Machine Tool Buying Guides - TECHSPEX

In the market for new CNC machine tools, there is a wide variety and selection of machines, offered by scores of machine builders from around the world. Vertical machines, horizontals, lathes, gantries, routers, boring mills, screw machines, grinders—the choices are almost limitless.  And there is nothing worse than buying a new machine tool and having it sit in the corner, under-utilized, because it is the wrong machine for the job. Yet, this does happen.So where does one start, how does one decide, and what tools are available to assist a buyer through the process of purchasing a new machine?

US Metal Spinning supply professional and honest service.

Start with Why: The Most Important Question to Ask When Purchasing a New Machine Tool

The first, seemingly simple questions when that must be asked before seeking a new machine tool are all about WHY. Harvard Business School Professor Theodore Levitt famously said: “People don't want to buy a quarter-inch drill. They want a quarter-inch hole.” So, why buy the machine in the first place? What is the buyer trying to accomplish in making this purchase? Before selecting a machine type or specific model, it is necessary to first identify the specific job function or department for which the machine is being purchased. This will give a clear indication as to daily machine usage; lot sizes to be run; and requirements for fixtures and tooling, types of coolant, and tank capacity.

If the machine will be utilized in a job shop environment, the types of parts being machined will be numerous and varied in scope, with lot sizes ranging from one to 50 pieces. Similarly, toolroom or maintenance departments may see a wide variety of machine work but far more limited lot sizes, typically one to five pieces. Machines being purchased for a production environment, however, may be dedicated to machining one specific part or a family of parts. Production lot sizes may range from 100 to 1 million or more parts. Production runs generally have more stringent, dedicated workholding and fixture requirements.

Part-loading considerations are also driven by lot size. Hand loading, pallet shuttles or robot loading are some of the options. Tooling becomes more specific to a production run, whereas a standardized tool assortment works for the job shop. Coolant-tank capacity may need to be increased to handle longer run times for multiple work shifts. Toolrooms and job shops should think about a general-purpose coolant and a flexible delivery system.

Buy With Room to Grow: Consider the Largest Part That Might Be Machined

Once the reason for purchasing the machine has been established, but before machine type or model selection can begin, the technical aspects of the machine come into play, and the most basic but critical questions that must be addressed are: What size are the parts to be machined? Will the machine process tiny parts, large parts or really huge parts? The answer to these questions will help determine the appropriate size and model of machine.

In a job shop environment where parts of a multitude of sizes and shapes will be machined, and where the requirements might change from day to day, the buyer should consider the largest part that might need to be machined. What size parts will the shop be running tomorrow or next week? Future shop capacity also should be considered in selecting the optimum machine size. Perhaps a shop could secure more business if it had a slightly larger machine. It’s easier to step up to a larger model today, allowing for the possibility of bigger or longer parts to be machined tomorrow, rather than purchase a smaller machine and regret that decision six months later.

The weight of the parts to be machined also should be considered as well as the size and weight of the fixtures to be used. Every vertical or horizontal machining center has a maximum allowable weight that can be placed on the table, but there are other machine tool designs in which the machine base has virtually no weight limit.

Let Part Shape Shape Your Choices

Also of utmost importance to selecting the right machine for a particular operation is the geometry and shape of the parts to be machined. Part geometry has everything to do with how the part will be held during the machining process, which will greatly influence the type of holding device or fixtures to be used. Will a simple table chuck do the job, or is a more sophisticated or dedicated fixture, vacuum or hydraulic chuck required? Perhaps the part geometry will require a rotary table for fourth- or fifth-axis machining; and if a rotary table or fixtures are added, the X, Y and Z machine travels must be adequate to hold both the fixtures and the parts combined.

More geometrically complex parts may require a multi-axis machine with full five-axis 3D-machining capabilities, whereby the machine can move in five axes simultaneously, rotating on two additional A and B axes. This enables the cutting tool to approach the part from multiple planes and a variety of directions, reducing the need for multiple operations and additional setups. Part accuracy and repeatability are capabilities that are critical to ensuring the machine’s success.

It’s also important to consider the number of cutting tools required to machine the parts, as well as their length, diameter and weight. The machine’s toolchanger must also have an adequate number of tooling pockets to hold the necessary number of tools.

Need a Meeting of the Minds? Form a Committee to Purchase the Machine Tool

During the machine-buying process, some companies will form committees, especially when numerous departments will be involved in and responsible for the daily operation of the machine. Buying committees allow each department to have input, conveying their requirements and concerns before machine selection.

For example, the engineering department may have concerns about the machine’s ability to achieve and maintain the required part specifications and accuracies. The production department will want to ensure that it will be able to meet agreed-upon production requirements and schedules. The maintenance department will undoubtedly have concerns because its members will be forced to live with a poor machine selection. This department may be most interested in the machine’s spare parts; electrical components; electrical and air requirements; grease, air, and oil filters; type of machine controller; recommended preventive maintenance procedures and their frequency; and general upkeep once installed. Facility representatives might bring up concerns about factory space, machine footprint and layout, electrical and airdrops, and fork truck access. The purchasing department will want to make sure it understands the machine specifications and requirements to apply due pressure on the vendors to achieve the best financial deal and follow-up support for the company.

Machine selection by committee is usually done only in larger companies. Even then, if the machine is being purchased to replace an existing machine, and the required machine type and model are already known, a committee may not be necessary.  In a job shop environment, the owner of the company may be the one purchasing the machine and may find the committee method unnecessary and far too time-consuming. Also, in smaller shops, the owner may be the person operating the machine and knows exactly what he or she wants without needing anyone else’s input.

Do Your Research (You’re In the Right Place!)

Inevitably, all machine buyers get to the point in the process of comparing machine types and machine models. Techspex.com, a free research center and analysis tool, can help anyone find the right machine for the job. This handy website database contains more than 500 machine tool brands with more than 8,600 models of every machine type imaginable—all in one place. Techspex maintains the deepest, most up-to-date machine tool information, whether the equipment is a milling, turning, grinding, EDM or coordinate measuring machine—it’s all here. Simply enter the basic attributes and specifications that are required, and the system will provide a side-by-side comparison by machine type, model and builder. Every search for a new machine should begin with Techspex.

It can be time-consuming to bring in a multitude of machine vendors with varying skill levels, and the varieties of machine products and options that each machine builder offers can be confusing. Techspex can help sort out some of that information.

Comparing CNC machines and wondering which you should buy?

Buying a CNC is quite different from buying a 3D printer, or even a laser cutter.

For a start, there is even disagreement on the definitions for what we are talking about, which we will get into in a second.

Secondly, if you have yet to use a CNC, you might not have a clear idea of what you want to do with it.

Third, there are a lot of variables that we need to consider, that might not become clear until having used a machine for real projects, and that are not apparent even after watching and reading reviews.

Keep in mind also, this is not a CNC review, though I will use my own experience of specific machines to inform my thoughts.

Let’s get into it.

What Even is a CNC?

While most people will have an idea in their head when you say CNC, it simply means it is a fabrication machine under computer control.

That probably serves up more confusion than explaination – with that definition alone, both a 3D Printer or a Laser Cutter are CNC machines.

When we speak about CNC, however, we are usually talking about a CNC Mill or a CNC Router.

Both interpret computer instructions to progressively carve out material using a spinning endmill to create our end-product, and therefore this style of production is called Subtractive Manufacture, versus additive in the case of 3D printing.

Differences Between a CNC Mill and CNC Routers

So there are two types of machine that people really mean when they say CNC, but how are they different?

As you can see in these pictures of machines at Protospace, visually they have a lot in common, but the Mill is set up with a high-torque spindle, and more Z (vertical) + Y (horizontal) travel, whereas the Router is on a moving gantery, and is able to move far further in both the X and Y, with some travel in Z but not anywhere near as much.

Some of the descriptions you hear are applicable to each machine, but if the workpiece moves in all but the up and down (z) direction with the spindle static, it is likely to be a mill.

Mills are more robust, therefore are often used for metal work, or very hard plastics, creating highly precise and repeatable machine parts, for example.

On the other hand, while a router could well cut metal, it would be commonly seen cutting acrylic signs, or in a cabinet maker workshop, cutting and carving MDF drawers and pine doors.

While neither of the above machines would be seen in a home workshop, when we talk about hobbyists, we are almost always talking about a CNC router.

What Do You Need a CNC For?

As we have already seen in the use-cases for a CNC mill versus router, different machines are suited to different tasks.

In determining the specific machine you go for, and the budget you ought to expect, you need to know at the very least:

• What you intend to make.
• The kinds of materials you wish to work with.
• The size of the materials you wish to work with.
• How quickly you need to finish jobs.
• How precise you need your work.

What You Can do With a CNC that 3D Printing and Lasers Can Not

Many people consider CNC routers as being obsolete now that lasers and 3D printing are gaining capabilities, but that is not true yet, and might never be entirely true.

That said, there are many times I consider using a CNC and decide instead to go with 3D printing or laser, just out of comfort and convenience.

Where CNC shines is when you consider materials and scale.

Additional resources:
The Ultimate Buyer's Guide for Purchasing Panel Bending Machine
5 Must-Have Features in a Custom CNC Machined Parts

The company is the world’s best Metal Spinning Machine supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

I have a laser that is powerful enough to engrave metal, and can possibly even cut very thin metal, but on my Nomad 3 I can cut and engrave aluminium well, and make pretty decent circuit boards, including cutting them out.

Even with multiple passes I could not cut anywhere close to the thickness of materials that I can cut on my CNC, and there are materials that would be toxic even if I could.

While CNC is subtractive, just as lasers are, it can do 3D using STL files like 3D printers can. This can be useful for simple things like bevels and chamfers, all the way up to intricate 3D carves.

3D prints are more capable when it comes to shapes, some fine details, and geometry, but CNC is more capable when it comes to size and materials.

CNC Negatives

As mentioned, there are times I turn to my other “digital fabrication” options such as 3D printing and lasers over CNC, and here are some reasons:

• CNC produces dirt and dust. Even with a dust shoe and my enclosed Nomad 3, it is still a consideration.
• They are noisy. I have seen reviews for some more recent machines that are less so, but remember you are using essentially a high powered motor with a drill bit, and using motors to move everything around, and on top of that you have dust collection.
• It’s not just fire it up and go, because you need to hold your work down, you need to change or select the correct bit, you might need to program in new feeds and speeds, and any mistakes means often spoiled material and perhaps a broken bit, or worse.
• They are expensive so you had better be sure your existing machines can not accomplish your objective by thinking in another way. For example, using a 2D laser you can make an assembly or create layers that fit together to make a larger 3D object.
• CNC is a whole new learning curve. Yes, there is a lot of overlap with other types of making, for example you can still use Adobe Illustrator or Fusion360, but that is only a small amount of what you need to know to be productive with CNC.

Considerations for Buying a CNC Machine

Ultimately, the decision between a budget CNC and a fifteen thousand dollar machine depends on your specific needs and goals:

• Determine your intended use for the CNC machine.
• Consider your budget and whether you plan to start as a side hustle or expand into a larger operation.
• Evaluate the level of precision and production rates required for your projects.

Keep in mind that there really is an element of you get what you pay for, but you might be paying for more performance than you need:

• The number one factor in a machine’s performance is rigidity.
• A fifteen thousand dollar machine is built with more substantial materials and components compared to a three thousand dollar machine. Pretty much everything else is upgradable.
• Make sure you don’t over-estimate how large your projects will be. I loved my confusingly-named Longmill (it is actually a router), but I didn’t have space for it so I sold it.

GRBL vs Mach 3 and CNC Software

All of my home CNC machines run on the open source GRBL software. You can be almost certain yours will too, but Mach 3 and other software is out there and highly popular, especially at makerspaces and manufacturing, so we should touch on this.

GRBL runs on Arduino-based CNC controllers and reads GCcode, much like Marlin in the 3D printer world. This means both the firmware and the hardware can be open and free.

Because it is hugely popular, it offers a wide-variety of software options, including UGS, Chili Pepper, Open Build Control, Carbide Motion, Easel, Cool Term, CNCjs, and more.

Mach 3 is proprietary, and $175 at the time of writing, but does have a limited demo license. It uses your desktop computer and communicates via a parallel port. Yes, it only works on a desktop PC with a parallel port, not a laptop.

While not as beginner-friendly, and of course more expensive, Mach 3 does have advantages in terms of capabilities, for example it can control a 6-axis CNC machine. It also supports macros via scripting, which for a regular hobbyist is not a big deal, but for small-batch manufacturing starts to become interesting.

Drive System

The three main drive systems on CNC machines are ball screws, rack and pinion, and belt drives.

It is not true any longer that hobbyist machines will always use belts, but it did used to be the case because belts and stepper motors are cheaper, and are easier to manufacture well.

That said, a premium will be paid for more powerful motors and drivers compared to a less expensive machine.

My X-Carve 500 has belts, but the belts are sufficient for the work it is expected to do. My Nomad 3 is built more like a mill, it has a smaller, enclosed work area, but uses ball screws.

Ball screws are preferable because belts are stretchy and can cause imperfections due to backlash.

One of the things I liked about my Longmill was even though some of it was not super rigid (eg. 3D printed parts), it used threaded rods instead of belts (but not ballscrews unfortunately).

Spindle

Almost every entry-level router will use an off the shelf handheld router as its spindle, or a powerful 24v DC motor. In the former case, the speed will be set manually using the dial on the casing, and will be turned on and off manually too.

A premium built CNC will have a specifically designed spindle that features more power and has programmable speed control.

My CNC Journey

I came to CNC via wanting to prototype circuit boards, because I am scared of nasty chemicals. It was only after owning a machine that I branched out into other things, and eventually took the certification at my makerspace so I could use (and later teach) the big scary Mach3 machines.

This means my machines have almost always been on the smaller size, and my one larger machine as I mentioned earlier, I found I used but didn’t really have space for.

My first machine was pretty bare-bones and has many names, but I knew it as “T8 CNC“. Really, it is just for PCBs, but didn’t do a very good job of that because the accuracy and rigidity isn’t there. What it did do, at a low price, was take away my fear of the machines.

Next was the Sienci Mill One. Sadly, it is no longer produced, but it was a great machine for me. Again, only small, but much more robust and capable. For a teaching situation it especially proved itself, it was bashed around and abused at the other maker space for a long time and survived.

I tested all kinds of materials on that little guy, and eventually outgrew it. First I upgraded to a slightly larger 500mm x 500mm X-Carve, which I still have and enjoy.

Eventually I upgraded in size again to the Longmill. At the time I got it there was a deal where we got an early version at a discount, so I paid under $2,000 CAD for a 30″x30″ machine.

Would it have been nice to just lay down a full sheet of plywood or MDF and get cutting? Sure, but even this machine in our two-car garage had to live hung on a wall.

Many of my friends thought I was losing it when I finally (for now) bought a Nomad 3. This machine has a small work area, and can not even accept larger materials because it is all enclosed.

The thing is, it suits 80% of what I use a CNC for, while keeping all the dirt (MDF and carbon fiber especially) and dangerous flying objects mostly inside. When half an endmill goes ping at high speed, that piece of plastic is an eye-saver.

While we had a workshop I was tempted to get a larger machine again, but now we are space-limited I am glad I didn’t take the plunge. I just wish there was a makerspace nearby as well-equipped as the ones I left behind in Calgary!

Bigger, Better and Newer CNC Options

If you are looking to make stuff for yourself, maybe to sell at craft fairs or Etsy, you do not need to be spending $15,000 on a machine like the Avid etc.

While I am a big fan of open source and community, and especially saving money, if this is your first CNC then I would guide you towards one of the well-known brands with a tried-and-tested new customer onboarding:

• X-Carve: The stripped-down machine costs $1,395, including Makita router. The 4×4 Pro is $5,995 including VFD.
• Shapeoko: The basic Shapeoko 4 starts at $1,800 with a router, and they go up in size and capability from there. The 5 Pro is $3,750 and you can select the basic trim router at +$80 or $750 for the VFD.

Both come with free software and work with the popular third party applications, such as Aspire/Vcarve.

For ease of use, I especially like Inventables Easel, which is browser-based, compatible with pretty much any GRBL-based CNC and is free for the basic license. Optionally there is a pro version.

Another option for CNC brands is Onefinity. I have heard good things about these, and they seem comparitively priced, but I have no personal experience of them.

If those are too rich for your budget, then cutting your budget right down to the level where you won’t be too upset if it doesn’t work out makes sense.

If you want to learn more, please visit our website Metal Spinning Mold.