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  • Variable Speed on lathe lead screw

    I have a Craftex B2227L lathe and I'm interested in mounting a treadmill motor (I have a 2.25 hp one with all controls) on the lead screw so I don't have to use the change gears for various feed rates unless I am cutting single point threads.

    Does anyone have any experience with doing this? Can it be run slow enough for fine finish? Pictures of setups? Words of wisdom/warning? Or should I just suck it up and get practice in changing gears all the time?

    If possible I would like to leave the graduated collar and hand crank on in case I want to do precise feeds with the lead screw. Is this asking too much?

    Any thoughts would be appreciated!

    Tom

  • #2
    Rather then modifying an existing machine why not obtain a machine that has the simple features that you require?
    In 40 years I have never used a lathe that did not have a gearbox for feed rates.
    This Craftex lathe looks like it has all the requisite knobs and levers that do not require change gears.

    Comment


    • #3
      I put a DC servo drive on my Jet 1024 feed shaft & I wouldn't have it any other way. The Jet has a threading shaft and a feed shaft, so it's a bit different from yours. Anyhow, here's its story:
      https://drive.google.com/file/d/1R8I...ew?usp=sharing

      There is a gotcha on having a control calibrated for feed - i.e., advance per spindle revolution. The controller needs to know the spindle rpm. Or you could just have an uncalibrated control and dial in what works.

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      • #4
        Hardinge Lathes have that feature ( DC Motor, and varispeed option to drive the carriage )
        Rich
        Green Bay, WI

        Comment


        • #5
          that'd be neat, but I wouldn't use a treadmill motor - too big and too fast. A small 24V DC motor, maybe even a gear motor, would give you enough umph and speed range. Plus there are plenty of small PWM based speed controllers for them.

          Comment


          • #6
            Thanks for the information!

            Bented: While it would be nice to just buy the lathe that I really wanted, living on the edge of civilization means used machines are few and far between without hours and hours of driving - and that's been tough to do for the last year or so. (I just bought this lathe locally a couple of months ago) Also, I have limited funds to work with. And I enjoy modifying!

            Bob - I look forward to seeing what you did. From what you and Matthemuppet have said, sounds like the treadmill motor won't work. Too bad. Nice speed controls and great price (free).

            I'll see what I can find out about a DC motor with variable speeds. Always nice to have a project to work toward. Just not a fan of inventing a wheel that many people have already found out doesn't work.

            Thanks all - I appreciate you taking the time to give suggestions/advice.

            Comment


            • #7
              You're thinking about an Electronic Leadscrew, commonly known as an ELS. There are quite a few developed systems out there. Just search for "lathe ELS".

              Comment


              • #8
                Originally posted by Tomc938 View Post
                Thanks for the information!

                Bented: While it would be nice to just buy the lathe that I really wanted, living on the edge of civilization means used machines are few and far between without hours and hours of driving - and that's been tough to do for the last year or so. (I just bought this lathe locally a couple of months ago) Also, I have limited funds to work with. And I enjoy modifying!

                Bob - I look forward to seeing what you did. From what you and Matthemuppet have said, sounds like the treadmill motor won't work. Too bad. Nice speed controls and great price (free).

                I'll see what I can find out about a DC motor with variable speeds. Always nice to have a project to work toward. Just not a fan of inventing a wheel that many people have already found out doesn't work.

                Thanks all - I appreciate you taking the time to give suggestions/advice.
                I'm still a bit confused. That lathe has about as modern of a QCGB as they come, they change as fast as could be. I'm not sure how one could want anything more unless he/she was doing serious, serious production work.
                21" Royersford Excelsior CamelBack Drillpress Restoration
                1943 Sidney 16x54 Lathe Restoration

                Comment


                • #9
                  1. being able to dial in the exact feed you want, rather than going with whatever setting the gear box provides
                  2. being able to vary feed in the middle of a cut based on chatter, chip production etc
                  3. less noise as the gear train can be disconnected

                  those are what I can think of off the top of my head

                  to Tom, treadmill motors make great spindle motors (putting together a drive right now) but their 4000rpm top speed means you really need a countershaft to step the spindle speed down to a useable range.
                  Last edited by mattthemuppet; 04-28-2021, 08:42 PM.

                  Comment


                  • #10
                    Originally posted by mattthemuppet View Post
                    1. being able to dial in the exact feed you want, rather than going with whatever setting the gear box provides
                    2. being able to vary feed based on chatter, chip production etc
                    3. less noise as the gear train can be disconnected

                    those are what I can think of off the top of my head
                    1. Generally they are settable to within 1 thou feed rates, at least for normal rates. If that isn't enough to make one happy, they may just not be a happy person.
                    2. Again, takes only a second to stop the cut and twist the tumbler.
                    3. Modern oilbath QCGB are pretty quiet.
                    But yeah, I get your point. For me personally, there is about 1 million other shop projects/upgrades I would take on before an electronic feed rod.
                    21" Royersford Excelsior CamelBack Drillpress Restoration
                    1943 Sidney 16x54 Lathe Restoration

                    Comment


                    • #11
                      Originally posted by Bented View Post
                      Rather then modifying an existing machine why not obtain a machine that has the simple features that you require?
                      In 40 years I have never used a lathe that did not have a gearbox for feed rates.
                      This Craftex lathe looks like it has all the requisite knobs and levers that do not require change gears.
                      Why is the solution to any question on Home Shop Machinist always "go out and spend $5000 on a new machine", rather than any solutions that actually address the questions asked? Seriously, people wonder why post count is down, its almost like the home shop people who show up get discouraged thinking they dont have enough money to bother with the hobby...

                      Addressing the actual question asked, Tom, ive messed around with driving the leadscrew with its own motor. In my case i wanted feed rates slower than what i could get with the gears on my lathe alone. Honestly, too much trouble for me, since with the leadscrew decoupled from the workpiece feedrate changed drastically if i varied the cut speed at all, not to mention getting a motor with usable torque throughout the speed range i needed for my lathe was pretty much impossible (Small lathe, fast spindle speeds, 16tpi leadscrew). Im looking into building an electronic leadscrew now, whenever i get around to it. All the convenience of changing feeds at the touch of a button with relatively minimal work, compared to finding a way to add a gearbox. Ive been followiung this dudes build, he goes through pretty much everything and sells the parts that you need, plus the entire project is pretty easily modifiable to fit pretty much any lathe: https://www.youtube.com/watch?v=FTs9GygRQ-U

                      Plus, i save five grand by not buying a new lathe

                      Comment


                      • #12
                        Originally posted by Tomc938 View Post
                        I have a Craftex B2227L lathe and I'm interested in mounting a treadmill motor (I have a 2.25 hp one with all controls) on the lead screw so I don't have to use the change gears for various feed rates unless I am cutting single point threads.

                        Does anyone have any experience with doing this? Can it be run slow enough for fine finish? Pictures of setups? Words of wisdom/warning? Or should I just suck it up and get practice in changing gears all the time?

                        If possible I would like to leave the graduated collar and hand crank on in case I want to do precise feeds with the lead screw. Is this asking too much?

                        Any thoughts would be appreciated!

                        Tom
                        First, welcome to the forum.

                        From my experience you don't always need that graduated collar and dial. It's great for feeding the carriage a specific amount, but with the dial down at the tailstock end of the machine it's awkward to use. Better off fabricating an indicator holder that clamps to the front v-way. I've been doing it that way for years. As for power feed, maybe you can retrofit the power feed off a milling machine X or Y axis drive. The most popular (read: expensive) is the Servo brand, but there are cheaper knock offs, and different designs that might be a good starting point.

                        Comment


                        • #13
                          Metal Butcher: (love the name, BTW). I think you are perhaps confusing the lathe I have (picture below) with the picture posted by Bented. A QCGB would be the quickest and easiest way to go. That was just part of my original wish list (along with power cross feed) but after looking for about 6 months I reduced my expectations. Once I have a few years experience, and the plague is over so I can access larger centres, those two things are still on my wish list. For now I glad I can make large round stock into very fine swarf. ;o)

                          Click image for larger version

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                          • #14
                            Originally posted by Tomc938 View Post
                            I have a Craftex B2227L lathe and I'm interested in mounting a treadmill motor (I have a 2.25 hp one with all controls) on the lead screw so I don't have to use the change gears for various feed rates unless I am cutting single point threads.

                            Does anyone have any experience with doing this? Can it be run slow enough for fine finish? Pictures of setups? Words of wisdom/warning? Or should I just suck it up and get practice in changing gears all the time?

                            If possible I would like to leave the graduated collar and hand crank on in case I want to do precise feeds with the lead screw. Is this asking too much?

                            Any thoughts would be appreciated!

                            Tom
                            Originally posted by The Metal Butcher View Post

                            I'm still a bit confused. That lathe has about as modern of a QCGB as they come, they change as fast as could be. I'm not sure how one could want anything more unless he/she was doing serious, serious production work.
                            Is this the lathe you are using? If so, it only has change gears, not a QCGB, which might be leading to some confusion here:

                            https://www.busybeetools.com/content...als/B2227L.pdf

                            Comment


                            • #15
                              Originally posted by epicfail48 View Post

                              Why is the solution to any question on Home Shop Machinist always "go out and spend $5000 on a new machine", rather than any solutions that actually address the questions asked? Seriously, people wonder why post count is down, its almost like the home shop people who show up get discouraged thinking they dont have enough money to bother with the hobby...
                              I have been buying AND SELLING machines for years.
                              Upgrading to better machines and making money selling
                              the ones I grew out of. So............Yes go out and spend
                              $5000 on a new machine. And sell the old one, make
                              some money back and UPGRADE.

                              --Doozer
                              DZER

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