open up more possibilities in the future if you plan on moving some place else. It’s always good to add things to your resume, and more companies will consider you with programming experience under your belt.

Another reason to train to become a cnc programmer is because you won’t be doing the dirty grunt work. No more cutting stock, deburring parts, or getting filthy from all the oils and dust. Programming is usually done in a separate room or part of the building that is clean with computers.

Where Do I Get CNC Programming Training?

If you are already on the job as a machinist, the best way to learn how to program is by “shadowing” someone that already knows how and is willing to teach you over time. If you have an experienced co-worker that has the ability to do that, take every advantage of that as you can!

That, and taking classes at your local Tech school are going to be the easiest ways to get trained in. If you have the time, it might be worth it to check your local Technical school for CNC Programming courses. There you will get hands-on work, and you will learn new things faster since you will be working on it every day.

Another possible way of learning how to program is with a Programming Training Software. If you are good at learning things on your own, this may be the best route for you, as you can train on your own time. It’s cheaper than going to school, and you can always go back and re-learn things. However, if you are someone that asks a lot of questions and needs a mentor, this may not be for you.

Click Here To Buy My CNC Programming Handbook. I have found this book to be the most resourceful as far as programming goes. Everything you need to know about programming 3-axis parts is in this book.