Category Archives: CNC Machines

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).

Conversion?

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.

Mini Desktop CNC Mill – Pros & Cons

CNC mills have progressed so far these days that you can have your own milling machine that can sit on desk or benchtop; hence the name ‘desktop cnc mill’. Depending on how much you want to spend, you could have a set-up for the price of a new computer.

If you are willing to dedicate a good amount of time to learn how to program and use software, having a desktop cnc machine can be a great asset, whether you’re looking to make your own parts/tools as a hobby, or actually turn it into a small business.

So, lets look at the what makes a benchtop CNC Mill an advantage over a full size machine, as well as how they are at a disadvantage…

Pros

Cost

Compared to the price of a new 100,000 dollar milling machine, you can get a mini CNC mill for a small fraction of that. How much do they actually cost? I can’t really give you a good estimate because there’s so many options available. You could buy a basic kit that’s complete for less than a thousand bucks, or you could be a bigger and better machine that’s fully enclosed with more bells and whistles for a few grand.

Fully Enclosed Desktop CNC Mill
Fully Enclosed Desktop CNC Mill

Technology

For the price of a desktop mill, you get a lot of technology, especially if the package comes with a good CAM/CAD software. In the past, you’d have to buy a big manual mill or lathe and convert to a 240 set-up for electricity in the garage/shop. They are not enclosed, so after machining a part you’ll have a big mess to clean up, whereas a desktop CNC can be enclosed so you have little to no cleanup afterwards.

Size

A big advantage of a desktop mill is how small they are, hence the name “desktop” or “benchtop CNC”. Instead of requiring a large garage or pole building to set up a milling center, you can put one of these in your house!

Cons

A desktop CNC mill may be able to machine parts just like a full-size milling center, but there are some pretty big disadvantages. This may or may not affect you, though, depending how what kind of machining work you plan on doing.

Mini Desktop CNC Mill
Mini Desktop CNC Mill

Size

The size of these machines can be a good thing, but it can also be a downside depending on how large the parts are that you are going to make. If you want to make motorcycle rims, a desktop machine just isn’t going to cut it. Not only is the machine itself too small, but you may run into rigidity/machine capabilities if you are removing large quantities of material, which brings us to its next downfall…

Capability Woes

Unfortunately you won’t be able to hog out stainless or hard still parts on most of these mini mills due to the fact that they are not nearly as rigid as a full size machining center. A lot of them are only built to machine plastics, wood, and soft metals such as aluminum. If the metal is too hard, it will cause a lot of spindle/tool vibration, causing poor finishes. It may also end up breaking your tools because the machine cannot handle the extra tool pressure.

3D Printable Objects – Printers For Home Hobbyists

Here at CNCMachinistTraining.com, we want to educate you on everything CNC manufacturing related, and that’s why I’m taking the time to explain what a 3D printer is, and why they are making people thousands of dollars while doing it right in their home.

First of all, what exactly is a 3D printer, and what does it do? Another name for these printers is a rapid-prototype machine, because it can make you a one-off part without having to ‘cut’ or machine any materials.

That’s right, it actually ‘prints’ out a a real part that you can hold and use, as opposed to my typical 2D printer that prints out flat pieces of paper… Want to make action figures, model cars, tools, or a special replacement part that you can’t buy in any stores?! These machines really are amazing, and everyone that finds out about them are in awe of what they can do.

3D Printer
3D Printer

Depending on how sophisticated the printer is, you can take and scan a P-51 Mustang scale model airplane, transfer it to the computer program, pick your colors, and then click print. It will come out just like your existing plane, with moving parts and all!

If you’ve ever seen those older movies where they punch in their request onto a microwave-like machine, and out comes their order in seconds, a 3D printer is very similar, albeit the cycle time is a little longer.

While pretty much all of the personal or hobby printers are restricted to mostly plastics or composites, there are machines out there that can print out real metals, also known as additive manufacturing, but that’s for another article…

Used CNC Milling Machines – What To Look For

Looking to start your own little shop with a CNC milling machine? They can be used to make extravagant parts and turn huge profits if operated by an experienced CNC Machinist. However, if you don’t know what to look for or have proper training, a machine can turn into a very expensive paper weight in your garage.

If you know what you are doing on a CNC machine and are serious about starting a small shop, lets take a look at some things that you should be on the lookout for when buying a used machine. You don’t want to spend thousands on a milling center only to have it need thousands more in maintenance done…

Age

Obviously, the newer the machine the better, as an older one will inevitably cost you more money due to higher maintenance. How efficient do you want to be, and how big is your competition? If speed is not very important, a CNC mill that is 10-15 years old will get the job done, assuming it is in good shape.

SizeOLYMPUS DIGITAL CAMERA

How big of a machine do you need? How big are your parts going to be? Do you have room in your garage/shop? Remember that you have to not only include the machine dimensions, but an additional amount of space around it as well. A common machine will have 40 inches of travel on the X-axis, and 15-20 on the Y-axis. Don’t need something that big? There’s some that are 30 inches, and the mini/tool-room mills have 15-20 inches in both directions. Price coincides with size, so if you are on a budget, get the smallest one possible. This will also allow you to find one that’s a little newer, due to it costing less than a bigger machine.

# of Tools

How big of a tool changer do you need? 10? 20? 40? ATC’s (automatic tool changer) come in a variety of sizes and locations. Smaller carousels that have 10 or 20 pockets are often inside the machines enclosure. If you need one with more pockets or on the outside of the machine, it’s going to cost a little more.

Spindle Hours

The number of running hours on the spindle is an important factor to consider when looking at a used CNC milling center for sale. Machine on time isn’t as important because the spindle won’t be running or feeding. The seller must be able to show you how many hours it has. If they don’t, they’re probably trying to hide something, so it’s best to steer clear from that machine. Under 4000 hours is a good start.

Options

Although options may not add a lot to the value, it may be harder to find the exact machine you want. Some of the popular options on CNC mills are: chip auger, rigid tapping, tool setter/probe, high-speed machining, high-speed spindle, larger coolant tank, coolant-through spindle lines, 4th axis, faster rapid movements.

It all depends on what you need the machine to do, and how patient you are in finding the right machine. The longer you wait, the more deals will show up.

Controller

Are you accustomed to a certain machine controller? If you need a specific brand/model, that will either cost more, or will take longer to find. Fanuc and Yasnac, Fadal, and Mitsubishi are common CNC controls. While they are able to do a lot of the same things, navigation and codes can be quite a bit different. If you’re not sure which one you want, doing plenty of research before will save a lot of time and hassle in the long run when you actually buy a machine.

Noises

It is important for you to go and look at the machine prior to purchasing it. If it is out of state, find a professional or someone you trust to look at it. The seller may be hiding something that can only be  noticed when the machine is running.

Run the spindle and various speeds and listen for any noises/humming sounds. Machines with multiple gears may not make any weird sounds at high RPM, but will at a lower RPM in low gear.

The best way to test a machine is to run a part on it. Have it do rapid moves in all directions and listen for any sounds in the head and ways. Have them do other cycles, such as tapping, drilling, and some hard cuts with an end mill. These tests will give you a good idea if anything needs to be replaced right away.

Shipping

Last, but not least, do you have a way to transport or ship the machine you want to buy? CNC Milling machines are very large, and can cost a lot to ship to your house/shop if they’re out of state. Do so research and find a good company that will ship it without breaking the bank.

To get an idea of how much a machine will cost, check out some listings on eBay. That will give you a better idea on what size, age, and powerful of a milling machine you can afford.