Before buying a CNC Router, it’s important that you do your homework. Once you understand the most common terms related to this device, you will be able to understand how they can work for you.
Below are some of the most common terms used:
- Motor – the servo, stepper, closed loop stepper drives provide the motion. The motors come in many sizes and are designated as a NEMA XX size. NEMA 23 and 34.
- Torque – the motor torque is rated in ounce inches, like foot pounds on car engines, only smaller units for smaller motors. The higher the “oz in” the more power the motor has. Rack and pinion, ballscrew, gearbox, belt drive all convert rotary motion into linear motion.
- Spindle – spins the bit that cuts your material.
- Materials – welded steel, bolted steel, solid aluminum and aluminum extrusion provide the framework for the machine.
- Rollers and rails – rollers, round linear rails, and profiled linear rails all provide the smooth motion surface that high quality CNC cutting requires.
- Software – this provides the motion control. There are “branded” proprietary versions that are made to operate specific makes of machine. Other software solutions can operate multiple brands. Some require a hardware purchase, while others do not. Some run industry standard Gcode. Some software is easier to use than others. A good software solution is stable and does not create problems for users, whether you are a CNC router novice or a veteran.
- Connectability – new computers no longer have parallel ports. USB is much simpler to find cables and ports for, but do have low data limits. USB can be problematic as the Windows operation system seems to not care that there is a CNC connection, especially when it is time to “check on” the ink in a printer or other USB device.
The best systems include hardware that allows dedicating computer resources to CNC control. The most popular systems are those that are less expensive and can also be the most problematic. Bear in mind, the difference between the least and most expensive is not as costly as one day of machine time.
CNC Sales Considerations
In the last decade small CNC sales have become very competitive. Each CNC company wants an edge to increase sales. There are many companies that “spin” or “hype” normal specs into something that sounds above normal. Most of the companies have different features, in construction or simply because they purchase different parts than other companies.
To gain sales these different features are describes as “unique” or something akin to “magic”, as compared to the competition. There is no magic. The transformation from “what we sell” into “magic you will buy” is purely marketing hype. The fact is, in today’s competitive global marketplace, if you pay less for one machine than another, you simply receive less; less in quantity, or less in quality.
Before you buy a CNC router, prioritize the following decisions:
CNC Drive System
CNC router machines have three main drive systems – rack and pinion, leadscrew, and ballscrew. Rack and pinion systems are ideal when working with axes over 4ft. long, while ballscrew systems are best reserved for vertical CNC machine axis.
Stepper vs. Servo Motors
The basic difference between a stepper and a servo-based system is the type of motor and how it is controlled. In a servo-based system, there is constant signal feedback from the encoder (or motor) to the servo drive. This feedback tells the servo drive exactly where it is within its move. Thus, the servo drive can adjust its power output, as needed, to complete the move. The servo is much more powerful, has quicker acceleration time and quicker positioning speed.
A stepper based system runs on an open loop meaning it sends out the number of pulses to the proper axis to get to the programmed location. Because of their simplicity, steppers are less expensive than servos and are the most affordable solution to producing CNC motion. They have the limitation that, if overpowered, they can lose synchronization with the computer controlling their motion.
Pay Attention to the Catchphrases
As you look at online brochures or talk to a company’s sales person, find out if that company has something legitimate to promote or if they have something different. Some use outright sleight of hand by directing you in one direction so that you won’t look in another. Also beware of the industry “buzz words”.
Anytime a successful marketing campaign from one manufacturer uses a “buzz word”, their competitors will try to find a way to include that word or phrase in their respective advertising. Pay attention to what salespeople don’t say. Watch out for specs that are published for one model and not another. Find out what is not included with a product and what it will cost to add it.
At CAMaster, we use machinery, hardware and software to facilitate and increase your company’s productivity and efficiency. Our team has a vast knowledge base and we are committed to sharing our experience with you to help you take your enterprise to the next level.
Don’t buy a CNC machine blindly — get in touch with our team for professional advice or request a quote on the CNC machine you’re interested in.