Getting More from the CNC

There’s always room for improvement.

As soon as any machine is developed, people begin to create ways to get the most out of it. For CNCs, one of the least expensive but most functional new add-ons is a work-holding clamp system from Axiom Precision. It’s called the AHC 109, or the Lateral Clamp Kit.

Holding work steady on a spoil board has always been a bit of a challenge, in large part because traditional solutions have relied on applying downward pressure. Axiom’s solution doesn’t go there. Instead, it provides fixed fences and lateral clamping that doesn’t get in the way of the tooling. It offers a low-profile design that’s capable of holding nearly any workpiece without impacting the top surface. And it offers impressive holding power without marring the edge of the substrate. This kit was designed to fit within the integrated T-slots on the company’s own machines, so shops using other spoil boards should check to be sure there’s a way to make it work. The kit is listed at $99 on the accessories section of Axiom’s website (axiomprecision.com).

Among the most popular upgrades or add-ons for CNCs are aggregate or ‘angle’ heads. These are attached to the spindle instead of a tool and change the angle at which the tool approaches the work. Most swing from the traditional vertical to 90 degrees horizontal and can stop at any angle in between. There’s a trade-off. Depending on the size of the machine, tangential forces generated by changing the direction of the cut can impact performance. The bigger the tool being held by an aggregate at an angle other than vertical, the more likely distortion can occur. On larger CNCs this is not usually a problem, as they are built to tolerate stress created during lateral movement as the tool cuts across a sheet of stock. In small machines, check with the manufacturer first.

One of the most common uses for aggregates after hole drilling is to mount a saw that can chamfer edges, create grooves and perform crosscuts and rips. But sawblades don’t necessarily have to be mounted on an aggregate. Depending on the task, a fixed, horizontal blade may be all that’s needed.

Aggregate heads can perform some of the tasks of a rotary axis or rotary table, so they can be a more economical upgrade for shops that occasionally need to turn parts or work in three dimensions. For shops that frequently turn components, an add-on rotary (lathe) kit that supplies a true A axis may be a better option.

Few enhancements boost production more than the addition of an automatic tool changer (ATC). The ability to switch tools without shutting down or having an operator zero in each tool after a change can radically reduce downtime, especially when lots of different tools are required to make parts. Step one is to contact the manufacturer of the CNC and find out what’s recommended, or even if this upgrade is possible. Be aware that in most cases some mechanical adjustments will need to be made to the spindle, some software will have to be added, and some training or learning must be done. There are a few adapters available for upgrading an existing spindle system with manual tool change to an automatic tool changer, but these are usually for small spindles and most often for a specific brand.

A variation on the ATC is a drill bank, which presents several bits simultaneously to the work as it drills holes in a line. These can be used to install shelf supports, drawer slides, panel connectors, and other hardware. Many larger machines have drill banks that are separate from the ATC.

Heat is the enemy, and there are several options available for adding an aftermarket cold gun to cool a spindle. These simply convert compressed air into a stream of cool air (usually about 50 degrees F) that washes over the electronics enclosure. For larger machines, oil and coolant chillers are available. The result of cooling is a spindle that can work a little harder and faster, with an extended life. The cooling can also benefit the tooling and help it keep an edge longer. Cold guns often come with a magnetic base and a malleable tip, so the air can be directed exactly where it’s needed. That can be helpful if there’s a dust collector at the tool.

Micro-lube misters use oil or organic liquids to cool the process. Oil mist is a factory or aftermarket system that continually atomizes lubricants and reduces the particle sizes, then delivers precise amounts of lube to bearings and metal parts that move. Misting uses less oil than baths and eliminates the need for oil changes. Dry lubricants also have their place. Check with the machine manufacturer for maintenance guidelines and lube schedules.

Dust is created by the cutter, and there’s no better place to trap and collect it than where it is generated. There are numerous boots and accessories that present a brush and a dust port at the point of contact, and these not only keep the cut clean but also help the tool’s life by not requiring it to cut the same material several times.

The most obvious disadvantage with most of these devices is that they visually block the operator’s view of operations. But a clean spoil board is a pretty good trade-off. There are also some devices that mount on the tool shaft and spin with the cutter, creating a vortex that blows dust out of the toolpath. Both options are relatively inexpensive for small CNCs.

Keeping track of cabinet parts can be tricky when so many look alike. It’s possible to have stickers printed from a CAD program and to manually apply them to parts. It’s also possible to add an on-demand printer at the machine.

The problem with stickers is that sometimes they don’t get hidden, and they often need to be removed. It’s a small bump in the road, but shops also have the option of engraving parts as part of the CNC operation, using a pen tool from the design software.

Other options include stamps, barcodes, and an aggregate that slips into an ATC to create and apply labels or stamps.

Every shop has people who approach potentially dangerous equipment when they shouldn’t. It might be an inexperienced new hire, or perhaps an office employee who ventures out onto the floor to deliver a message. Occasionally, a customer wanders in and wants a closer look at the CNC in action. A light curtain (or ‘opto-electronic device’) can flash warning lights and can even cut power to the machine if an unauthorized person gets too close and breaks a beam. A safety mat (pressure mat) on the floor performs the same function when somebody steps on its pressure-sensitive surface. They can also be used around robots that are loading or unloading a CNC router.

Automated placement of stops on a spoil board can reduce set-up time because the sheet goods slide into the same spot every time. It’s possible to add pop-up locating pins (automated or manual) to most machines, and some shops leave the pins in place and use pre-made plywood spacers to set sheets. Pins on a vacuum table automatically retract before the spindle moves, and the operator manually retracts pins on machines where fixturing is used.

Updating the spoil board is a very popular option and is often done using an MDF board that is made on the CNC itself. T-slots and bench hook holes can be milled in as needed for manual fixturing. Some manufacturers also offer a vacuum table as an upgrade.

Upgrading a spindle can be tricky, especially on smaller machines. Some light aluminum gantries or frames aren’t built to handle the added torque delivered by a more powerful motor.

Many of the smallest machines that use portable routers for power simply can’t be upgraded.

But as machines get bigger, so do the options. Most full-sheet or larger machines can handle enormous lateral torque, and some machines can be upgraded with a second spindle, a rotary axis or a lube-cooled rather than an air-cooled option. If the spindle is dragging, the obvious thing to do is check that the tooling is sharp and that the travel speed and cutting depth are appropriate. If problems persist, it may be time to call the manufacturer and upgrade to more horsepower.

Don’t be in a hurry to trade in the old spindle, though. It’s handy to have a spare on hand, just in case the new one complains about the workload.  

This article was originally published in the July 2023 issue.