The pin router in action.
As CNC machines have become more prevalent, how much have they changed the building process?
“The Ballad of John Henry” looms large in the annals of American folklore. Versions of it have appeared in a number of narratives, usually referring to Henry as a “steel-driving” man who dies from the effort of defeating a steam drill machine designed to replace his ilk. Henry, who cuts holes in stone for dynamite with his hammer and chisel or alternately pounds railroad spikes, represents a way of life threatened by a powered machine.
In this clash between man and rising technology we are reminded that the fear of progress is an age-old battle that humans have fought with every advance in tools. So goes the advent of computer numeric controlled machines. Commonly referred to as CNC, these machines can be routers, saws, welders, or any number of robotic machines programmed to do heavy, repetitive work—the kind that killed John Henry.
At first, these machines were so huge and expensive that only large companies could afford them. The software alone could run into five-figure sums, locking out even medium-size operations. In recent years however, the cost of smaller machines has dropped to the point where even hobbyist builders can afford to put one in their garage or basement shop. Yet in the minds of many guitarists, the purity of a handbuilt instrument elevates it to a higher standard. But what is really the difference?
A century ago, guitars were made primarily with hand tools. But by the 1940s, guitar factories used large cutting machines, like shapers and routers, to perform the basic forming of bodies and necks. A staple of the guitar-building trade was the overarm “pin” router. Along with its cousin the profile shaper, it simplified and accelerated the manufacture of instruments. The pin router is extremely flexible and can be used for hundreds of woodworking tasks. The tooling used to create repeatable parts can actually be made by the machine itself by copying an original form, such as an existing guitar body or pickguard.
Other advances in guitar manufacturing have included specialized machinery that followed physical templates to carve necks or create the archtops on bodies. Gibson famously used both these machines, which were originally conceived to make gunstocks and chair seats, respectively. Guitar factories employed multi-head drill presses to drill six tuner holes simultaneously, and mechanized glue spreaders replaced brushes and bottles. Each of these changes increased output and reduced the amount of hand skills required to make a profit. It also ushered in a new level of standardization that reduced human error. Today, a single CNC machine can do all of the above and more.
“Guitar factories employed multi-head drill presses to drill six tuner holes simultaneously, and mechanized glue spreaders replaced brushes and bottles.”
Just the same, there has always been a subset of guitar makers that rely mostly on hand tools. I find it to be the most satisfying part of what I do. For decades, small builders have existed alongside the behemoths as a way of providing the short run or custom work that a large factory couldn’t afford or be bothered to do. The rising success of small builders who focused on handwork paved the way for large companies to create their own in-house custom departments. Now, the versatility, lower cost, and smaller footprint of CNC milling machines allows both types of shops to do a variety of modifications easily and profitably. So, what does this mean for the customer? Do robot machines suck the soul out of an instrument?
The way I look at it, there is a similarity between all means of manufacture. In the case of the shaper and pin-router era, designs had to be drawn by pen and paper, then transferred using hand tools into physical templates. At that point, an operator loaded a wooden blank onto a fixture and muscled it against a spinning cutter along a path determined solely by the template. The creativity and craftsmanship ended before the wood ever saw the blade, and the operator was mostly muscle. In CNC manufacturing, the designer’s pen and paper is replaced by the mouse and computer screen. The nuance of the procedures are determined in the design and tool-path phase long before someone on the shop floor loads the blank and pushes the start button.
The truth is that every instrument is made using some kind of tool, and automated equipment only does a small part of the job. A seasoned builder can spot problems (and opportunities) before they occur, which machines can’t do yet. There is still a huge amount of handwork required to turn a CNC creation into a guitar. If you think that wood, plastic, and steel goes in one end of the machine and a finished instrument comes out of the other, you haven’t been paying attention. It’s just that now electric motors are the muscle instead of John Henry.
Our columnist shares the devices and materials needed to do some of his favorite guitar maintenance tricks.
The problem with giving advice is that there are many different approaches to everything, and usually more than one "right" answer. With my five decades of taking guitars apart, and sometimes putting them back together, I take a lot of stuff for granted, and I admit that I'm still learning. But ignoring all that, I'll just forge ahead and share the inexpensive tools and materials needed to do some of my favorite little tricks.
Alcohol
The solvent, not day-drinking. Pharmacy grade isopropyl is a pretty good at most cleaning chores, and is fairly benign. It's great for cutting through the gunk that accumulates on guitars, and it won't harm your finish. If you've bought an entry-level Jazzmaster slathered with stickers, this is just the thing to get you back to a clean slate. You can usually degrease hardware and de-schmutz fretboards without fear of harming your prized axe. Isopropyl works great on sticky fingers, too.
Naphtha
When cleaning with alcohol fails, naphtha is a DEFCON-level higher. You may know it as benzine or lighter fluid. It's way more caustic than alcohol, and it's also carcinogenic, so wear gloves and a NIOSH-approved respirator rated for organic vapors when you're using this stuff. It's highly flammable (lighter fluid, right?) and dangerous enough that a half-dozen states have banned its sale. Oddly, it's mild enough to use on nitro finishes. I used this stuff for wet-sanding nitro for years, until a sander exploded in our shop. I immediately switched to dry sanding with open coat paper. I caution you not to use this solvent unless it's your last resort.
Tri-Flow
This is as close to a miracle as you can get for $15. A Tri-Flow pen is a great way to lube whatever ails your gear. Got a sticky truss rod nut? One drop on the threads and washer and you're off to the races. Noisy fan? Squeaky bearings? Rusty pliers? You guessed it, Tri-Flow to the rescue. Loosen up those case hinges and hasps. In Chicago, I put a drop in my shop door lock to keep it working when it was 25 below zero.
Flattening Paste
This is some old-school spray-painter tomfoolery. Want to get that dull matte or flat finish effect when painting your guitar? Don't pay for matte lacquers, just add a little of this stuff to your gloss clear and you're good to go. Build up the clear coats with your regular gloss clear, and then do a final coat with some flattening paste mixed in. You won't see it working when you spray, but when it dries, the effect kicks in. Experiment with the formula on a scrap piece starting with a mix of about 5 percent at first, and increase until you get what you want. The crazy thing is that if you don't like the way it looks, you can just buff it out to gloss like normal.
Diamond Nail Files
Luthier supply shops get serious coin for diamond-coated files because they work great and last almost forever. My suggestion is to get a set of German-made diamond nail files from Amazon. You can get a set of five different sizesfor 10 bucks! I use them to deburr sharp edges on bridges, frets, and anything that needs a quick smoothing. Buy two sets and put some in your gig bag. You can also file your nails with them.
Notched Fret Cauls
Check out StewMac to pick up a set of notched fret-press cauls. These things won't get used that often, but if you have a lifted fret at a gig, or if you're just too lazy to take the strings off, this is the nazz. The cool thing is that, in a pinch, you can place the caul on the high fret (the strings go in the notches) and just hammer it lightly with a Shure 58 to reseat that buzzy fret.
Watco Oil
Step up your fretboard prep to the pro level with Watco. Technically a penetrating varnish, it looks great and seals wood against moisture, which stabilizes your neck. Start with a cleaned fretboard, then apply natural Watco on your rosewood or ebony, being careful not to drip any on lacquer. If you're worried, mask off the sides of the neck. Follow the directions on the can. Apply with a soft rag or paper towel, and flood it with two or three liberal passes until it stops absorbing. Don't worry if you get a little on the frets, but generally try to avoid them. Wait 20-30 minutes—that's the secret, so go do something else for a while. Come back and add a light coat and buff to a shine with a cloth. Let it cure overnight.
There are a zillion little shortcuts and tricks you pick up with time and experience, and these are just some of the ones I use almost every day. Like I said, I'm still learning, so I'm passing these on to you. If even one of them helps you out, you've made my day.
