CNC programs

Discussion in 'Plans, Designs & Software' started by Drake Guitarworks, May 9, 2013.

  1. Drake Guitarworks

    Drake Guitarworks New Member

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    Hi folks...I have a few questions about CNC:

    When a luthier buys a CNC machine to carve bodies and necks, how does that machine get programmed?

    Does he have to write his own programs?

    Are ther preexisting programs the luthier can obtain and load into the software?

    Where does the luthier obtain the programs?

    Can an Adobe PDF be used for CNC?

    I've seen videos of people making their own strat and telecaster necks and bodies on their own tabletop CNC machine. How and where were they able to get the programs for those guitars without having to deal with thorny legal issues of intellectual property?

    Any help you can give me, or direction to others who might know, is much appreciated.
    Thanks!
    Brad
     
  2. Heretic

    Heretic Well-Known Member

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    There are basically 3 software layers at play here:

    CAD

    CAM

    CNC Control

    CAD is something like...AutoCAD, TurboCAD, DraftSight, etc. You design your part and save it in some standardized format, like DXF. CAD software can be expensive...or it can even be free. There are good very high dollar options, good free options, and good options in between. AutoCAD, Rhino, TurboCAD, and DraftSight are pretty popular CAD solutions...at varying price levels.

    The CAM software imports those DXF drawings and create gCode. Most good ones of which I am aware have some means of automatically generating the gCode, which you then tweak to perfect the manufacturing process of whatever you are making. gCode is a tool path. When you think about CNC, think about moving the tool around. In most cases with guitar CNC, it'll be a router of some kind. So how do you move the router's cutter around to cut the thing out? That's what gCode does. CamBam (http://www.cambam.info//) is a pretty popular CAM program, and it's pretty inexpensive.

    You can, of course, manually write gCode. I know a few hardened old machinists who know how to do it. But really, there's little reason to do it anymore.

    CNC Control software is what actually takes those gCode instructions and communicates with the CNC controller hardware to actually move the tool around. There is a physical interface between the PC and the CNC machine (usually a parallel port connection). The CNC control software issues instructions to the control hardware, and the control hardware moves the cutter along its various axes as instructed. When something goes wrong, it's generally because the instructions are wrong. Mach3 (http://www.machsupport.com/) is a commonly used CNC control software package. Also relatively expensive.

    Or so I'm told.
     
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  3. Drake Guitarworks

    Drake Guitarworks New Member

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    That helps, thank you!
     
  4. Sixstring63

    Sixstring63 New Member

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    I've been a CNC programmer for the past 15 years. Like the other post said you'll need good software to make a G code program the the CNC runs from. It will work on a X,Y,Z coordinates system. To go from CAD or Solid Works for design you will need a CAM system software to write the G code for the CNC. MasterCam and GibbsCam are the two I've worked with and are very expensive but there are cheaper alternatives. Besides writing the G code program it will have to post properly for the M codes on the particular brand of CNC. M codes very from one CNC brand to another. It can be quite involved for a novice to CNC. I just retired and want to build guitars and I was thinking this rout myself.
     
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  5. PDotson

    PDotson New Member

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    What would be a good free version of CAD software. I'm an Adobe Illustrator user and have been drawing my plans and templates in that so far, but would like to transition over to making 3D plans that could be sent to a local company for CNC.
     
  6. jcsimons

    jcsimons New Member

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    I worked with a friend who is a cabinet/furniture maker and has been doing CNC work for years for his business. He feeds the G code to a ShopBot (CNC machine). I wanted to build a Les Paul guitar and carve the top using a copy carver, but I needed a model or fixture to work from. I should have just gone down and bought a Gibson and used that, but no, I thought that I could computerize it using a couple of different paper plans on my friends computer. It took a year working on it 3 hours per night, 1 night a week. Some of that was sorting out where we were the week before, but a lot of it is just plain working it and then re-working it.

    Its a very intense experience, but I don't think that its worth it unless you're going into production - certainly not for one guitar and probably not for 5 either, unless you like computer work better than wood working...
     
  7. bruce bennett

    bruce bennett Active Member

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    I spent 8 months of just weekends working with a professional Mastercam user to get all the programs needed to make our JBD-800 guitars.. then we spent another 3 months test running those programs on a Haas VF-3 machine to work out any program bugs.. of which they had many.. (I learned that you should NEVER just trust an untested program)

    here is a photo one of the results.

    [​IMG]

    but..

    the bill was frightening.. the results were great and the repeatability is amazing.. but the time and money won't be justified until I can sell over 3000 units...

    CNCing guitars, can be a VERY serious investment, if you don't already have the machine and the skills.
     
  8. Heretic

    Heretic Well-Known Member

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    Honestly, I think if it takes you that long to work it out...you're doing it wrong.

    Perhaps it's just my background as a computer programmer speaking, but the stuff just isn't that complicated. I've worked closely with designers and machinists, and I have come to the conclusion that a lot of the mystical haze around CNC (and machining in general) comes from people wanting to protect their secret sauce. It's just not that big a deal. It's not that hard, at least when it comes to fairly simple machines like 3-axis CNC routers. Add those other two axes in, and it gets a lot nastier to deal with. However, as far as small-scale guitar manufacturing is concerned, a 3-axis machine should be able to handle just about anything you want to do without a lot of fanfare. They're not terribly expensive, either.
     
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  9. jcsimons

    jcsimons New Member

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  10. bruce bennett

    bruce bennett Active Member

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    If it not that complicated and you have a real handle on it.. Then I have a LOT of work for you .. if you want it.

    and the Haas VF-3 was 74K on a lease program.
     
  11. Leo

    Leo Member

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    If you have a Mac then Rhino3D beta is free until it's ready for release - which is not expected to happen any time soon.

    I've been using it for years and I'd highly recommend it.
     
  12. Leo

    Leo Member

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  13. jcsimons

    jcsimons New Member

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    We used Rhino on a PC (not a free version though) - very cool s/w. Helps to have either a big screen or even 2 of them.
     
  14. PDotson

    PDotson New Member

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    So is it better if you own a smaller or even homemade cnc, or outsource to someone local.
     
  15. Heretic

    Heretic Well-Known Member

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    I think it depends on how many guitars you are making. If you're doing a handful each year, it'll be cheaper to outsource. If you're doing a handful each month, you may think about buying or building your own.
     
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  16. bruce bennett

    bruce bennett Active Member

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    that's a rather hasty statement..
    if there is one thing I'm dead sure of its that you can't just draw a program and go straight to CNC... Well you can.. but the odds of getting anything useable are low.

    ie. On just our necks alone ,we had to create 5 different programs to make one neck.. and each one had its own set of issues and or fixtures to build.. and once the programs were issue free.. we still had to work out the correct sequence in which to cut the necks.
    Certain jobs must to be done in the proper order to keep from taking too large of a cut at given points. it took us 12 trashed necks before we found the perfect sequence. which included two fixture changes.

    but after that every neck made was perfect and only required a very light sanding with 220 to fit the neck to the pocket. and they came off the machine requiring only installing the truss rod and glueing on the fretboard. and they were ready to sand and finish.

    we could have done all this in about a month had we had full work week/days to work on it. but doing it over 1 or 2 six hour days per weekend.. it stretched out to 8 months.. but that's all the time I could get outta the guy and the machine shop.

    and I've found that CNCs CAN BE an excellent time waster as well.

    a Local friend who also builds custom guitars but only uses CNC his machine will cut a body in roughly 2 hours. while I can do it by hand in about 45 mins. and he can't even build a neck WITH his CNC because his programming software and control software can only handle 2.5D code. his system cost him over 10K for a K2 machine and computer his programs cost him 1K each from an independent programmer and he still can't fix something that goes wrong like a blowout which happens often with CNC routers because his shop has almost zero woodworking tools. He is primarily a painter and wouldn't know the first thing about woodwork.

    Now I'm not saying that CNC is not a great thing.. I'm just pointing tout that there are a WHOLE LOT of people that extol the virtues of CNC and never bother to tell you about the pitfalls. and I'm here to tell you CNC manufacturing has MANY pitfalls.
     
  17. BWGuitars

    BWGuitars New Member

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    Bruce nails a lot of things on the head in regards to CNC.

    I've been working out the CNC manufacturing process as I've been building. It's a continual process and learning curve the way that I've chosen to do it, and every guitar that I build I get that much closer to solidifying my methods. But I've been at it for a year, and have a LOOOONG way to go before I have all of my fixtures and programs 100% solidified.

    That said, for *me*, it's TOTALLY worthwhile. I love the level of accuracy that it lends to my builds in regards to fret positioning, pickup cavity routing, neck pockets, bridge screw and string holes, and control covers/cavities/recesses.

    I'm still doing a lot of stuff by hand, and Bruce is completely right about the speed issue. There are a lot of things that a competent luthier can do faster than a CNC by hand, but for me it's the John Henry thing in that once I'm completely confident in a 2 hour body routing/carving program, I can step over to the assembly bench or the sanding table and do something else while Miss Sweettart cuts away.
     
  18. bruce bennett

    bruce bennett Active Member

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    I believe in a two fold approach.. there is no doubt that some jobs a CNC would be the better choice for accuracy and speed.
    Others jobs.. not as much
    ie. I noticed that you mentioned "Fret positioning"..

    Now here IS a job that I DON'T believe CNC is the better/faster way. not saying it doesn't work or shouldn't be used..I'm just saying its not the "best" way.

    I'm positive that a gang arbor slotting saw is the best most accurate way and without a doubt the fastest as I can cut all 26 slots and both end of boards in 1 minute to depth ..
    and with zero chance of bit breakage.. WHICH in CNC.. CAN cause a positioning problem IF your machine runs on for a long while before the broken bit is discovered and the machine is jogged back to the break position. its just becomes an opportunity for the CNC to lose or gain a step or two during the jog back to the break position.

    but for carving a neck a CNC comes out WAY above the curve.
    for cutting inlays, it totally makes that job fun instead of the tedious chore it often is.
    I even like it for cutting bodies

    Once I can afford to get the type of machine that I feel I can "trust" ( like a Haas or Fadal) then I will likely go that way full time.
    but I've now had 2 of these smaller "hobby" machines and they just can't hold a tolerance to suit me.
     
  19. BWGuitars

    BWGuitars New Member

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    The only thing with frets is: about 25% of my business is multiscale. An arbor saw would do me no good for 1/4 of the guitars I build. CNC makes more sense than about any other option for those fingerboards (for me, anyway).

    Inlays and stuff like that, a CNC can offer up options that either aren't humanly possible to do manually, or just aren't realistic to do manually due to the amount of time that would be involved. Like the inlayed top guitar that I'm doing. It's possible to do that manually, just not a realistic option due to the time it would take to accurately inlay the top into the body by hand.

    Overall, I still do a lot of stuff manually, either with jigs or by hand, but I still have a lot of operations that I do with the CNC that makes it an invaluable tool for my shop :)
     
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  20. Sixstring63

    Sixstring63 New Member

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    Absolutely correct. Machining is more than making a program and throwing in to the machine and hit cycle start. It is an art form in itself to make things work properly. Being able to think the whole process out tool per tool and workpiece holding is a lot to do. Kills me when peeps say just run a cad/solid works convert and go. Much more too it than that. Like I said above I have been a programmer for 15 years and a certified Toolmaker for 20+ and there is a lot more to it than turning on the machine. Even though I dealt with metals of all different varieties which involves speed ad feed calculations for each type, the machining of wood is no different and involves the same principals. Hell, just choosing the right ball nose tool for lace cutting a contour on a neck could mean treasure or trash. Nice work by the way on your beautiful guitars. Good luck on your endeavors.
     

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