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4 or 5 axis DRO with rotary encoder angular display

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  • 4 or 5 axis DRO with rotary encoder angular display

    I'm in the market for a (reasonably) low cost 4 or 5 axis DRO configurable to display angular measure from a rotary encoder on one or more axis.

    I have an Abene VHF-3 milling machine. Essentially a knee mill without a quill, but the NMTB40 spindle can be rotated between horizontal 0° with overarm support (shown below) and over vertical to 135°.

    I'd like to set up the DRO for use with the usual XYZ linear scales, and potentially use the 4th U axis in rotary mode to display spindle angle (0°-135°), and 5th V axis for use with a rotary table or dividing head for helical milling (via closed loop stepper ELS).

    I'm interested to know what options are out there and have a few questions for current DRO owners with linear/rotary configurable DRO's

    When configured as a rotary axis, what is the display format? Decimal degrees DDD.XXX or Degrees, Minutes, Seconds DDD:MM:SS and is this configurable?
    Is the display format for a rotary axis impacted by switching between inch/mm (does it toggle between DDD.XXX to DDD:MM:SS for example)
    Does it rollover at 360° back to 0°, or does it continue counting beyond 360° and is this configurable?

    Also interested in thoughts on display format LCD vs traditional 7 segment designs....some of the LCD models appear to have more user friendly interfaces, particularly when performing some of the extended functions such as PCD, PLD and curvature operations

    The Ditron D80 (LCD) and D70 (7 segment) seem to be contenders (the D70's user manual is more informative than the D80 in this regard)

    The user manuals for other low cost options that I've found (eg SINO and ToAuto) are not particularly enlightening !!

    Any and all input gratefully accepted.

    Thanks and regards,
    John
    Attached Files

  • #2
    Only Heidenhain comes to mind that supports a rotary axis readout.

    -Doozer
    DZER

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    • #3
      Thanks Doozer...not sure that's in my price range...but I do accept that may reflect whats required to meet the requirement.
      John

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      • #4
        Every CNC lathe and mill that I have ran employ rotary encoders on the axis drives.

        I suspect your first hurdle will be sourcing a single interface with a 4 axis display for hobby money.
        XYZ and W axis in degrees.

        This is the display only.
        https://www.machinetoolproducts.com/...gital-readout/
        Last edited by Bented; 11-09-2021, 07:24 PM.

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        • #5
          Thanks Bented - I looked up the manual for the Newall DP1200 that you linked to above and it provides a pretty clear account of how it works on that model (incl configuration options)
          Still at the pointy end of the price curve but does help with understanding the functionality that I'm after.
          Thank you

          http://www.newall.com/upload/product...%20-%20usa.pdf
          Last edited by jcge; 11-09-2021, 08:00 PM. Reason: added link to Newell DP1200 manual

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          • #6
            Heres a couple of lower cost DRO manuals I've looked at - any Ditron owners care to comment ?

            Ditron D80 (LCD type)
            https://www.machinetoolproducts.com/...02017.6.28.pdf

            Ditron D70-4V (7 segment type)
            https://zsinstruments.com/downloads/...anual-V2.0.pdf

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            • #7
              And manual for a ToAuto DRO 2V/3V shows some indication of this capability, but does not really elaborate beyond the configuration.

              https://trabiss.nl/wp-content/upload...structions.pdf

              "When selecting the rotary encode, the resolution will be set as follow: Input the rotary encode parameter value ."

              "3.2.14 Setting the Angle Display Mode Press until“ANG DISP” appears in message window. Press to change the angle display mode for X axis;Press to change the angle display mode for Y axis;Press to change the angle display mode for Z axis; Example for X axis: “0.0000” means the angle mode is Circulating DD; “0000.0000” means the angle mode is Incremental DD; “0.00.00” means the angle mode is Circulating DMS; “0000.00.00”means the angle mode is Incremental DMS;"

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              • #8
                All CNC lathes that will thread have a C Axis encoder which only tells the Z axis where to begin the thread, this places the tool in the correct position during the multiple passes often required.

                Most do not display the spindle position as an angle value.

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                • #9
                  Bented - by C Axis I'm understanding that you mean lathe spindle angular position (not displayed to the user). Please correct me if I've misunderstood.
                  Appreciate your input
                  Thank you
                  John

                  Comment


                  • #10
                    Originally posted by jcge View Post
                    Heres a couple of lower cost DRO manuals I've looked at - any Ditron owners care to comment ?

                    Ditron D80 (LCD type)
                    https://www.machinetoolproducts.com/...02017.6.28.pdf

                    Ditron D70-4V (7 segment type)
                    https://zsinstruments.com/downloads/...anual-V2.0.pdf
                    I seem to recall that my Ditron D60 supports a rotary encoder for an axis. I am not home though to verify.

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                    • #11
                      On the D80 any of the 5 axes can be set to either linear or rotary mode. As far as I can tell, rotary mode is displayed as degrees, with 4 places to the right of the decimal point. If there are other options I can't find them. In linear mode, MM: there are always 3 places to the right of the decimal. In linear mode, INCH: there are either 4 or 5 places depending on the resolution setting you've selected. The display resolution setting you choose is universal. You can't select resolution on a per axis basis.

                      The display offers a non-linear compensation mode but there's no way to enter a compensation factor, so you're stuck with only the scale resolutions Ditron offers.

                      As an option, available at time of purchase, one axis may be used for RPM readout

                      BTW there's a V2.0 of the D80 manual available.
                      Last edited by genea; 11-10-2021, 04:36 PM. Reason: Spelling

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                      • #12
                        And there’s now some really nice Ditron heads for sale with LCD’s for around $200

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                        • #13
                          You could just use two DRO displays, one 3 axis and one 2 axis.

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                          • #14
                            RB211 and genea - thanks for the feedback on the Ditron displays - I'll have a look for the D80 V2 manual

                            elf - I hadn't considered using separate displays..I'll consider that too.

                            Appreciate all of the input. Thank you.
                            John

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                            • #15
                              Originally posted by jcge View Post
                              Bented - by C Axis I'm understanding that you mean lathe spindle angular position (not displayed to the user). Please correct me if I've misunderstood.
                              Appreciate your input
                              Thank you
                              John
                              You are correct, the C axis encoder enables the Z axis to begin moving at the correct rotational position, this is independent of spindle speed as long as the lead does not exceed the max feed rate.
                              For the last several I have been running a new lathe with a "Thread Repair" feature, you enter the thread repair screen then rotate the spindle by hand a few times in the desired direction, manually jog the threading tool into a thread by eye and enter a Z value. As you may imagine this slow and tedious, it is far easier to pick up an existing thread on a manual lathe with a compound slide.

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