Using CNC for Bass Building?

[robobass]

After reading “Mathew’s Bass Building Project” I was surprised at how traditional tools and methods are still the focus of bass luthiery. I don’t want to knock them, but if I were going to build a bass, I would try to get as much of the rough work as possible out of the way with modern technology, and leave the hand tools for the fine work at the end. There are commercial fabricators out there who own big 3+-axis CNC routers and who, if you brought them the glued up stock and good cad files, might be willing to cut a top and round back for you for like 500 bucks. This is certainly how all these Chinese instruments are being made. You might even score such a machine for yourself on Ebay, software included, for like the cost of a really good bow.

Now, it isn’t all as simple as that, of course. You need to get access to some good cad/cam software, learn to use it, and have the cleverness to be able to translate the shapes you want into digital surfaces. A pretty daunting task, yes, but compared to carving out the shape with hand planes…I would look into it anyway.

I realize that you just can’t just decide on dimensions and make a good bass. You need to decide where to leave extra thickness and thin later by tapping and intuition, for example. All I’m saying is, the technology is out there now to eliminate much of the grunt work that goes into making a bass, and it is now affordable.

I have no ambitions myself on these lines, and am no master of 3d surfacing, but I did own a CNC knee mill, and still implement the technology for my Capo project. It is a wonderful thing, and I think it is ripe for exploitation by American bass builders. I would like to see it happen. I would be happy to provide any assistance I can to anyone who is curious.

Robobass

[toman]

I've been into woodworking for a good part of my life, and while most of my experience has been with power tools, I have recently become more interested in hand tools. To my surprise, making things by hand is not only much more enjoyable, it really doesn't take all that much longer, especially when you're talking about things that have to be shaped, like a bass top or scroll. Now sure, CNC would be a quicker way to do it, but in order to ensure any kind of quality control you'd either have to have super consistent material supply, or you'd be having to finish and fine tune each piece by hand. I just don't think you're going to ever get the same results as a hand built instruments, and the end effect would be detrimental to the industry as a whole. I think we really need to do our best to support the small time independant guys who are keeping both the old basses and the new ones the fine instruments we want and need. The more we commercialize the industry, the harder it is for these guys to eat, and in the end we all loose, even though you might save a little money up front.

[Jake]

I read that the Wan-Bernadel basses are hand carved as well as Ken's Shen Basses. Does anyone know which Shen basses are hand carved and which, if any, are CNC?

[toman]

I don't know which Shens, if any, are CNC, but my 7/8 maple flatback is definately hand carved, as it has visible gouge marks left on the top in a couple spots.

[Eric Rene Roy]

The problem with CNC is you cannot change things. Different wood, even from the same tree, can be quite different in density from piece to piece. Part of learing how to arch and graduate is learning how high your arching needs to be, how much recurve, how robust/flat, etc. The same can be said for graduation thicknesses. I may think I want X for a thickness...and then change my mind and go thinner or thicker depending on flexing the plates and tap tones.

Perhaps on some of these CNC instruments where every one has the same specs is why some are duds, some are ok, and others knock your sox off. What do they say, even a blind squirrel will find the occasional nut!

(sorry, Bean Town boy here...I never use socks)

[Ken McKay]

If I could find 7 people that would order the same bass design I would surely automate some of the processes and make some really nice basses. After all the work designing, doing hand work, assembling and finishing I could have ordered 7 nice basses from Sam Shen and made more money. And Sam's would be more marketable, and probably better sounding!

I do have a CNC guy that I work with on other projects who could easily do it for me for a very reasonable price. I could supply him the wood and he would send me back the 7 carved plates in about 2 months or so. The First 57 days would be projects in front of me and the last 3 days to carve them out. He would go as accurate as I would tell him. If I wanted the chanel routed for the perfling and all the fluting he could get it pretty exact. It would be fairly expensive for me to have him do just 7 plates. He would need to get drawings, convert them to CNC code, make jigs and fixtures to hold them down during cutting. Break even would be (insert number) plates.

I could build a duplicarver in a day, carve a copy plate the next, duplicate it 7 times in a couple days using cheap labor. Figuring about $10 per hour for cheap semi-skilled labor that is $240 plus about $400 for duplicarver parts and $800 of my time totaling $1440. Figure $300 for spruce for each = $2100 + 1440 = $3500 /7 = about $500 per plate to make in house, pretty reasonable, I think.

I could also order them from China. I know of a company there who sells necks and carved parts to spec. Made with Himalayan Maple and Spruce.

But, wouldn't you rather buy a fully handcarved instrument from me? I start by selecting the wood from my stash, bringing into my shop where it acclimates for a while. Rough the wood to dimensions for the parts, glue the top and backs, dehumidify the wood to 7% ECM and carve the plates. As I finish carving the plates I listen to the wisping of the shavings as they come off the plane and imagine how the plate is going to vibrate and sometimes I encounter a little variation in the grain of the spruce and I may leave it a few whisps thicker there in that area just because of the feel of the shavings comming off the plane may seam little weak. It is really hard to describe and seems a bit voodish, but there is magic, or intuition, or vibrational auditory cilliary feedback, or...

[bejoyous]

The book Matthew is using is "So You Want to Build a Bass" by Peter Chandler. Peter made my bass and I'm out to his house regularily to visit.

He uses a small rotary grinder of some type (it kind of looks like a small circular chain-saw) to rough out the front and back. He says the bass starts at about 200lb and ends up around 20lb. That's a lot of whittling!

Of course, he uses the small planes to do the fine work.

[jonas]

Maybe it's disappointing for many of you to read this, but many (the most?) of the basses from Germany are not carved by hand. Actually, there's one major supplier in Germany who sells white basses to many of the well known German makers.
Is it time to think different? Hand carved basses fom China, CNC-carved basses from Germany???
Using CNC for carving top/bottom does not mean that the makers don't do fine tuning and carving by hand at all. If you want, you can leave enough wood to do the final carving by hand, and just let CNC help you to save time for the really critical tasks in bassmaking.

[Bob Branstetter]

Originally Posted by Ken McKay

He would need to get drawings, convert them to CNC code, make jigs and fixtures to hold them down during cutting. Break even would be (insert number) plates.

I know of several shops in the US that routinely use CNC carvers. While I have not been around when they "programmed" it, the process required that a pattern (top, back, neck, etc) be made by hand and then the CNC machine would systematically run a stylus over the pattern measuring and recording the precise height at each and every location on the pattern. Once recorded, a router cutter would replace the stylus and the machine would reproduce the part from raw wood. The really nice thing about it is that you do not even have to make a full size pattern. Just make a scaled down pattern and let the machine do the upscaling for you. Pretty slick. It is pretty common for a shop to use the CNC to have the machine carve the outside precisely, but carve the inside overly thick so that the actual graduation is still done by hand. If you see several instruments by the same maker and they are EXACTLY the same, it's a pretty safe bet that there is a CNC or a big pantagraph carving machine doing a lot of the "hand" work. BTW - Shops that use CNC machines usually locate them in a room or building away from where customers would see or hear them running and would only admit that they use one to the FBI (or equivalent). It helps to perpetuate that image of the luthier slaving away with a chisel working by candle light.

[hdiddy]

Tops and Backs are one thing, but what about necks? I thought most replacement necks bought from various bass repair were CNC'd? I thought I read this on tb somehwere. It would make more sense to me to CNC a neck - especially the volutes.

[jonas]

Originally Posted by KSB - Ken Smith

The two Shens I have SMOKE most newer German Basses I have played under 20k.

Maybe, but now I tell you the secret: we Germans use to keep he good basses in Germany, and only sell the bad ones for twice the price to the USA ... that's why.
(just kiddin ... )

[Ken McKay]

Originally Posted by Bob Branstetter

I know of several shops in the US that routinely use CNC carvers. While I have not been around when they "programmed" it, the process required that a pattern (top, back, neck, etc) be made by hand and then the CNC machine would systematically run a stylus over the pattern measuring and recording the precise height at each and every location on the pattern. Once recorded, a router cutter would replace the stylus and the machine would reproduce the part from raw wood. The really nice thing about it is that you do not even have to make a full size pattern. Just make a scaled down pattern and let the machine do the upscaling for you. Pretty slick. It is pretty common for a shop to use the CNC to have the machine carve the outside precisely, but carve the inside overly thick so that the actual graduation is still done by hand. If you see several instruments by the same maker and they are EXACTLY the same, it's a pretty safe bet that there is a CNC or a big pantagraph carving machine doing a lot of the "hand" work. BTW - Shops that use CNC machines usually locate them in a room or building away from where customers would see or hear them running and would only admit that they use one to the FBI (or equivalent). It helps to perpetuate that image of the luthier slaving away with a chisel working by candle light.

Hey Bob, how you doing?

If I went from a drawing my CNC guy could do it without me having to carve a copy blank. Of course I could also carve one and send it to him to scan. But that would put a bunch of work back on me.

Funny story: I watched a video of Gibson recreating the Clapton ES335 guitar that went up for auction at half a million or something rediculous. Gibson borrowed the instrument in order to copy it exactly and make a limited run of exact copies, right down to the hare krishna sticker on the back. During the video they scanned the neck using a laser to get exact coordinates to enter into the CNC program. But in the next scene, they made a big point of showing Bubba "our best neck guy" hand shaping the neck by eye on the big sander.

Here's the video link, pretty long: http://video.google.com/videoplay?do...07652331081865

[robobass]

Hey Jonas,
Are a lot of fingerboards cut with CNC in Germany? I ask because the Poellman I play in Goettinger Symphonie has a board that is just plain perfect. I have never seen such a nice board in the States. It has a mathematical evenness that to my eye seems unlikely to have been cut by traditional hand/power tools. I wish I could have boards like this on my own instruments.
Robobass

[jonas]

Originally Posted by robobass

Hey Jonas,
Are a lot of fingerboards cut with CNC in Germany? I ask because the Poellman I play in Goettinger Symphonie has a board that is just plain perfect. I have never seen such a nice board in the States. It has a mathematical evenness that to my eye seems unlikely to have been cut by traditional hand/power tools. I wish I could have boards like this on my own instruments.
Robobass

I never visited their workshop, so I can't say what type of machines they use for making fingerboards. But you could ask them: http://www.klier-josef.de

I think that every fingerboard blank needs to be dressed after beeing glued onto the neck, no matter how precice it has been machined before. And you can't use CNC for fingerboad dressing on a complete bass. So in your (or better: Göttingen's) case, it's probably just superb craftmanship.

[Bob Branstetter]

Originally Posted by Ken McKay

If I went from a drawing my CNC guy could do it without me having to carve a copy blank. Of course I could also carve one and send it to him to scan. But that would put a bunch of work back on me.

It could also be the type of CNC machine being used. The ones I was referring to were specifically designed and built for making violin family instruments and don't require any special jigs or fixtures. Still, I have to wonder if my (the luthier) time to make a pattern is worth that much more than the CNC programmer's time. I made a lot more money when I was programming than I've ever made as a luthier.

[peasandhoney]

bottom line is economics. hand built instruments are what the market demands, and those that dont buy plywood basses. i'm sure a great bass could be made with a CNC mill, but the time put into the project would not pay off (ask jeff about his delve into machine tuners). if or when someone makes it pay off, we will see them (machine made basses) take over the market.

[robobass]

To address several posts:

1. Yes, of course you need to dress the board after gluing it on. But, if you are CNC carving your boards in-house, or ordering them to spec, you can fine tune the outer dimensions to the particular neck, and plug in a stock surface shape. This means that you start with a board that has minimal overhang, and therefore needs very little dressing. I think they (Poellmann) must be doing this.

2. I think that modern surfacing software has gotten so good that a skilled user can make adjustments very quickly and easily. I never got to this level myself, and never owned software like this, but I have seen skilled users making changes in surfaces on virtual parts much faster than I could have carved them on actual parts, and I consider myself to be a truly exceptional carver. And, as a carver, one can only take away stock. I reject arguements that CNC limits you to selling one shape over and over. You've just got to be prepared to invest in advanced software, and do what it takes to learn to use it!

Robobass

[jonas]

Originally Posted by robobass

1. Yes, of course you need to dress the board after gluing it on. But, if you are CNC carving your boards in-house, or ordering them to spec, you can fine tune the outer dimensions to the particular neck, and plug in a stock surface shape. This means that you start with a board that has minimal overhang, and therefore needs very little dressing. I think they (Poellmann) must be doing this.

Probably! As far as I know, Pöllmann owns and uses CNC. And they sometimes use a very special shape (profile?) on the underside of their fingerboards: the have two hollow channels, not just one. (Looks not like "n", but like a flattened "m" from the tailpiece point of view.) So we can suppose they make their blanks themselves, and they probably use their CNC for that.

[Matthew Tucker]

I have used woodworking machines and don't enjoy it. big noise, big dust, possibility of big mistakes. That's why I got my wood pre-thicknessed by someone else. I have a friend who makes furniture in a big woodwork shop and he never uses a plane or chisel. Just machines, particularly the table saw and belt sander. I went along one evening but - not for me.

I think if I worked on carving a top solidly, I could get it done in a day or three.

If I were to set up an assembly line, yeah I'd look at ways to do a lot of hack work with machines. I used a table saw to cut out the ply for the mould, much quicker and better.

But, working slowly (cos its the only time I have) its fun, not physically hard, and I can learn about lots of things as i go.
At the moment, the process is as important as the result - possibly even more important for this first bass! The planing might look hard, but its not. And quicker than I expected.

the other thing about programming pantographs/robots is that there's a longish setup time (=expensive if its not your machine) and you usually need to do at least one test each time you change a parameter, just to be sure. That could get expensive with bass wood.

[arnoldschnitzer]

Originally Posted by jonas

As far as I know, Pöllmann owns and uses CNC.

Actually, no. I've been in both their shops, and they do not use CNC machines. They do, however, use mechanical duplicating machinery to rough out tops, backs, necks, etc. It saves a lot of time and lets them concentrate on the details, which they do extremely well.

In my opinion CNC machines are well-suited to production environments where many copies of a particular part need to be made accurately. It is an efficient means of roughing-out very precise parts for instruments. Of course those parts still require handwork before assembly.