Entry-level CNC machines come in different classes and capabilities. But how do you choose the right one for your shop?
At some point, just about every custom woodworker will consider making the switch over to CNC. But with so many options, where does one begin? To help custom woodworkers make an informed decision, CWB spoke with several entry-level CNC manufacturers for tips.
Q. What can a shop buying an entry-level CNC machine expect in terms of performance capabilities and maintenance requirements?
A. Chris Burns, vice president, ShopBot Tools Inc.: Entry-level machines have come a long way since the turn of the century. You can now purchase a CNC for $6,000 to $15,000 that is a true industrial workhorse capable of multiple shift (seven to 14 hours per day) operation without worrying about speed, accuracy or durability.
Machines in this price range can vary in cutting area from 2 feet by 4 feet to 5 feet by 10 feet, with a 6-inch Z-axis. A tool in full production will change out consumables, such as pinion gears (on a rack-and-pinion drive system), every six to 12 months at a cost of around $100. Other maintenance includes light greasing of the racks and maintaining a flat spoil board by surfacing and replacing when necessary.
A. Norm Frampton, director of marketing and communications, General Intl: We’re offering two sizes of what would be considered our entry-level units. One model is a benchtop unit that can handle a maximum workpiece size of 20 inches by 20 inches by 2 inches. The other model can handle a maximum workpiece size of 20 inches by 36 inches by 2 inches. These entry-level models feature a high-duty rating and are suitable for small to medium-sized shops. They are made for up to six to eight hours of use per day, in contrast to models designed more for light to intermittent hobbyist use.
In terms of maintenance, it is very minimal because, frankly, these machines are not very complicated in terms of the number of parts and components. Aside from keeping the unit clean and free of dust, the only regular maintenance involves lubricating the bearings once every three to six months, depending on frequency of use.
A. John Lepkowski, owner, EZCNC: There are a couple of classes of entry-level machines: hobby and lightweight industrial.
Lightweight industrial units feature the same linear rails and bearing systems found on their heavyweight cousins; these precision ground, hardened linear motion components are designed for long life. With minimal maintenance, when properly taken care of, they will not wear out. Lower-end hobby machines will typically have V-groove roller or sleeve bearings.
There are several other differences, such as motion control: the motors and drives that move the machine play the biggest role in determining how the machine is used. Lower-end hobby machines will typically be driven with small amplifiers. While these are not bad units, they do not provide the features found on larger, more robust units. EZCNC and other manufactures offer both configurations, so it is important when comparing machines, that the consumer is comparing apples to apples.
The next issue is motors. A good quality machine will have at least a 34-frame motor that will produce the power needed to move the machine through thick material at an acceptable cutting speed without losing its position. With larger motors and quality drives, the machines can run 24-hour cycles, whereas with the lower cost drives and motors, a few hours at a time is about it.
Well built machines should require very little maintenance, just grease the bearings once a week and blow off accumulations of dust. Lower-end hobby machines usually require a lot of tweaking to keep them aligned and running. Be careful of machines that use springs to support the motor, as the springs stretch out over time. A good machine will have gears that are parallel to the rails.
A. Mike Seegar, sales and marketing manager, ShopSabre CNC: When looking at entry-level machines, even some mid-level machines, quality of construction and the components used are two key factors to investigate. When it comes down to it, all that matters is the end user of the machine must be able to produce his parts day-in and day-out without fail. Some machines (typically bolt together or angle iron) in the entry-level price range can run up to three to four days a week, but will require regular downtime to verify that these are square and have not lost position. The fully welded setups, especially those with ball screw drives, are designed to run many hours a day.
With a quality, industrial drive system, the machines can run up to three shifts a day, seven days a week with minimal maintenance. These systems are available in the entry-level market. A CNC with an open design, no end rails or drives above the table surface can add the flexibility of many different sizes of material, while reducing the chances of injuries associated with loading and unloading material.
Typical machines in the entry-level market will range from 3 feet by 3 feet up to 6 feet by 12 feet for the most common applications. A properly designed frame for daily use and for years of reliable use should be able to handle a sheet of 3/4-inch steel plate without any issue. When investigating what the best machine is for you, simply ask to speak to some existing clients and research the drive components and frame structures. This combination is going to give you an excellent idea on what machine will be working day-in and day-out, making you money.
Q. How much training is usually required on an entry-level machine and what is the typical learning curve for a first-time operator?
Burns: There are really two different levels of training needed to incorporate a new CNC into production. One is at the implementation phase and the other is the operational phase.
When implementing a new process, the worker needs to have a full working knowledge of the operational software, the design (CAD-CAM) software, tooling for the materials to be cut and fixturing to hold your parts in place. A new person implementing production from scratch can expect to be in class for two days and on his machine for several more before he is ready for production. Training and support from the CNC company at this time is critical, and it is worth getting away from your daily routine by taking a trip to the CNC factory to get your training.
Once the CNC workcell is ready for production, a new worker should be able to operate the machine in less than an hour. I have witnessed new operators at a large cabinet shop in Indiana jump into the automation process in as little as 20 minutes. Things like indexing and holding your part are all automated to assure success. Safety is built into the process with light curtains to keep the operator completely away from the cutting process. By using a bar code scanner to pull up many cutting files from a list that travels with the different parts, the operator can be productive without having the same knowledge as the worker that set up the process.
Frampton: The software is the key to the whole system, and the provided CNC software is rather simple to grasp. Typical CAD/CAM-based software can take months to learn. Most first-time users catch on quickly and can be up and running in fairly short order by following the supplied instructions. Of course, a certain amount of trial and error is always an excellent teacher. Our partners offer full technical support for the software and programming, including offering a 12-hour training course for those interested in really getting into the programming side of things.
Lepkowski: Buying a CNC machine is not like buying a table saw. Expect to have a long-term relationship with the company you buy from. It is important to buy from a company that you feel comfortable with. My recommendation is to call them up and ask questions. Do you talk to a live person or are you directed to a user group on the Web?
We try to give customers individual attention. Some folks will require lots of hands-on help, where others will pick it up very fast. Generally, those who are familiar with any CAD program will learn the basics of their new machine in a few hours.
If you do not have any CAD abilities, either hire someone who does or take a class, because if you can’t draw what you want the machine to make, it won’t make it. The exception to this is reverse engineering of a part you already have. All major manufacturers offer digitizing probes that will “draw” your part or laser scanners that will scan and digitize your parts.
Software for these machines has become very easy to use and no longer requires programmers. We do have one recommendation for anyone considering the purchase of a router: The worst time to buy one is when you need it or in the middle of a project. You will need some time to get it in, set it up and learn how to use it.
Seegar: Learning curves can be different from person to person. An average person who is a little computer-savvy can run a user-friendly system. A properly designed system should be up and in production in two weeks or less, even for a beginner. The largest learning curve is definitely the CAD software, but with today’s programs, they are much easier to learn and the training is available with a click of a button.
The CAM software is also much easier to operate and will generally look similar to the CAD software. With a good CAM software, you will be able to produce your part with detail and precision, just the way you design it. Programs are even available that have designs already done for you both in 2-D and 3-D. The best thing to do is to download the various demonstrations of each software and play around with them to find out what is the easiest for you. No one can tell you how easy the software will be until you use it yourself.
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