Use of CNC machines?

Construction and repair of Classical Guitar and related instruments
WernerMrazek
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Joined: Mon Mar 13, 2017 3:28 pm

Use of CNC machines?

Post by WernerMrazek » Fri Mar 31, 2017 9:24 pm

This may be an inappropriate question in this forum. However, since I have poor eyesight I am interested in using CNC machines and would like to know whether such machines are used by anyone on this forum, and if so, what they are used for.

I would also be interested in what type of machine and software you use. I have an X-Carve from Inventables and intend to use it for designing and carving parts like braces, bridges, heel and tail blocks, jigs,... I will use Autodesk Fusion 360 for CAD/CAM.

Regards,

Werner

Bruno Piancatelli
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Re: Use of CNC machines?

Post by Bruno Piancatelli » Fri Mar 31, 2017 11:07 pm

Hello, I own a laser CNC cutter and find it useful for making routing templates, and general templates in MDF and acrylic such as fret scales markers.
I also cut tiles for rosettes or inlays of solid wood with some great details and precision. I must say that I didn´t buy the machines for lutherie use, instead I work with them, and this woud be a side purpose. Since these are not so cheap machines.

Here are some pics of stuff i´ve done with laser.

Image
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Marcus Dominelli
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Re: Use of CNC machines?

Post by Marcus Dominelli » Sat Apr 01, 2017 1:22 am

Very interesting Bruno. The level of accuracy and detail are quite impressive.
I once talked to a guy about having a bunch of bridges CNC routed to my specs. I was just going to give him a box of rosewood blanks and he'd go from there. The price was reasonable, but in the end I decided that I'd rather have the flexibility of doing them in small batches, as I like using different woods and different specs to achieve a particular sound.

It would be nice to have a CNC for necks....but then again most of my clients want a particular neck shape, which must be done by hand to be efficient.
Of the four guitars I'm making now, all the necks are a different width and profile. So I guess I won't be using CNC anytime soon....

Grooveman JS
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Re: Use of CNC machines?

Post by Grooveman JS » Sat Apr 01, 2017 2:50 am

Yes...... technology has a footprint over everything in our lives. CNC machines are all about accuracy & consistency. Taylor Guitars uses the CNC cuts for various guitar parts of their instruments. People who employ these machines are usually into batch or mass production guitars; at least that's when i think it makes sense to acquire a costly system like this.

In time to come, Digital Printing could very well be the alternative or complement to CNC tech.....
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Bill B
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Re: Use of CNC machines?

Post by Bill B » Sat Apr 01, 2017 3:40 am

Iwas in Gallup guitars a year ago and saw some very impressive cnc work there. Unbelievably clean work. I can't imagine getting that kind of precision by hand. But then I'm not a luthier.
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jim watts
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Re: Use of CNC machines?

Post by jim watts » Sat Apr 01, 2017 4:50 am

Marcus Dominelli wrote:...
It would be nice to have a CNC for necks....but then again most of my clients want a particular neck shape, which must be done by hand to be efficient.
Of the four guitars I'm making now, all the necks are a different width and profile. So I guess I won't be using CNC anytime soon....
I have quite a different take on this than Marcus and maybe it'll help with people on the edge of deciding on the technology to do a little investigation on their own.
First, let me state that I don't really use a cnc router for guitar work. I have one that I purchased years ago used but it is a disaster of a machine. Circles don't come out round, squares are not square, etc.. but that's whole other story.

So, a little about my background. I've been a user of CAD/CAM packages since the early 1980's specializing in aircraft surface development, quite heavy on the CAM side of the house which also required you to be heavy on the CAD side of the house. As you can imagine the systems back then were quite large and expensive running on main frame computers. I can remember a single seat of software costing close to $100K. This was a very specialized field at the time. Times have changed! Enough about that, I suppose that's most me reminiscing about the "good-ole-days".

But the main point of all that was that times have changed. The above history lesson is what set the tone for where we think cnc is appropriate and where it's not. Most people associate cnc with large production houses making large volumes or very complicated parts. This view is no longer true as the cost of entry is minuscule compared to the past (still somewhat expensive for a guitar builder).

So, one of the biggest changes in the technology and most beneficial besides the price drop and ease of use has been 'parametric solid modeling'. This development which occurred back in the mid 90's was designed to address situations like Marcus's concerns about different necks for each client. This technology breaks the paradigm of "large volumes/complicated parts'.

With today's CAD/CAM systems, dimensions and spline shapes in similar parts can easily be changed and regenerated into a different configuration very quickly, assuming the model is set up well. As an very simple example I can change a fretboard model from 650 mm to 640 mm simply by editing a few key parameters and regenerating the model, assuming I put some thought into how I build my model I can be ready to go back out to the cnc machine and cut the new scale in a matter of minutes . This is much faster than making a fingerboard scale template (at least for me). The same can be done for neck contours, widths and thicknesses, of course this is more complicated, but very doable.

Here's my list in no particular order of where I think cnc makes sense for a guitar builder. I think this is the low hanging fruit.
- necks
- fingerboards
- bridges
- some types rosette work
- end block
- inlay (steel string)
- Jigs and fixtures

They won't help in my opinion with things like bracing.

I hope you didn't get too bored with my lengthy post. Things are much different today than they were in the past. I think this technology can really shine for many types of artisans , but getting the market to accept it is another story.

WernerMrazek
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Re: Use of CNC machines?

Post by WernerMrazek » Sat Apr 01, 2017 8:12 am

Thank you for your replies.

I agree with Jim. The rules of the CNC game have changed significantly over the last few years. My machine, for example, cost me around 1200 USD. It is true that it is a hobby machine, but it still has better accuracy than I can obtain manually. The software I mentioned is FREE for hobbyists. The big investment is time. There is a steep learning curve for both the machine and the software. Since I am retired that is not so much of a problem for me.

During the last 20 years I have, as a hobby, built 10 classical guitars manually. One of the reasons for buying the machine was actually flexibility. Since I want every guitar to be different to maintain my interest in building, new jigs and parts can easily be redesigned with the software and produced by the machinine. For example, to generate a slotted fingerboard I use a script with relevant parameters like scale length, number of slots, width at nut, width at 12th fret, etc. This gives me a basic model of a specific fretboard. By simply changing these parameters I can generate another model in seconds.

My ultimate dream would be to be able to model and carve a neck, at least in a rough form. However, I am not sure that I will ever get there. The first challenge is to create the model. The second challenge is to find a procedure to carve it on my simple machine,

dec11ad

Re: Use of CNC machines?

Post by dec11ad » Sun Apr 16, 2017 5:37 am

have used a cnc milling machine. used solidworks with hsmworks to post thr gcode, works quite well for jigs and luthier tools!

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Manuel Najera
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Re: Use of CNC machines?

Post by Manuel Najera » Mon Apr 17, 2017 6:17 pm

IMO, there are few jobs that a CNC is worth the money and time spent (on the learning curve) regarding guitar making.
It is more accurate on jobs like inlays, neck and heel carving, may be slotting a fretboard? (I have not seen a cutter or a bit that small). But still, I do not think there is an actual need for that type of accuracy. I think the most important goal for a guitar maker is SOUND, and we all know that is achieved by hand (on the making) and time (on the selection of the woods and the overall design).
I have, however, relied on a laser cutting CNC machines to have a lot of templates made for: head shaping and slotting, fretboard slotting, heel and neck carving, back assembling, fretboard contouring, etc. That being said, I do not see myself buying one in the near future.

Andrew Pohlman
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Re: Use of CNC machines?

Post by Andrew Pohlman » Mon Apr 17, 2017 9:47 pm

My amateur luthier friend owns a CNC machine - but I don't know the make. I do know we use Punch ViaCad Pro for the 3D modeling and layouts.

He has a pen bit to draw on brace, bridge locations, etc. He uses a laser bit for really nice "wood burning" top decorations. The bed is big enough that we can cut out tops and backs, and route the rosette channels. Making necks are a God send as there is no way I want to carve a neck by hand (we do the scarf joints manually via jigs). He has even made an arch-top top on the CNC for a friend of ours. He carved what looks like the masthead of a pirate ship on the headstock for one guitar. Inlay goes without saying. He has a cut pattern for a steel string bridge. I'm working on a cut pattern for a classical bridge. The list goes on. Production line? Not really. Cutting tops goes fast enough, but most parts take many hours (overnight) to cut out on his machine. The set up takes good chunk of time too.

If we ever get the arithmetic down, we want to make pre-intonated nuts and saddles - but that may prove to have too many variables that need adjustments in-situ...

He has dedicated a MacBook "laptop " to the CNC machine and he knows how to convert 3D CAD drawings into cut instructions.

There is a weird learning curve too. For example, reference points. The accuracy depends upon setting up your reference points accurately - and not cutting them off while cutting out the desired part(s). We have done "tricks" like taking a photo of the LMI classical mold, importing that image into the CAD drawing, then making the guitar shape match the shape of the photo. That, rather than actually drawing the exact LMI classical shape from scratch in CAD.

Having said all that, my bud is a computer consultant, and I am a former computer dork - now I teach Nurses computer record systems (among other things). So the computer part is second nature for us.
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