A CNC machine is the largest, most expensive, and most complicated piece of equipment found in most shops. Taking a peek under the control panel of one of these machines is enough to make my head spin. The complexity of ensuring thousands of switches and sensors are regularly communicating perfectly with hundreds of mechanical parts to cut up a sheet of melamine boggles my mind. In light of the technology in front of me, my job of choosing the right machine should seem downright pedestrian, even though it hardly does.
In the last installment, we looked at the main features of the machine (table, spindle, and vacuum size, Z-clearance, pod accessibility), and how I would customize them to serve our needs. Today, I will look at some additional features that are offered and decide whether they are necessary, worth the cost, or are just over complicating my decision making process.
Many machines have the ability to break the table top into multiple vacuum zones via mechanical valves, which gives you the ability to run vacuum to only a section of the table top at any one time. This feature can be beneficial if you have small or difficult to secure parts. The smaller vacuum zone will give greater hold down pressure, since more vacuum is being concentrated in a smaller area, or, if your machine has dual vacuum pumps, will give you the ability to use only one pump, thereby saving wear and tear and electrical cost.
I won’t worry about this feature to much, since most, if not all, of the higher-end machines come equipped with 4, 6, or 8 table zones.
Fixed vs. Movable Gantry
The gantry is the rack where the extra cutterheads rest. The main benefit of a movable gantry is that it allows for quicker tool change overs, since the extra cutterheads are always right there with the spindle. For us, this is not an option worth upgrading to, since that kind of extra speed is not really necessary. On the other hand, if you are looking to squeeze every last second of production from your machine, it may be worth the investment.
The drill block is the one optional piece of equipment that I am most on the fence about. The drill block head sits next to the spindle head and has an assortment of drill bits to speed up the process of drilling shelf pegs, RTA fittings, and dowel holes. Keep in mind, the main spindle head can drill any hole you regularly need by going to the gantry and picking up the necessary drill bit. The drill block just does it a whole lot faster, and frees up a few of the tool openings for different cutterheads. Initially, I had absolutely no interest in spending $6K-$10K extra just to speed up the drilling of shelf pegs. Lately though, I have been focusing on purchasing a machine that is slightly more than we need, so that we can grow into it, rather than growing out of its capabilities soon after we install it. At this exact moment, I am planning on spending the money up front to have a drill block installed at the factory.
Remote Control Keypad
Many machines are equipped with a remote control keypad, allowing the user to control various aspects of the machine, such as speeding up or slowing down the travel speed, or shutting off the spindle, without having to walk over to the computer station. For us, this is an unnecessary option, since most of the time, if the operator is at the machine, he will be within a few steps of the main computer anyway.
Overall, I am well on may way to deciding what options and features are necessary for us to get the most out of the CNC machine, and which features are just luxuries that can be passed over. In the next installment, we will look at the machines that were at IWF this past August in Atlanta, what features they offered, and how they fit into my framework of perceived needs.
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