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Got my Orac CNC lathe, now an electrical question.

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  • Got my Orac CNC lathe, now an electrical question.

    Finally got the little Denford ORAC CNC lathe safe & sound; thanks G. Maxton and Estes Express! S-m-o-o-t-h ballscrews w/double preloaded nuts & double angular contact brgs at each end, like-new ways & spindle bearings and the paint looks good enough for me; just needs a good cleaning. Man, my inner nerd is ecstatic. Almost had to go smoke an after-sex cigarette (I quit smoking 27 yrs ago) and rest a while after looking it over.

    It has no electrical equipment at all (other than the audio cassette player ) so I'll be installing the stuff I've been accumulating. I have 2 nice stepper motors (thanks Sparky!), a controller & 28V transformer to power it (has an on-board power supply), a KBIC-120 speed control, a 3/4 hp 90V DC motor (hopefully I'll get the Baldor I'm watching on eBay, if not, I'll get a chinese Leeson knock-off), a spindle speed sensor/board from CNC4PC, I'll probably get his C11 opto isolated BOB/speed control/relay board as well along with various switches, fans, an emergency stop button, etc.

    All this stuff has to have various power feeds: 115V AC, 12V DC, 5V DC, etc. I want to keep it simple so was thinking I could feed a nice big power strip with a contactor switched on by some type of lift-the-top-up toggle safety switch with the big red emergency stop button between it and the contactor. I'd plug in the various wall warts and the transformer to the power strip and be good to go. It will have no sliding doors with guard switches, seat belts, air bags, 5 mph bumpers or other such stuff.

    Can it be this electrically simple and still be reasonably safe? I should know this but my electrical knowledge is mostly DC automotive so ya'll be nice.
    Milton

    "Accuracy is the sum total of your compensating mistakes."

    "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

  • #2
    Milton.

    GO AWAY don't start.

    Just got a nice clean floor and a pristine ORAC in storage and I don't want any more projects just now.

    There was an article in MEW a couple of years ago on doing one of these, I'll look it out for you, want to PM me an email address ?
    .

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



    Comment


    • #3
      This one needs a mate John.

      edit: missed your offer, yes please do!
      Milton

      "Accuracy is the sum total of your compensating mistakes."

      "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

      Comment


      • #4
        Originally posted by John Stevenson
        There was an article in MEW a couple of years ago on doing one of these, I'll look it out for you, want to PM me an email address ?
        PM sent, thanks!
        Milton

        "Accuracy is the sum total of your compensating mistakes."

        "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

        Comment


        • #5
          Ok, found the article quite easily. Should be with you by now.
          .

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



          Comment


          • #6
            Great article John thanks. I'd already been thinking about how to do up a longer cross slide and Bada-Bing, there's one already done in the article!
            Milton

            "Accuracy is the sum total of your compensating mistakes."

            "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

            Comment


            • #7
              I dare not read the article.
              However it's now got me wondering as I can't remember where I stored this machine . Need to make some phone calls on Monday.

              According to small son we have 12 small mills or lathes in the wings waiting for transplants. Need to do a head count.
              .

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



              Comment


              • #8
                I did an ORAC some years ago - I stripped everything out of the plinth and fitted a small form factor Compac pc inside with a home made simple power supply and Gecko stepper drivers. Made a new hinge down front panel incorporating one of those waterproof 'roll up' keyboards. Mine still had the original steppers which were fine, also the spindle encoder. I managed to get a tool turret for it, and with a bit of custom electronics was able to tool change by G code. Finished it, got it fully working and realised it was too small for my stuff so sold it!

                Comment


                • #9
                  I've seen references to your ORAC here & there on the web Andrew during my frenzy to gather information while waiting for it to arrive. You did a great job on yours; I hope mine comes out somewhere near as nice.

                  Do you think my contactor/powerstrip rig will work OK?
                  Milton

                  "Accuracy is the sum total of your compensating mistakes."

                  "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

                  Comment


                  • #10
                    Dont do the power strip thing.

                    You can get one switching power supply that will supply virtually all the low voltages.

                    Just use DIN rail mounted terminal strips to split incoming and outgoing power. Much cleaner.

                    Comment


                    • #11
                      I have been using one of these disk drive supplys in my retrofits. They output 12V and 5V at 2 amps each. Input is 90-250 Volts. Small, cheap and easy.

                      http://www.ebay.com/itm/12V-5V-AC-Ad...item35b1f050d5

                      Comment


                      • #12
                        look on youtube

                        theres a few there ..

                        including a BBC " william woodward" one from the 80's

                        all the best.markj

                        Comment


                        • #13
                          Originally posted by John Stevenson
                          However it's now got me wondering as I can't remember where I stored this machine
                          Hope you didn't leave it in the old Donald

                          Dave
                          Just south of Sudspumpwater UK

                          Comment


                          • #14
                            Originally posted by macona
                            Just use DIN rail mounted terminal strips to split incoming and outgoing power. Much cleaner.
                            Ahh, so that's what you call that system. There's one in my Denford mill and I just thought it was a really neat setup they came up with. Didn't have a clue it's a universal system and readily available on eBay until you mentioned it and I did a search, thanks! You guys will edumacate me yet!

                            Thanks for the link George, that's certainly a great price. Cheaper than a handful of wall warts for sure.

                            Now back to my original question. Should the the mains power come through a contactor with the emergency stop button rigged to turn it off and kill everything at once? My Denford has the DIN terminal strip with several fuses and relays. I'd rather have one big shutoff rather than several relays.
                            Milton

                            "Accuracy is the sum total of your compensating mistakes."

                            "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

                            Comment


                            • #15
                              Originally posted by Sparky_NY
                              I have been using one of these disk drive supplys in my retrofits. They output 12V and 5V at 2 amps each. Input is 90-250 Volts. Small, cheap and easy.

                              http://www.ebay.com/itm/12V-5V-AC-Ad...item35b1f050d5
                              That is the style of power supply, at a comparable price, you expect to be shipped with usb to sata/ide adapters. I looked at a bunch of those on newegg and dealextreme a while back. There were an alarming number of customer reviews reporting that the power supplies fried the user's hard drive. So be cautious. Hard drive power supplies can be quite useful for homebrew projects and these external modules seem to be a lot easier to come by now than the bare boards (external hard drive cases having devolved to use external power supplies).

                              There are a lot of closed frame, open frame, and din rail mount power supplies out there in single or multiple voltage outputs - with screw terminals for input and output which are useful if you are trying to do a fairly professional wiring job. Here is an example of some DIN rail mount supplies. There are a bunch on ebay as well.

                              http://www.automationdirect.com/adc/...FQaEnQodlkiVjw

                              You can also use step down dc-dc converter modules to make 5V and 12V from your 28V motor power. Note that some look a bit too cheap. See my comments on power supply reliability in the microwave oven thread.

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