Spindle Synchronisation.

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  • July 30, 2014 at 2:30 am #6523
    RodeoClown
    Member

    I am seeing this more and more on other cheap CNC controllers.

    Basically, an indexer (usually a magnet or slotted disk in conjunction with a hall sensor or optical sensor) is placed on the spindle and connected to any limit switch input. Then TinyG is able to detect the speed of the spindle and move XYZ in sync with the spindle. That way we can tap threads without having to use one of those floating chucks.

    • This topic was modified 10 years, 3 months ago by RodeoClown.
    July 31, 2014 at 12:11 pm #6534
    jlauer
    Member

    Here’s my suggestion using ChiliPeppr. One of the design goals was to let you bind into multiple serial ports at the same time from CP so you could sync your CNC commands with other hardware (thus a hardware fiddle). So, I would setup an Arduino that reads your sensor on your spindle. Then write a tiny bit of code that just spits out the sensor position every 250ms or perhaps when you request it. Then write a macro in CP that binds into the serial port with your sensor.

    chilipeppr.subscribe("/com-chilipeppr-widget-serialport/ws/recv", function(data) {
    if (data.P == "COM4") {
        // this is data from my Arduino sensor
        if (data.D.match(/1000/)) {
            // I'm at 1000rpm, now move Z into aluminum
            chilipeppr.publish("/com-chilipeppr-widget-serialport/send", "G1 Z-2 F100\n");
        }
    }
});
    • This reply was modified 10 years, 3 months ago by jlauer.
    August 1, 2014 at 1:53 am #6543
    RodeoClown
    Member

    The problem is that when the tap starts to drive into the aluminium or steel, it slows down and then the z axis starts to mangle the thread a bit. At the moment I use a floating chuck, but it is a bit slow and doesn’t produce the nicest of threads. If I want really nice threads, I find the best thing is to shove the tap in my 18v cordless drill and cut them that way (if my dad is reading this, this is not your son typing this, you taught him better than that and he would never disrespect his tools like that). It would be to get that first force of a fixed tap for a clean bite, and then vary the z axis feed rate to stay in sync with the rotation and get a clean thread the whole way through.

    This is spindle sync on a planetcnc controlled lathe.

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