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New powerfeed for lathe - DC variable speed

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  • New powerfeed for lathe - DC variable speed

    My import 12x36 is an older belt drive with the open gears on the far left end and open style quick change gearbox. When using the power feed at anything above threading speeds it makes a lot of noise and a lot of the moving pieces are just on bronze bushings. I'd seen one other person with a very similar lathe adapt a DC motor to the feed rod so I decided to do the same. The results are blissfully quiet power feed and a lot of wear and tear saved on the gear end. Also on the fly feed rate changes. The only downside now is I have no idea what my feed rates actually are, but in the little bit I used it today getting it up and running I'm not missing that.

    The motor is a power seat motor available on amazon for $17 and the speed control is a 15A model also from amazon. I installed a DPDT switch to give me fwd/rev/stop. The chain and sprockets are #25 from surplus center, tiny little things. Running it for now on a extra car battery I had kicking around as I heard these controllers don't necessarily like switching power supplies. The top speed is about perfect and I'm getting wonderful surface finishes when dialed down. I'm going to use the same motor/control for a power feed for my mill, but I'll be running off 18V LiIon cordless tool batteries for more speed.


    Last edited by JCByrd24; 04-24-2018, 05:31 PM.

  • #2
    I run anything and everything off switching supplies, I've never had an issue and don't recall hearing anyone else having issues either.

    I really like the idea of tossing the change gears for a motor. If a stepper was used, its halfway to a pseudo-CNC

    Sent from my SM-G930W8 using Tapatalk

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    • #3
      Nice job. I suppose you'd eventually want to enclose the chain pretty well.

      Once you get your power supply setup you could carefully measure how long it takes to feed a longer distance and then calibrate the knob. You might also find that a replacing the pot with one tuned specific to your application would allow you to use the full range on the knob and accurately choose a feed.

      Or maybe you'll just calibrate via voltage? Once you have the volts vs feed factor figured out, a scaled display would display feed directly. Does it slow down much under load?

      Comment


      • #4
        As that is not a motor that can be CNC'd easily, and you DO have the QCB, I am not sure what the real advantage is. Noise, OK, but not being able to know the feed would be a non-starter for me.

        it seems you should be able to know, at least roughly. I assume the readout gives voltage. If so, you should be able to time a certain distance, and get speeds for various voltages. Then, a table of voltage vs spindle speed could be made that would give a decent indication of feed per turn. A bit of fun with MS Excel.

        The load applied would probably affect the speed a bit, but snce that is a gearmotor, and the feed loads are not usually heavy in finishing cuts, I would think you could do pretty well in terms of accuracy.

        I see that two of us had the same idea and were typing at about the same time.
        2730

        Keep eye on ball.
        Hashim Khan

        Everything not impossible is compulsory

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        • #5
          Nice work. Consider having the on/off switch on your carriage. If you are working close to the chuck it's a way to reach for the feed switch especially if you have a small landing zone.

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          • #6
            Nice, clean install. Don't worry about not knowing the feed rate. I never look at the numbers, I just know from experience where to position the QCB levers to get what I want, and after a few hours playing with your setup, you'll know where to set the knob. I personally don't think totally enclosing the chain is important, but I would do a half-cover that would deflect debris from the top and inside.
            Southwest Utah

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            • #7
              Yep... I also have no idea or really care about actual "number". I have levers for 32 (?) feed combinations. I use maybe 4 of them. Of course, mine are "in/rev" and this is now independent of spindle, but you will quickly figure what you need for your usual tooling/speeds. As for "cover", how much debris is going to get on it at the tail stock end anyhow?

              I use that same PWM controller for high power LED dimmers.
              Last edited by lakeside53; 04-15-2018, 11:54 AM.

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              • #8
                If you fitted a switch on the left hand end of the apron, with an adjustable collar on the feed rod, you could set it to stop at a predetermined point.

                Comment


                • #9
                  Originally posted by Robin R View Post
                  If you fitted a switch on the left hand end of the apron, with an adjustable collar on the feed rod, you could set it to stop at a predetermined point.

                  Dang, I like that!
                  Southwest Utah

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                  • #10
                    Also .. on my lathe if you find that your not happy with the speed you have selected, you
                    have to stop the lathe to change it. With your's, you can fine tune it on the fly, sounds
                    like an advantage to me.
                    John Titor, when are you.

                    Comment


                    • #11
                      DC motor feed drive was good enough for Hardinge HLV.

                      Comment


                      • #12
                        This is positively a fantastic new toy ! ! ! !

                        I've got the same issue with my own lathe. Like yours it is a belt driven headstock and at any but the lowest speeds the gearing in the back cover howls like a bad tire at freeway speeds. As a result I've only used the power feeds sparsely over the whole time I've had the lathe. I'd rather do a 3 or even 4 inch feed by hand than put up with the noise when running higher speeds for aluminium and the like.

                        I'd never thought about some of the automotive motors but something like that power seat motor is pretty well perfect for size and they must be pretty strong due to the big butts they have to push back and forth.

                        Like you I'm also looking for an option on the mill's table. I cringe at the prices they want for a power feed.

                        I can't see the lack of a fixed feed number being an issue either since I've always picked the speeds I use by eye anyway. And clearly I don't really have a clue about what the feed rate is when doing it by hand other than I aim for a "happy chip" with a suitable for the job surface finish. So just use the speed dial a lot to start slow and ramp it up.

                        I really like the idea of the automatic stop. I also just went out to the lathe and I'm thinking I might further remove and remote the direction switch and speed dial to a small remote box that attaches to the carriage apron. I'm just not quite sure exactly where because my lathe has a third control rod for the apron mounted start and stop.
                        Chilliwack BC, Canada

                        Comment


                        • #13
                          If you don't care about the surface finish, then not knowing is OK. It can be very handy to know, and of course with the QCB you DO know.

                          And, in this case, it should be really easy to come up with figures for a half dozen (at most) feeds for different materials and finish requirements. No reason not to. I have considered the same thing for the Logan, which is a change gear machine, and would benefit from a separate feed just to cut the number of gear swaps.

                          But I have not done it yet. Reason being that I have the lower model, without a power feed for turning. Just uses the half nuts, which I prefer not to do, since I put a new leadscrew on a while back. The old one was worn to a nubbin due to being used for feed.

                          So if I do add a feed like that, it will be required to operate directly on the handwheel, and not through the leadscrew.
                          2730

                          Keep eye on ball.
                          Hashim Khan

                          Everything not impossible is compulsory

                          Comment


                          • #14
                            Originally posted by BCRider View Post
                            This is positively a fantastic new toy ! ! ! !

                            I've got the same issue with my own lathe. Like yours it is a belt driven headstock and at any but the lowest speeds the gearing in the back cover howls like a bad tire at freeway speeds. As a result I've only used the power feeds sparsely over the whole time I've had the lathe. I'd rather do a 3 or even 4 inch feed by hand than put up with the noise when running higher speeds for aluminium and the like.

                            I'd never thought about some of the automotive motors but something like that power seat motor is pretty well perfect for size and they must be pretty strong due to the big butts they have to push back and forth.

                            Like you I'm also looking for an option on the mill's table. I cringe at the prices they want for a power feed.

                            I can't see the lack of a fixed feed number being an issue either since I've always picked the speeds I use by eye anyway. And clearly I don't really have a clue about what the feed rate is when doing it by hand other than I aim for a "happy chip" with a suitable for the job surface finish. So just use the speed dial a lot to start slow and ramp it up.

                            I really like the idea of the automatic stop. I also just went out to the lathe and I'm thinking I might further remove and remote the direction switch and speed dial to a small remote box that attaches to the carriage apron. I'm just not quite sure exactly where because my lathe has a third control rod for the apron mounted start and stop.
                            Hi,

                            Go to monsterguts.com, order a 2 speed 12VDC wiper motor, head over to eBay and order a 6A power supply for less than $10, PWM for less than $10, same for a DPDT switch. Build a box and adapter to drive your lead screw. You now have a $300+ power feed for less than $40.

                            This will also work for a lathe. If not knowing exactly how many inches per minute your mill feed is running is no big, why would it bother anyone to know about exactly what inch/rev a plain lathe feed is doing?
                            If you think you understand what is going on, you haven't been paying attention.

                            Comment


                            • #15
                              Originally posted by dalee100 View Post
                              ....
                              This will also work for a lathe. If not knowing exactly how many inches per minute your mill feed is running is no big, why would it bother anyone to know about exactly what inch/rev a plain lathe feed is doing?
                              It DOES give the cut per tooth on the mill, which can be quite useful to know.

                              On the lathe, it will again tell you the chipload, and will help when wanting fine finishes.

                              Can you "by guess and by golly" that stuff? Sure, you certainly CAN. Sometimes it does lots better if you use at least a decent stab at good numbers
                              2730

                              Keep eye on ball.
                              Hashim Khan

                              Everything not impossible is compulsory

                              Comment

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