CNC or Hand Work

[David Grier]

Hello MIMF Family....I have a question or 2......I am looking at building my 1st Bass Guitar and I would like to know, if I should pay someone to inout the dimensions into a CNC program or if I should just trace out the pattern and do everything by hand..........which would be easiest?

2nd question......I am looking at getting templates made, what should I have them made out of in order to get the shape tracing as accurate as possible?

[Paul Rhoney]

My first question would be, how are you making your drawings? AutoCAD? CorelDRAW? Pen & Paper?

[David King]

Do everything by hand the first time around so you know what that's like and how quick it is. That way when you get to play with CNC you'll know right away if you are saving or wasting time and money via that process. Each process has strengths and weaknesses and you have to know them first to accommodate them.
Like computers, CNC is dumb. You need to know everything so you can tell it everything it needs to know. How are you going to learn everything first if you don't do it all by yourself?


I would ask you this: How do you know you will not want to edit your shape after you build the first prototype? What looks great to you on paper one day may be a stinker shape when you try to play it in person.
Design is a tricky thing. It took me a year to realize that I hated my first design. Up until that moment I thought it was the greatest thing since sliced bread. I can't imaging spending the next 10 or 20 years being stuck with it.

[Arnt Rian]

I agree with everything David said. Doing it by hand will teach you a lot valuable about stuff you will have to know, no matter how automated your process will be later on.

BTW, you are not the David Grier, are you...? http://www.davidgrier.com/

[Barry Daniels]

I had a stubborn student who insisted on making aluminum templates for every part of his first electric guitar. He took about 3 years to finish it and he changed everything after the first build. Make templates or get a CNC after your 20th hand built guitar.

[Alan Carruth]

Right. CNC is great when you know what you want, and especially if you want a lot of them. You're prototyping to find out if what you have in mind is what you want. Until you know what you want, do it by hand.

[David Grier]

I appreciate all of the feed back, this is why I love my MIMF Family.....I received the Bass Guitar Templates from the MIMF Site....this is going to be my 1st build and as far as formal training goes, I have none. I currently work at Lorain County Community College and I have access to all of the machines in the college. I talked to a couple of the Professors there who are over the CNC/CAD curriculum and they are willing to assist me in putting the measurements into AutoCAD to assist me.

@ Arnt Rian.......I wish I was the David Grier.....in actuality, I am because that is my name also, but I am not the Famous "David Grier"...., I am much younger....lol

[David Grier]

I'm sorry.....I forgot to mention that I am not looking to make money off of doing this, I am a Bass Player/ Drummer for my church and I am just wanting to take some extra time out to build or shall I say try to build me a Bass Guitar to be able to play on church....

[Andy Birko]

Right. CNC is great when you know what you want, and especially if you want a lot of them. You're prototyping to find out if what you have in mind is what you want. Until you know what you want, do it by hand.

I can't entirely agree with this statement. CNC is great for making large quantities of things but it's real strength, in my opinion, is being able to make very complex one-offs or many variations of something without having to jig & fixture up to do so.

Now, a lot of this strength comes from which CAD software you're using for the design as well. E.g., I use SolidWorks which is a fully parametric solid modeler which allows one to make lots of little variations in parts. Once tool paths are created, it simply a matter of re-generating them with new parameters.

E.g., a customer asked me to make a pyramid bridge for them out of a specific material. I didn't have a pyramid bridge in my catalog so I drew one up and machined them for him. I showed the design to someone else and they pointed out that the peaks of pyramids were a little too symmetrical for his taste and the Martin styles had the peaks a little more outboard than mine. So, I opened up the file and moved the peaks outward by about 1/8" which took roughly a minute (not including firing up the computer, loading the software etc.). I then hit the regenerate toolpaths button and in about 2 minutes, I had a tweaked version of the bridge. On top of that, with the software I use, I can store these multiple configurations in the main file so that I have access to both versions.

Using the CAD -> CAM -> CNC process, it's extremely easy to tweak designs and fine tune them to your liking. Granted, it takes a fair amount of experience to be confident that you're not going to make a mistake in your first try at a brand new project but, the same is true with hand work.

So that said, unless you have some really specific ideas that really lend themselves to CNC work or, you simply don't have the tools to fabricate all the parts you need and are looking for more of a "bolt together and finish" type of build, you're probably better off giving it a go with standard tools.

[Paul E Buerk]

I had a similar thought in mind. Pin Routers are also great for making a whole lot of the same parts over and over as well. CNC can do that, although not as fast, especially if it's a predominantly 2D design that mainly uses vertical routing/milling. Tweaking a design, as described above, is another strength of the CAD/CAM/CNC workflow, but I'd also point out that it's useful to maintain a CAD file for such changes even if you're building by hand.

If you work with a NURBS modeler like AliasStudio or Rhino, you're quickly going to come up with things that just aren't practical to manufacture any other way than with a CNC of some sort. IMO, this is where some of the really interesting design work is coming from and a great departure from 2D.

[Andy Birko]

[quote

Until you know what you want, do it by hand.

IMO, this is where some of the really interesting design work is coming from and a great departure from 2D.

This actually brings up an additional point - if you plan on going to CNC at some point, it's best to start out with a CAD model for the prototyping as well. Although there are times when digitizing a physical model is the right way to go, I much prefer working straight in CAD tool using napkin sketches and critical dimensions or whatever rather than trying to take measurements from an existing prototype.

This also helps the refinement process because there is more flexibility in tweaking a design when it was created using the features and tools in the CAD package rather than using e.g. an imported point cloud from scanning a prototype.

Again, for a one off guitar, it's probably about a wash either way. For a simple 2D type design a la Fender-ish, free CAD tools are available that one could draw up the parts themselves and ship off the drawings for CNC machining at a pretty reasonable price....but still more expensive than finding a friend with a bandsaw and spindle sander.

[Barry Daniels]

If one already had a CNC then using it for the first guitar would make sense. But for a newbie that knows neither guitar making or CNCing, getting up to speed on a CNC in order to make a first guitar is absurd (not to mention the cost).

[David King]

Andy,
An unrelated question to you; I think it would be difficult for most guitar makers to justify the cost of a parametric CAD program along with the CAM / post processing package they would need. How did you make that calculation?

I see some movement in the high-end software market towards a pay-per-use model where you are charged a monthly fee while you are actually using the software rather than having to pull together the 5-10K up front. Presumably this will help gather more of the single seat market which must be growing rapidly within the "maker" community.

[Andy Birko]

David,

I decided to go with SolidWorks for a number of reasons but at the time, I had a very well paying "normal" job that helped mitigate the cost factor. My end goal is to design a reliable re-tune mechanism for banduras and the lower end CAD packages simply don't have the horsepower to handle such a complex project. The mechanism I have in mind has a lot in common conceptually with that of a pedal harp which means there are hundreds of parts to model and it will require motion studies etc. I also used SolidWorks before so that was a big factor - I really didn't want to learn a new software package.

However, there is another parametric CAD package out there, Alibre, that's only like $500 which is somewhat reasonable considering. Alibre doesn't have near the surfacing tools of SolidWorks but a few extra bucks gets you MOI 3D where you could do your complex surfacing. In fact, some would argue it has better surfacing than SW.

I guess in the end I kind of lucked out, at the time of purchase, I had the extra cash to go with a good package. Now that I'm doing this pretty much half time, I have outstanding tools to work with.

I've told my re-seller and Dassault many times about my feelings on the cost of the product. It would be fantastic if they would open up the field to lower end businesses to use their product but to this point, they haven't budged and it seems that they don't really need to unfortunately.

[Andy Birko]

If one already had a CNC then using it for the first guitar would make sense. But for a newbie that knows neither guitar making or CNCing, getting up to speed on a CNC in order to make a first guitar is absurd (not to mention the cost).

Barry, I think you're taking a rather closed minded look at the situation. We don't know what the OP has in terms of tools and he hasn't really expressed his goals that well.

If the OP wants to simply make "one guitar" (in quotes because we know that doesn't happen in real life) and doesn't already have a shop full of tools, it may in fact not be a bad rout to farm out some of the work to an established CNC manufacture. Dassault systems has a free 2D drafting package called Draftsight which is more than capable of drawing up a standard style electric bass. Design is the most time consuming portion of the process and therefore the most expensive. Once the drawings are done, it's pretty simple and not even that expensive for a pro to cut out the body shape or even just templates for his guitar shape.

But as I said before, I'm not trying to push CNC on the OP. I originally replied to Al's post because there's a misconception that CNC is only good for mass production. While it is good for mass production, so are a lot of other things such as shapers and pin routers as Paul pointed out. CNC's true strength is the complex one off. And then as Paul pointed out, once you start designing in 3D, a universe of possibilities are opened up for you that may be practically impossible by hand unless you're and expert hand tool woodworker.

[Barry Daniels]

Andy, fair enough.

[Alan Carruth]

I've been thinking about Andy's remarks, and also mentioned the thread in my class the other night. One of the students is a skilled machinist in a local manufacturing firm; he make prototypes, one-offs, fixtures, and other stuff using CNC tooling. He agreed with Andy, and that's what got me thinking.

It seems to me that it comes down to going with the skill you have, and, in some sense, discounting it. I've done mostly hand work for more than forty years, and have gotten reasonably good at it. There are some things I do that I'm not sure would be possible on CNC, although I'm willing to be convinced. In the end, though, it's often easier for me to simply make the thing by hand than to spend time even considering making up fixtures. Also, I have no experience at all with a CAD program like 'Solid Works', but given the work I've done with 'Photoshop' and 'Illustrator', I rather suspect there's a pretty steep learning curve. Of course, the learning curve for high level hand work is not exactly easy, either.

And that's what I mean by 'discounting the skill you have'. It's sort of like the doctrine of 'sunk costs' that the local manufacturer works by: once the money is spent it's gone, and they will write off what I'd consider perfectly good machines simply because they've finished a job and there is no immediate need for them. My tool maker friend is getting a couple of machines worth together several hundred thousand dollars. One argument he used was that they are trying to get out a new model, and lose $30,000 a day for every day it's not out. If he can speed things up by a week or two the new machines are paid for, and they could throw them out afterward to make room if that made sense.

When I started out, hand tools were all that I could afford. CNC was hardly even a gleam in the eye of major manufacturers, and, at any rate, there were no home computers. Now that everybody has a computer, and the tooling gets cheaper, more capable, and more easy to use all the time, it probably makes some sense for a newbie to just go that route.

Of course, I'm still a hand tool advocate. As far as I'm concerned, learning how to do it by hand will always be the best foundation. I've seen students ignore the characteristics of the wood, such as grain direction, when they're using a machine, and get into trouble thereby. Even if you don't blow stuff up, it's always more efficient, and gives a better cut, to work with the wood rather than against it. Besides, being able to just keep working when the power goes out, at least as long as the daylight lasts, is a good thing.

[David Grier]

Ok....to clarify my intentions....I am just looking to make 1 Bass Guitar for my own personal preference....I am more into cabinet making and outdoor furniture. I asked this question because they say that it is always nice to play something that you made rather than something that was purchased......I have 8 Bass Guitars to date that I have paid for and I look at how much I invested into the purchase of them. I just want to be able to play something that I put work into to fully understand the feeling of putting in work, if I can use that. I have invested well over $10,000.00 in Music Equipment and I am just looking to have a project that I have made for myself by myself.......GOD BLESS!

[Peter Wilcox]

I am just looking to have a project that I have made for myself by myself

Then there's the answer to your question. And you can make your own templates out of 1/2" or 3/4" MDF.

[Eric Baack]

If you have access to a printer that can do 11x17" prints or larger then you can always do "printer CNC" for making templates. I draw the parts up in solidworks and then print them out in 1:1 scale (with a couple of dimensions to verify that it is actually 1:1). I can do a carve this way as well but running cut planes through the profile and printing it out so that the line where the cut plane intersects the surface is shown. It lets me rough cut the shape with a router prior to breaking out the grinder.

I have built a 3 axis router table that can eventually go CNC, right now it is just hand cranks, but it is nice for surfacing things and making nice straight cuts and grooves. It is basically a mill with a router head.

I'd go with templates in your situation, you could even free-hand things depending on what tools you have access too. An oscillating spindle sander is great for getting that body outline where you want it if you don't have a template and good flush cut router bit.