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  1. #1
    Hi there

    I'm experimenting with instrument making, and looking into either getting a CNC machine at home or outsourcing at the beginning. I have experience with 3D designing, and use 3D printing and work with wood.

    I'm still figuring out how best to design some parts, whether they're going to be strong enough if carved out of a block of wood, or whether some part will be aluminium, how thick to go etc

    I have some initial designs which I need made up. Hope fully by someone here - I'll post on the Projects, Jobs and Requests forum.

    And I'll be interested in reading about peoples experiences of building their own machines. I'm sure I'll be getting someone to build one for me!

  2. #2
    Welcome!

    Apart from all else, i make small musical instruments- kalimbas. Which i designed acoustically and then engineered from scratch. Though deceivingly simple, i have made hundreds of experiments deciding on this or that and bettering them with each batch.

    What instruments are you making or starting to make? Maybe i could help you if i can, about deciding the materials or sth. else. Tell us more.
    project 1 , 2, ...

  3. #3
    Hi Boyan

    Thanks for getting back to me. I've had a chance to look at your build. Looks amazing!

    I'm experimenting with small keyed xylophones.

    I'm wondering if I can make the main casework out of timber, machined on CNC. It would be like a large wooden pencil case, or dough bowl at the bottom, housing most of the mechanics. This would be hopefully milled out of one block:
    Click image for larger version. 

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    Click image for larger version. 

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    And there would be an aluminium shape like this, secured above it, around the keyboard. Hopefully this could also be CNC'd?:
    Click image for larger version. 

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    Ideally I'd like an accuracy of +-0.1mm. Is this realistic?

    And a machine with a working area of at least 500mm x 200mm x 120mm (Z)

    Thanks

  4. #4
    Well, definitely looks possible! :-)


  5. #5
    Quote Originally Posted by Grambot View Post
    Ideally I'd like an accuracy of +-0.1mm. Is this realistic?

    And a machine with a working area of at least 500mm x 200mm x 120mm (Z)

    Thanks
    0.1mm is more than achievable and your cutting requirements are also very easily achieved. Thou you may find little more than 200 will be more usable and give more scope.

  6. Last edited by compositepro; 05-10-2016 at 10:59 PM.

  7. #7
    [QUOTE=Grambot;84109]Well, definitely looks possible! :-)

    That on the video is an example of lazy cnc-ing or test cnc-ing. He uses a bit i will use only for sth smal like 50x50mm. i can make that bowl on my machine faster than he, using 1/2 or bigger cutter. Plus he does not use roughing at all.




    My instruments were 0.01mm overall even on my old machine which was to say "flimsy". "Overall" means in some places could be and is worse, but on wood that's not a problem. In reality now with my machine i have always to slow down things and spend time adjusting perfectly toolpaths so to avoid chipping. So at the end whatever they say, but CNC is an art


    So you don't need super fast machine , real life 10 000mm/min will be ok. 5000mm/min will be slow to my liking, but it will not be bad if your machine can reach 20000 mm min so you use HSm techniques there like digging full depth / see my video/ . What happens at the video is at 16000mm/min. The problem though is that now i don't use that toolpath, cause it makes a lot of noise and around me people pay to live in quiet near the sea
    You will need servo drives and motors for that speeds. And looking at that bowls i greatly suggest that, otherwise they will take forever to make


    in fact one of the reasons to build my machine was to make my instruments more 3d, like the bowls. And soon i will start experimenting with the sounds of it, ast shape must be matched to sound in my case
    Last edited by Boyan Silyavski; 06-10-2016 at 06:34 AM.
    project 1 , 2, ...

  8. #8
    What happens at the video is at 16000mm/min. The problem though is that now i don't use that toolpath, cause it makes a lot of noise and around me people pay to live in quiet near the sea
    You will need servo drives and motors for that speeds
    Boyan why do you think you can't run at 16000 mm/min with steppers?
    ..Clive

  9. #9
    Quote Originally Posted by Clive S View Post
    Boyan why do you think you can't run at 16000 mm/min with steppers?
    Because i have never seen it achieve serious speeds except on RP builds

    As far as i know to reach let's say 16 000 mm min on a xx10 ball screw you will need to spin that motor at 1600rpm. At 200 steps per rev then resolution will be mere 0.5mm . So microstepping then and loss of the incremental torque. The acceleration also counts when fast machine is desired, and many changes of direction have to be made when routing large 3d file.

    At the other side for the machine to be able to work at that feedrate the gantry and Z should be very strong / ok, just strong-not talking OTT here/ which means weight

    The spindle to achieve serious feed rates and deep cuts or fast shallow cuts with big cutters needs to be powerful. In fact the way i see it my 3kw spindle is limiting me now, not the speed that the machine could achieve. Though more or less i am finding now that my machine is well balanced. Anyway, i wanted to say that the 3kw spindle needs serious Z axis. Otherwise the bit will be prematurely dull because of vibrations.


    So i don't see 100kg gantry on small machine moven by steppers at that speed. Not to speak of 200kg gantry on 8x6 machine. From what i have read in forums and builds i have looked and studied, people using steppers normally achieve 5000-mm min on a normal build and 10 000mm / min on the better thought builds. I doubt that this 10 000mm /min is really usable with good acceleration on actual cutting, not rapids.


    I am not sure about current prices but 4x30 +4x80 =440 euro for 4 Leadshine drives plus motors. When at the same time i said it many times here for a bit more/ ~200/ you could get the cheapest servo motors plus drives. Which i believe is to be more reasonable considering a good build.

    And now after testing the cheap chinese controller for a couple of weeks- Let's cut this money from the expensive controllers.
    Last edited by Boyan Silyavski; 06-10-2016 at 09:18 AM.
    project 1 , 2, ...

  10. #10
    Thanks for all this info everyone. This is so valuable for me.

    My instruments were 0.01mm overall even on my old machine which was to say "flimsy". "Overall" means in some places could be and is worse, but on wood that's not a problem. In reality now with my machine i have always to slow down things and spend time adjusting perfectly toolpaths so to avoid chipping. So at the end whatever they say, but CNC is an art
    Does this mean, I'll be spending a lot of time getting the right toolpath and speeds etc, and eventually I'll have a program which I'll be able to keep using for one particular design?

    in fact one of the reasons to build my machine was to make my instruments more 3d, like the bowls. And soon i will start experimenting with the sounds of it
    I'm also interested in trying out many designs, timbers to see what effect it has on the sound.

    The problem though is that now i don't use that toolpath, cause it makes a lot of noise and around me people pay to live in quiet near the sea
    Yes, it does seem loud. I'm wondering if I can use my machine at home during the day without too much extra soundproofing. I know how to soundproof, so its not the end of the world, but it would be great to be able to occasionally leave a window open :-)

    If not, I have to hire a small place somewhere, as I don't have a garage. Where do people keep their machines? Or I suppose it must depend on how big/noisy they are?

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