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Welcome to 2023 Here is the first Luthier Tips du Jour video of the year. - The topic is CNC and lutherie
This video as well as all my other videos are available via my website, https://lutherieacademy.com/videos , LMI's website or on Youtube.
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In the spirit of new year’s, new beginnings, self assessment and etc….

To me the math on CNC is very simple. Robbie, you guys said it at the end but it would have been better served to be at the start of the video. That is, what is your goal?

There are eleventy billion guitar builders out there. Take a look at Instagram, if you dare. There are literally hundreds probably thousands of posts a day with “got the binding on the latest”, myself included. There is little that’s new and SM, LMI, etc… enable just about anyone to build a GLO (as Brian Galloup calls it).

So if your goal is to build a guitar, maybe two, maybe ten and give them to family and friends then by all means go forth and conquer.

The CNC provides an ability for a single builder / small shop to scale and drive efficiency into the workflow. This doesn’t mean putting a log in one side and a guitar comes out the other. It means building tools, jigs, parts to accelerate the building process and to make it repeatable. Can you do this all by hand, of course! It’s been that way since forever. However if the goal is to scale up the output, and the work is all done by hand, you need more hands (or less sleep ).

To summarize, what is the goal? If the goal is business and scalability, treat it that way from the outset. It’s pretty tough to scale a manual process so why design the workflow today for maximum friction later?


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To me, adding a CNC machine to my shop years ago meant that what used to be stacks of router jigs (taking up lots of space I don't have) now live on a thumb drive. I've used it for a lot more than that the longer I've had it, but before I retired I was an IT guy and doing CAD/CAM work came very easily to me. Mainly I use it for making forms and specialized tools as well as operations that I was already doing by machine (slotting fretboards, for instance). The two guitars I'm working on right now (an acoustic and an electric) have CNC cut fingerboard slots and the acoustic has a pyramid bridge that I used CNC for. Everything else was either a hand tool, a router with some jigs , bandsaw and drill press. But a lot of jigs I use with these tools I designed in CAD and cut on a CNC.

CAD work, even if I never cut the part I'm designing, is a also great tool for visualizing things without wasting wood. I enjoy CAD design and machining the same way I enjoy instrument making. So as said earlier it really does boil down to what's your goal.

Dave

I consider CNC gear as neither verboten nor essential to guitar making, either for fun or as part of a small guitar making operation for money. It’s a great tool, but not the only great tool. As with any tool, it comes with its own costs and benefits. My good friend Brad (as do a few other friends) makes great use of it. Others do fine without it. I don’t see its use as part of a binary, pleasure vs. business, choice. I have friends who build guitars with CNC gear, 100% for fun. And with a certain set of goals, I can see a modern day guitar builder doing without it, and making some small amount of money in the process. I do think that setting goals is essential. So is considering “cost” as a holistic concept. In other words, on the question of the use of CNC, if you have to buy the right kind of CNC machine, learn how to use it, learn how to use it to make the parts you want, and learn how to hold the parts (from what I understand, a big part of the challenge), there are financial costs, time costs, space costs, opportunity costs, frustration costs, etc. if all of that is already baked into the cake because of some other job, endeavor or pastime, you are ahead of the game. If not, well, those things are not free. I fully support my friend Brad in his use of CNC, but I also don’t consider it as essential for everyone who might want to do this for money. There is so much handwork involved in making a decent guitar that the question of whether the neck (as one example) was cut with a CNC router or via some clever analog process is, to me, not as big a part of the whole as some might think. As Brad said, you don’t feed a log in and get a guitar out the other side. I’m pretty big tent about guitar building. However you want to get from A to B is cool with me.

This is a good point and important distinction. You can of course accomplish all the same outcomes by using jigs, whether shop made or commercially manufactured. Using robo sanders and router bits to get to the same A to B is just as fast if not faster than using a CNC. Both jigs and CNC give you the measure once (program once) and repeatability. I would not at all question the ability to run high volume production without a CNC. We just had that recent thread with all the manufacturer videos, it’s how real production largely works.

What was in my mind (stuck in my craw? ) after watching the video was the comment about “feeling the chisel in my hand” and how that is somehow diametrically opposed to a workflow that also includes a CNC. I use a chisel plenty, and probably in all the same parts of building as most of us. Unless you’re chopping the mortise in the body with a chisel, etc… there are only a few processes that truly demand a use of a chisel and even those can be simplified (ex: Gore’s brace peaking jig using a taper bit).

However… and I will refrain from ranting too much, the idea that if you aren’t Geppetto toiling away in a darkened basement you aren’t really (hand) building is absurd. I feel it’s important not to get too romantic about it.


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Can you imagine the backlash Charles Fox received when he introduced the side bender?

At the end of the day we use the tools we’re comfortable with and enjoy using. Guitarmaking is one of those rare pursuits where Cervantes doesn’t quite apply, because while the journey here is extremely satisfying and fulfilling, the inn is the goal. As Brad said, sometimes the low-tech approach is the most effective, but because we all have differently evolved skill-sets, sometimes it’s not.

I don’t draw very well by hand and used Illustrator to create a body shape that spoke to me. I was able to take that drawing and import it into CAD/CAM software in order to make bending forms and body molds using CNC, but it was a little easier for me to do the cutaway form on a disk sander by hand.

I thought the waist of that guitar was a little narrow after I built it, so I used Illustrator to bump it out a hair and made the forms and molds all over again.

I know there are other ways to do it, bc I’ve done them in the past. But now that I have access to CNC and know how to use it, I just preferred doing it that way.

We can all get pretty passionate about the tools we use. Which binding jig do I prefer? Should I use a CNC for this task? My vise is the best. At the end of the day, it really comes down to you do you, because the ultimate goal is to build the guitar and get to the inn.


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To me, what used to be using sheets of poster board and refining lines there now goes to CAD instead, but then I still use a pen in my CNC to draw on poster board and refine the lines there... Just another tool, but a powerful one.

I learned to build from Charles Fox, and always took the Fox bender for granted. His jigs and tooling have always been over the top in genius. CAD/CAM/CNC have overshadowed that kind of genius to a point, but really have actually accentuated how genius they really are.

Dave

All that matters is: are the instruments good?

I agree. I build for the joy of building one or two a year by hand.
I try to use mostly hand cutting tools.
I do use CNC for cutting shell and making templates.
I got to the point of my hands and eyes just not being good enough for small precision work.

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A CNC machine is just another tool you have to plug in. Some people don't feel that using tools you have to plug in fit the definition of "handmade". I'm not one of them.
Improvements in tooling have allowed us to produce parts more quickly and accurately, but if the guitar is to be greater than the sum of its parts it still requires the human touch (and/or perhaps a bit of luck )

Considering CNC for cutting pearl and inlays, I'm a little disappointed with this thread, as I thought I may learn something. It seems to be more about the pros and cons of using CNC rather than how to use it.( this isn't apparent from the title)

There is an OLF sub-forum for CNC work. Go to the main index and scroll down; you'll find it.

Thanks, I'll have a look. Mike.

One thing that helps to put the advice in this video into perspective is to watch the video, and every time one of the speakers says "CNC", replace that in your brain with the word "router." Both are production enhancing machines. Any argument for or against one applies to the other.

I've been using CAD/CAM/CNC for many years, and advising luthiers in their use for almost as long. This latter experience points out to me one critical difference between these two technologies. CAD/CAM/CNC are highly technical, and as such they are simply not accessible to all that want to make use of them. There is and will continue to be a certain amount of commodity-ization that will make these technologies more generally accessible, but I have serious doubts this technology will ever be as accessible as that of routers.

It was interesting to me (and it may be of general interest, so I'll summarize it here) that my standard advice for folks wanting to get into these technologies evolved to be highly weighted to the fact that the majority of people attempting this would not fully succeed. Which is of course a shame. It is a phased approach that does not require big upfront expense, and that is of use even if not fully realized. FWIW it is basically:

1. CAD drawing. Stick to 2D drawing and printing out drawings. A background in basic drafting will help a lot. Books are available on that subject. This will be immediately useful in drawing plans and making templates. Folks that are overwhelmed by a fully featured CAD system can sometimes ease into this by using software with only basic features;

2. CAM. It seems that for anyone that understands machining technology and the terminology used to describe it, getting how CAM works is pretty straight forward. For those that don't have this background, books on machining can help to get it. Stick to 2.5D. Make heavy use of simulation;

3. CNC machines, 2.5D machining. Here is the first high expense item. Even low grade machines are pretty expensive. But usually anyone that has gotten this far can readily learn to make good use of a real machine. Folks tend to seriously underestimate the time expense of work holding fixtures. But a tremendous amount of real lutherie work can be done even with the 2.5D limitation. In my observation almost everyone can get this far. Folks with the appropriate background tend to get here quickly, but simple perseverance and a lot of work can do wonders as well. But the next phase tends to present a major obstacle to a lot of folks;

4. 3D. Learn 3D CAD (solid modeling). Apply it to the machining of 3D parts;

5. Learn parametric solid modeling and apply that to the machining of parts. I know of big production shops that don't get here;

6. If needed, learn multi-axis CAM and machining.

rm

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R.M. Mottola
LiutaioMottola.com

Author of the books Building the Steel String Acoustic Guitar and Mottola's Cyclopedic Dictionary of Lutherie Terms.

CNC does seem to always open a can of worms. Some see it analogous to buying a kit guitar and assembling it while others say it's the same thing as using a drum sander or a router. Personally I don't care either way and I have no space for one, no need for it, nor the desire to learn how to use one. But ultimately many if not most of the people that buy guitars I make would not buy one had they known any part of it was manufactured by CNC machines. They like the idea of the guy who lives in South West Virginia who builds unique one of a kind guitars in his one room workshop with vintage tools and the occasional bandsaw. It's part of the story. Sometimes I just don't mention the fact that I bought this fretboard pre-slotted

I can think of several parts that would be really nice to have a CNC machine for. Necks being one of them. Once you have carved out the perfect neck it would be wonderful to be able to replicate that for ever. But as the guy in the video mentioned if you are a small builder or hobbyist then you probably enjoy carving necks and or only sell a few gutiars a year so the cost of CNC is simply not worth it.

It makes sense anyway you look at it depending one what you are trying or want to achieve.

Maybe politics, religion, or Brazilian football clubs would have been safer topics.

I've spent 30+ years in metal machining / manufacturing with CNC, CAD, CAM, etc all along, so adding a little CNC to the shop was pretty easy to me.
I use CAD/CAM to drive CNC machines all day long, so I'm not always interested in going home and sitting down at a computer again....but it's just a tool, one that's more accurate than my hand skills at a number of things (fret slotting, inlay, body molds, electric guitar bodies), so I use it. I've got T-style guitar bodies set up right now and will probably run a few while I'm at it.

I made my first guitar in 2001. I built my first DIY CNC in 2006, when literally no one else a I knew even knew what a CNC was. Why? I like building stuff.

I know people who have made their own hand planes out of exotic tropical hardwoods. Why? Aren’t Stanley’s good enough? I have a friend who made his own classical rosette from dozens of little pieces of wood he himself cut. Why? It took him weeks to make something he could buy for $15. It gave him joy.

I use my CNC to make guitars I probably could make with older tools, but I’d rather use the CNC I designed and built myself (my MKIII, and still not as good as a $2,000 one I could get from China). I like the mental challenge of working with such and unforgiving tool that can, if rarely, produce spectacular results.

Honestly, how many of the thousands of forum members make their living by making guitars (you repair guys can lower your hands)? I would wager less than a dozen.

The rest of us build for the joy of the process. Whether you use CNC because it gives you pride that you made your own tool, or because you find it to be useful in your own personal path to building makes no difference.

Build from a kit, mil up wood from an old tree in your yard, buy premade necks from AliExpress, make your own varnish. Who cares what tools you use, as long as it brings you joy.


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I think in the not too distant future as the price of the machinery comes down and file libraries become more available, CNC machining will become more popular similar to what 3D printing has become. Many of the people I know who do 3D printing do not generate their own CAD/CAM files - they find them online and download them, often from shareware.
There is no reason CNC routing can't do something similar if standards and protocols could be developed to allow files to be shared among different machines (or someone develops a McCNC that is the - Apple - of everyone's eye that takes a large share of the market).
Considering the present state of the art, and my limited through put, and the fact that I rarely build the same thing twice, CNC might not benefit what I do.

I use CNC in luthiery because it’s a lot of fun! Can I build a guitar by hand? You bet! Do I want to spend 100 hours doing an inlay on a $5k guitar? Nope! I think there is room for whatever approach you choose to pursue and all are valid -

Cheers, M

Has anyone thought about creating a library of CNC files for recreating the most popular and iconic guitars? Solid body electrics might easily lend themselves to this, but acoustics could also be done.

I have seen folks on guitar related CNC groups on Facebook who have created a library of files for cutting electrics.

I was considering doing a series of videos, and may still do it, showing practical uses for CNC in building instruments. Everyone jumps to necks and electric bodies, but there are loads of ways to improve the output of a small shop that don't include those bigger ticket items. R.M. hit the nail on the head, there is loads of benefit before you even get to 3D modeling.

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I have just in the last 6 months started to use CNC more seriously. I did have a small Chinese made machine used for inlay but bought a bigger and more robust machine in June last year and have been using it to do things that are difficult to do well by hand, or impossible by hand because of the precision required. Things such as cutting a perfect oval sound hole with oval rosette. Have been trying to get that perfect for 30 years and fail every time. There is always a slight wobble that I have to disguise and it drives me insane. With the CNC machine it is a piece of cake, perfect every time. That is just one example. So, no regrets at all with the CNC purchase. Mr Mottola has it dead right. Start at step 1 and work from there. I am still 2D only, but there is a lot I can do in 2D, have only scratched the surface so far. Some people want to run a marathon before they can walk with CNC and find it too hard (e,g, 3D carve necks as the first step). If you have not done it as your profession before, walk before you run is dang good advice.