Myford Super 7 – Convert from Imperial to Metric

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Myford Super 7 – Convert from Imperial to Metric

Home Forums Workshop Tools and Tooling Myford Super 7 – Convert from Imperial to Metric

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  • #94193
    chris j
    Participant
      @chrisj

      So guys, this weeks challenge should you wish to accept it is to talk me through the process of converting the above.

      I think I will look to use a DRO of some kind on the top slides but wonder about the screw cutting aspects.

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      #16841
      chris j
      Participant
        @chrisj
        #94204
        KWIL
        Participant
          @kwil

          You will need the metric conversion set of change wheels and the metric banjo on which to mount them. When you have set up for a particular metric pitch, whilst you are actually cutting the thread you MUST NOT disengage the clasp nut from the leadscrew which is still imperial. If you machine has a norton type gearbox there are other considerations.

          #94205
          JohnF
          Participant
            @johnf59703

            Dear Chris,

            I have just read your thread on the ML7 and most of what has been said there applies to your S7 however personally I would not bother converting. But if you do I think the DRO is the way to go and there are plenty people who have done this and very successfully.

            I've been cutting metal for over 50 years now and everything I own is imperial and the "on board" computer was programmed in imperial, it even has to do a quick computation of anything metric to give a meaningful value. I realise the younger generation will be all metric and wonder what inches are but for me I will stick to that which I understand. If I get a metric drawing a few moments on the calculator and I have all the dimensions in imperial–Oh joy smiley

            Regarding screw cutting, I think you said you have a QC gearbox on the S7 ? If so to cut metric you will need to buy the kit from Myford which consists of a new quadrant and some additional change wheels —will have to look at mine to see which ones. This will allow you to cut a range of metric pitches just by changing the levers on your QC box but you will have to leave the clasp nut engaged for the duration of the operation and reverse the lathe back to the start point after each cut.

            There are several cleaver devices that have been designed to overcome this if you want to cut a lot of metric it will be worth considering building one. look at "screw cutting made easy" on this site.

            I also have an Emco Maximat and the conversion for metric threads is much easier on this machine so if I REALLY have to cut metric this where I do it now.

            Wishing you success in your endeavours whatever you decide to do.

            Regards John

            PS where are you located? I am in Lancashire

            #94208
            John Haine
            Participant
              @johnhaine32865

              What do you want to do? As I pointed out before many metric pitches can be approximated quite accurately enough for fasteners with appropriate change ratios and the 8 tpi leadscrew. Only if you want to make a measuring screw will you really need a 127 tooth wheel in the train. Or you could go the ELS route as described by Tony Jeffree in MEW or even cnc the z axis.

              #94212
              ASF
              Participant
                @asf

                If you read this post **LINK**, you will see that a good way around screw cutting is shown.

                I have these gears for my S7 (with gearbox). It will not be 100% accurate but will be a very good approximation on most of the most common threads. You get a chart with them to show what gear goes with what thread

                #94214
                chris j
                Participant
                  @chrisj

                  Here is a picture of my gearbox, not sure what type it is.

                  gearbox.jpg

                  #94215
                  chris j
                  Participant
                    @chrisj

                    I couldn't find the "screw cutting made easy" sadly, brain issue probably. smiley

                    I'm slowly coming around to the idea that I should leave the lathe alone and work around it.

                    I do fancy putting some magnetic DRO's on the top slides.

                    Thanks for the advice guys, it's slow to go in but I'm getting there.

                    #94219
                    JohnF
                    Participant
                      @johnf59703

                      Hi Chris,

                      Sorry my error it should have been screwcutting simplified — look at this link

                      **LINK**

                      Your gearbox is the standard Myford Quick Change box or a Norton box in engineering parley

                      Regards John

                      #94220
                      chris j
                      Participant
                        @chrisj
                        Posted by JohnF on 11/07/2012 22:07:15:

                        Hi Chris,

                        Sorry my error it should have been screwcutting simplified — look at this link

                        **LINK**

                        Your gearbox is the standard Myford Quick Change box or a Norton box in engineering parley

                        Regards John

                        Brilliant thanks.

                        I'm in Great Yarmouth by the way.

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