1. #1
    freddi's Avatar
    Lives in Mansfield, United Kingdom. Last Activity: 4 Weeks Ago Has been a member for 0-1 years. Has a total post count of 6.
    Hello MyCNCUK,

    Me and a group of guys are trying to make a multi axis double sided cnc machine that is capable of double sided friction stir welding and incremental sheet forming.
    It is more of a proof of concept rather than it has to work fully as we understand that this is highly unlikely considering our current experience. Some of the requirements include high radial and axial forces.
    We would like to get some information regarding:

    Whether a raspberry pi with I/C expanders would be enough to control the synchronization of the two tools?
    How would we go about the programming when two tools need to be synchronized?
    Any ideas on possible structures, we have considered using steel frames and strong dovetails.
    How we can tailor the machine design to deal with the huge axial and radial forces it would have to withstand?


    Any kind of reply is much appreciated, even if you don't know the answer, anyone with any kind of cnc machine design experience, your help, experience and expertise would be much appreciated.
    Last edited by freddi; 29-11-2016 at 01:36 AM.

  2. #2
    Quote Originally Posted by freddi View Post
    Hello MyCNCUK,

    Me and a group of guys are trying to make a multi axis double sided cnc machine that is capable of double sided friction stir welding and incremental sheet forming.
    It is more of a proof of concept rather than it has to work fully as we understand that this is highly unlikely considering our current experience. Some of the requirements include high radial and axial forces.
    We would like to get some information regarding:

    Whether a raspberry pi with I/C expanders would be enough to control the synchronization of the two tools?
    How would we go about the programming when two tools need to be synchronized?
    Any ideas on possible structures, we have considered using steel frames and strong dovetails.
    How we can tailor the machine design to deal with the huge axial and radial forces it would have to withstand?


    Any kind of reply is much appreciated, even if you don't know the answer, anyone with any kind of cnc machine design experience, your help, experience and expertise would be much appreciated.

    Freddi,

    Firstly save yourself the trouble of messing with Pi's and use a controller capable of slaving axes. Mach3 can slave axes but you could even just write the GCode in a way that makes use of A B and C axes.

    Now what material are you planning on stirring? On a budget, I would forget metals. You would need specially formed cubic boron nitride stirrers and targets and then a good number of horsepowers in the spindles. After all you are frictionaly heating the material and then rotating the stirrer inside it.

    Plastics are a real possibility though and can be done as a proof of concept without much effort.

    Contact me offline if you would like a more in depth chat. I have some experience in working with this process
    www.emvioeng.com
    Machine tools and 3D printing supplies. Expanding constantly.

  3. The Following User Says Thank You to komatias For This Useful Post:


  4. #3
    For the incremental sheet forming Ford's machine gives you an idea of the size and weight required for car body steel -

    https://www.youtube.com/watch?v=iNQ40MYwZqw

    It's a 6 axis machine as it requires two independent 3-axis probes to do this.
    Ford control theirs with code generated by custom written CAM software.

    - Nick
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  5. The Following User Says Thank You to magicniner For This Useful Post:


  6. #4
    A machine like my second build/ my current machine/ will do incremental sheet forming with small ball pointed tool given that the steel sheet / DC04 or similar <1.3mm/ is stretched in a rigid 10mm steel frame bolted to the bed and frame is filled with grease or heavy oil. In fact thats is why the second part of my table has a 70x70cm empty square
    Of course that means long tool paths and nothing of a kind that you will see in 1M$ machine. I have not tested it but have designed the machine with that in mind after seeing some you tube videos where a guy does that.

    But doing that both sides at same time? you will need very rigid frame with custom steel rollers or very expensive roller chain bearings. big ball screws on the Z axis and all servo driven heavily geared. Otherwise your option is to bend kitchen foil only
    project 1 , 2,Dust Shoe ...

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  8. #5
    The only way to do accurate 3D sheet forming that works with any shape is with probes on both sides, some things are possible from one side, lots of things are not.
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  9. #6
    freddi's Avatar
    Lives in Mansfield, United Kingdom. Last Activity: 4 Weeks Ago Has been a member for 0-1 years. Has a total post count of 6.
    Thank you guys. I appreciate the time and effort you have put into this very useful reply.

    Thanks Nick for the video, very useful. And yes, I understand that a real machine that was capable of that would have a value of at least 200 grand or so, we just want to create a prototype to prove that it is possible, it will obviously most likely not work and we don't have that kind of budget or resources.

    The material that we are friction stir welding is a 6mm thick lead sheet as our customer has put this as a requirement but as it is proof of concept he is also happy for us to use plastics but he should prefer Lead sheets to be stirred.

    One current design issue we are having is that we are struggling to create a good axis design to deal with the high radial and axial loads, we were thinking of using hardened steel rollers with large leadscrews, we want to do it as cheaply as possible but still be able to meet the high force requirement, any ideas on this considering there is the 2 z axis (up and down) and then other separate motors to power the machine?

    We have an idea of the rigid frame, it has already been modelled and we know roughly the motors/spindle we will use.

    I appreciate your time reading this message. Thank you.
    Last edited by freddi; 29-11-2016 at 10:35 PM.

  10. #7
    Why then you just scale things down and demonstrate that with ~0.5mm -1mm sheet? That will greatly simplify things. For example then you could use normal 16xx screw from China, 3nm nema 23 motors, cheap drives for the motors, even unsupported 20-35 mm shafts instead of expensive linear supported rails. It will be better if you use instead of ball bearing blocks, blocks that a plane, with special plastic or ceramic elements.

    I will greatly recommend you reading this below. Ignore the acoustic and music stuff. There is quite extensive info on metal sheet forming. Look at the machine on page 55 in document / p. 73/ Figure 3.2: Mini-pan production process . There you could see the machine i am talking about. Just do that both sided.

    Soren E Maloney 2010 PhD thesis.pdf - University of Cambridge


    What i mean is: you can do it with that money.

    The only thing left is to choose the cheap controller that can control all this. It must be Pokeys CNC 57 which on paper ideally could do that, though i had some problems with it, may be because of interferences in my machine. The other controller that could do that maybe
    http://cncdrive.com/products.html

    Anyway, i am not sure in real life if you will not have to use some hydraulic instead of ball screw for pushing. Or a combination of these.
    project 1 , 2,Dust Shoe ...

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