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Tom Senior improvements

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  • Tom Senior improvements

    Added a DRO to the quill and made a speed chart that relates to the VFD drive.

    DRO fitted

    Speed chart

    Strobe disc for calibrating.

    More strobe discs.

    Inverter at 50 Htz

    I got the strobe discs to print out here...


  • #2
    No reason why you couldn't go up to 70 Hz wih that invertor.
    This will give you 3,700 at top speed well within safety speed and bearing limits and better for small cutters.

    It might also pay to round off the numbers to make them easier to read.
    Rounding all the last digits to 0 will make it a lot easier

    John S.
    Nottingham, England

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


    • #3
      Thanks John,I will probably "up" it a bit.
      I just spoke to the inverter people and apparently torque drops of quite severely below 20Htz. and motor heat goes up,I shall know better when I put some work on it.

      If I'd known how much better 3 phase and an inverter is,I'd have done it years ago.



      • #4
        My bridgeport at 70 hz sounds like it is going to leave the building.. I have only done it once or twice.

        I had it up to 90 once.. only once.. Geeze almost vibrated as much as a old harley I had.. (made my dongle itch)

        I had a old bike you could watch the screws unscrew.. I blueprinted and balanced it, no more problems.. Hate to see my bridgeport shake loose..

        Over speeding a motor can cause it to overheat. Fans do cavitate.

        David Cofer, Of:
        Tunnel Hill, North Georgia


        • #5
          A ten turn pot mounted close to where you work is pretty good.

          I have somewhere a tach-follower. You input a pulse tach w/magnetic or optical input and digitally preset a speed, it'll up and down the control voltage replacing the pot. I am going to install it just as soon as I get to it.. someday. I think I bought it to tap with.. planned to go onto the B&S drill with tapamatic head..

          Refer back to your inverter manual on pot hookup.


          • #6

            I think the pot you are refering to is the white round knob in the face of the inverter,I just turn it to adjust the Htz.

            It can be programmed to go from 0Htz to 70Htz,also ramp up and ramp down at between 0 and 6 seconds.

            I've fitted an external toggle switch on the one on my lathe to give reverse,although I hardly ever use reverse as the chuck is screwed on.I might put one on the mill if ever I do enough tapping to warrant it.



            • #7
              I wish all inverters were like yours,I'm only now begining to see them with just a display and a pot knob.Used to all you could get were units designed by people who never worked in the real world,to many damned buttons.

              Is that one of the Asian scales?How do you like it,some of the ones I have seen tend to go blank and jump between readings,or maybe I'm just used to my Mitutoyo.
              I just need one more tool,just one!


              • #8

                My inverter has a 270 degree sweep knob on the face, unfortunatly it is inside the screw lid box on the back of the machine..

                The ten turn pot gives really good control. Also, if you do specific jobs "probably" you can program digital points (terminals) to refrence speeds. Example, tapping holes.. or boring.

                I use forward and reverse points on my inverter.. grabbing the chuck gives you a lot of things to think about.. the minor 5volt or 24vdc that controls the inverter.. one pulse and it can turn on with your hand on the mill.. I use my brake.. I am thinking of bypassing the computer on the brake altogether and not giving it control.
                USUALLY no contactor is used in the motor circuit.. only the inverter is in the circuit.
                The brake trips the inverter and won't let it start, that is pretty important to me if I have my hand on a cutter. I keep changing the wiring to suit my changing thoughts..

                David Cofer, Of:
                Tunnel Hill, North Georgia


                • #9

                  I've not put the scale to the test yet,I do know it seems to play catch up when I move the quill.
                  It would seem to be a characteristic of vertical scales.
                  I'm just about to order the "Shumatec" unit that John mentioned a while ago.I can hook my quill unit into that, and I am hoping that it will give a faster reading when connected to a separate display.
                  The scales are all Chinese so time will tell.

                  A few weeks ago my Mitutoyo vernier died and I needed a new one quick so I went to a local tool supply,paid about twice what I would have paid on ebay if I had had any patience.
                  Tha new vernier is not a patch on the Mitutoyo for how it feels,I can't put my finger on what it is exactly but it just does not feel anything like the quality of the Mitutoyo.I frequently find I am reseting zero when I switch it on,it won't be long before I get fed up and get another Mitutoyo.