Shopbot.... I know, I KNOW!! Not another CNC thread!!

[Bluetickhound]

Seriously though... I have come into a bit of money and was thinking about spending some of it on a shopbot desktop model. I understand there's a lot more to CNC than plugging it in and instantly carving out tops and backs but does the learning curve for someone like me who is only marginally computer savvy make this a less than well thought out idea? What programs do most shopbot users like? I hear a lot about Rhino and am interested in how hard it is to get up and running with... I also would like to use this for cutting out inlay so any advice concerning tooling/program(s) on that end would be appreciated also.

I had considered another tabletop machine some time ago but abandoned the thought at the time. Now that I have some discretionary $$$ I am revisiting the idea...

[Rob Zamites]

Paging Marty Jacobson, Marty, please report to this CNC thread.

[Jim Adwell]

You're not going to know whether you can do it or not unless you try it. If you are willing to spend money on a speculative venture that may or may not pan out for you, why not try it? You can always sell the Shopbot if it doesn't work out and you'd learn something new in any case.

Did George Washington listen to the guys telling him not to cross the Delaware standing in a rowboat? Did Einstein stay in school and become a businessman? Ignore the naysayers and do what your heart tells you.

[mirwa]

Cnc is simply another tool in ones arsenal,

I made my first cnc router close to 10 plus years ago, Now we have 6.

Steve

[MANNDOLINS]

Most of the software that you will need to learn has trial versions available for free...you can start learning before committing to a machine..
Mach 3, vetric , etc..I think Rhino has a trial version also.. I studied and ran "dry runs" for a couple months while my machine was being built..when it arrived it took a couple weeks to get things going..applying what I learned to the real world ...but after a month or two it was just another tool as Mirwa said...

[Bluetickhound]

I think a lot of folks look at CNC as some sort of magic time saver that does all the work for you... Like others have said, it's a tool. Nothing more, nothing less but it does have several advantages that particularly interest me including repeatability and accuracy. Especially since my initial experiences in hand cutting pearl and abalone have been nice, but nowhere near the quality I've seen from builders who use CNC to cut their blanks... I'm Sure that given time, I could really turn out nice work freehanding it but it would never approach the cleanliness I've seen from going the machine route...

[Dale Ludewig]

I have a ShopBot. Probably have had it for 12-13 years now. My table is about 24 * 36, a little less. And I use Rhino Cad. And you need a CAM package to generate the tool paths. I use RhinoCam. It plugs right into Rhino Cad. Max Girouard also has a Bot and I'm pretty positive he uses Rhino also. The Rhino products aren't cheap. You might be surprised at how pricey RhinoCam is. But it works well.

You're going to have a learning curve but if I could do it, anyone else can. I precarve my plates on the machine and bring them close to final graduations, but I do those by hand. The way I got to that point is using a probe, which ShopBot sells. You put a plate that you've carved manually in the machine and then tell the Bot to sample it, from where to where and how closely. The software then writes the program to duplicate what you're probing. Not a lot of programming work involved. Some, but not huge.

I also cut inlay with it with a 1/32" diameter cutter. That was all drawn in Rhino and depending on the complexity, it can take many hours to do. But once it's done, it's a simple matter to cut the inlay and to cut the pockets for it to go into. The fit is so close that I put the inlay into the pockets dry and then wick watery superglue into it. Sand flat and I'm basically done. No fill necessary. For an all out fern style, I'll probably never get my time back that I spent programming it. But they're perfect, or at least consistent.

The ShopBot people are amazingly helpful and responsive. And really nice people.

[Marty Jacobson]

The ShopBots look good. So do K2's. I think K2's may be a little better value, but less name brand recognition so resale value may not be quite the same. Don't feel the need to spend extra money for servos, it is not necessary for machines like this. The force required to move the spindle around is more than the radial cutting forces (if you're doing it right). So steppers will do the job just fine. There is nothing un-repeatable about stepper-driven machines (unless there are problems with the drivers or calibration).
Also do not underestimate how much Z height you need. I would not recommend that anybody buy a machine for lutherie if it has less than 12" of Z travel. Here's why: Fixtures cut into your height. If you want to machine a guitar neck, your vise or fixturing will probably be 2-3" tall, other solutions become unnecessarily complicated and will be less efficient. Then your guitar neck is probably 3.5-4" tall. And the cutter will be at least 3" in order to get where you need it to go (neck heel, etc.).
So that's 3 + 4 + 3, we're already at 10", and you need some room for moving around and clearance on top of that. So 12" is about perfect. 6" is probably OK for mandolins, but as I said, it makes for more headaches since you can't always hold onto things in the orientation which would provide for most simple machining operations. The simpler the machining operations, the more value the machine has to you.
And definitely consider a VFD spindle, but not at the expense of Z axis height, if it comes down to it.

[Pete Jenner]

This is excellent news Karl. Now I have someone to CNC all my plates.

Seriously though. I have heard good things about the shop bot. I believe Max has recently been doing some unbelievably fine inlay work with his but of course it's taken years of hard work to get to where he is today in terms of mastery of the processes.

Marty Jacobson designed and built his own CNC and it's a real marvel - what Marty can't do with a CNC probably can't be done. He did my headstock overlays and the files I sent him where produced in Rhino. It's not a terribly difficult programme to learn if you follow the tutorials.

I think Dan Voight also built his own recently and is producing very fine work.

[Pete Jenner]

Also do not underestimate how much Z height you need. I would not recommend that anybody buy a machine for lutherie if it has less than 12" of Z travel.

Good point. Max customised his to give him extra Z travel.

[Marty Jacobson]

Another thought.. make sure that your machine is capable of using a touch plate (height probe). This means that you will never have to manually set tool heights or stock Z elevation. The machine probes the location of the tool and the stock using a grounded plate and adds offsets to the work coordinate system so it all comes out right, to about 1/2 a thousandth of an inch. I was losing a lot of time in my cycles by having to manually calibrate each tool height between operations. It may not seem like a lot of time (30 seconds to 1 minute) but there is the opportunity for error and it makes it more of an annoying interruption rather than a quick tool change with the wrench. For Mach3 machines, you can add this functionality yourself, or it should be no more than a $150 add-on.

I use automatic tool change machines all the time, and they are nice, especially if you are making many parts which are identical. But the tool change with integrated probing systems is so easy and effective, I have decided not to worry about automatic tool changers for the time being.

[sliebers]

I have no experience with the Shopbot machine, but I was in your situation about 2 years ago. If you have the money and time/patience to learn new things, I'd say go for it. I ended up buying a CNC Shark HD from Rockler. I selected that one because I have a dealer nearby and I got to demo one. I thought it would be a good unit for an entry level machine. That store also has a CNC club that meets monthly. I've learned a lot from other users even though none of them build instruments.

One thing I did to help me decide was to write down all the things I wanted to do with a CNC and then figure out how to actually draw those things on demo software. My machine came with Vectric CAD software which I found very intuitive and easy to learn. A touch plate is also a must as you will be changing bits a lot. Also, be prepared to spend a lot of money on replacing bits early on, especially with the smaller diameter ones needed for inlay and fret slotting. You will make mistakes, the computer will hiccup, and slam bits into the bed of the machine. Just accept that's going to happen and prepare for it. Eventually, you figure out all the quirks and avoid most of these mishaps, but they still happen once in a while.
I use my CNC for both male and female parts for inlay work, fret slots, fingerboard position dots, etc. I still have not worked in 3D yet to rough carve mandolin plates, but I hope to soon. I also make many jigs and fixtures on the CNC. I can now make custom mandolin tuner drilling jigs very accurately. If you can draw it, you can make it.
I also use my CNC for my electronics business making prototype circuit boards and engraving aluminum front panels for one-off custom pieces. Just make sure you have a clear goal of what you want to accomplish with the machine and stick to that. It's really easy to spend a lot of time drawing up parts, and fiddling with the machine. In the meantime, no building is getting done.

[Dale Ludewig]

Marty is spot on regarding the touch plate. I can't imagine using a CNC without one. On my machine, you can even go into the code for the Z-zero program and change how thick your touch plate is. But! You have to remember for every file (put it in the file) where your Z-zero is or you can watch a cutter plow right through stock/fixtures, and so forth. The damage is done before you can hit the stop button.

[mirwa]

There is plenty of tips and tricks you will learn when starting to cnc, but it is not the bee all and end all, its a tool. And like most tools it takes time to learn and use properly

Example, if I was to cut a strat guitar body by hand and cnc, I would finish the one by hand before the cnc was finished and our biggest one has an auto change 8 tools.

If I was to cut a fretboard and shape it, by powered tools, thicknessers crosscut saws, I can do one in about 4 minutes, by cnc it takes about 35 minutes

But the cnc once running does not need me to do anything, so in reality whilst its running I can now do something else rather than spend that time doing it myself with bandsaws and routers.

Steve

[Jeff Mando]

It has been said before (probably by me) that the Peavey T-60 of the late 1970's was the first guitar to utilize CNC manufacturing production techniques. In fact, every time I see a "vintage" T-60, I have to admit, "that sure is a finely-carved instrument!"