Announcement

Collapse
No announcement yet.

Turret Lathe Question Thread

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Turret Lathe Question Thread

    After quite some time keeping my eyes open I finally found a turret that I can fit to my Ames lathe. This is something that I have wanted for quite some time, I had hoped to find an original Ames turret but they're pretty rare and this one popped up and I've decided to make it work.





    It is a Derbyshire turret, off of one of their later model lathes, and since the seller did not know that I got it for a very fair price. The turret is in good shape, operates tight and smooth, and shows very little wear on the sliding surfaces. There is one clamp missing and the pivot pin for the lever was non-original, so I emailed the contact on Derbyshire's website asking if they still support these turrets and if they had any spare parts. Low and behold, they do and he sent me a complete parts diagram and their prices for the parts are very reasonable so I will be getting some replacements through them. Fantastic service from a 110 year old company, above and beyond answering questions I had and providing information to me. Very happy with that experience.

    I will need to make (or have made) an adapter to mount this turret on my lathe. The Ames has a 8 3/8" swing, the Derbyshire has a 75mm center height, so that will be a matter of making a plate with matching profiles of the Derbyshire bed on the top and the Ames bed on the bottom. They're simple beds so with the right equipment that shouldn't be to big of a deal.

    As of now I'm working out what tooling I will need for the work I want to do. The turret takes 5/8" tooling, so finding it should not be a problem. I've got most of it figured out, but there is one operation on my parts that I need some advice on.



    If you look at those parts there is a very slight (2-3 degree) taper that feathers down to the hole drilled in the part. What is the best way to make that taper using a turret? I realize that I could do it using my cross slide, but I need my cross slide for parting off pieces. Is there any sort of tooling that can be run off the turret to make a taper like this? Should I look at a form tool with a back rest?

    TIA
    Cayuga, Ontario, Canada

  • #2
    Form tool with a back rest might work. Maybe a multi edge tool that looks like an inverted countersink would be better. Are you starting off with solid bar? What are the dimensions of the part, material, and what's your expectation for surface finish?

    Comment


    • #3
      I would check the turret bores to see if they are true to your lathe. Sometimes the bores are off and you need to rebore to a bigger bore size to true them to your lathe. I think I would adapt a box tool type tool with the rollers on od of material to try to form that taper because of chatter. It’s hard to tell what size material and hole size from your pic. Also may work better if you form tapered od before drilling bore.
      Jim

      Comment


      • #4
        Length of the taper ranges from 3/16" to 7/16", diameter before turning from .195 to .350. Material will be 18% Nickel Silver and bronze alloys (not sure if I'll go with 954 or 642). Surface finish needs to be good.
        Cayuga, Ontario, Canada

        Comment


        • #5
          There are turret tools that will follow a template. That would seem ideal for your taper.

          I have many duplicate turret tools from Doc's treasure trove, and some may be of that type. I will look and see if I have anything suitable. If so, you can have one for postage.

          Don't get excited until I check.

          Yes, I do have multiples of this type

          Last edited by J Tiers; 04-26-2021, 11:03 PM.
          CNC machines only go through the motions

          Comment


          • #6
            Do you have a production cross slide with a tool post in the rear? Form taper in front cut off in back.
            Jim

            Comment


            • #7
              Originally posted by jimsehr View Post
              Do you have a production cross slide with a tool post in the rear? Form taper in front cut off in back.
              Jim
              I like this option. Otherwise I think you're almost looking for an OD reaming setup. And while certainly possible it won't be easy. Even if you can find a lot of regular turret tooling this would be something that is above and beyond I'm thinking and require a custom approach. Not impossible by any stretch. But it won't be an off the shelf item.
              Chilliwack BC, Canada

              Comment


              • #8
                Okay, according to several books I have, there's a few ways to do it.

                One, as noted, a form tool. I can't say how nickel-silver turns, or know what kind of surface finishes you're after, but those tubes look a little thin to try that wide a form tool. A form tool can attach to the cross slide or to the turret- a tool in the turret works kind of like a pencil sharpener.

                Two, a taper attachment. Many turret lathes have a surprisingly conventional turret attachment available for either the carriage or even the turret itself. (Though that latter is usually reserved for the bigger machines with a saddle-mounted turret.)

                And three, a trick noted in a 1917 Coventry book, is a sliding tool attached to the turret, and which has a wheel or hardened pin. When rotated into place, that pin contacts a wedge bolted to the bed, or cross slide or overhead bar, etc. and when advanced, forces the cutter to move at an angle.

                I've seen probably six or seven different versions of that trick, and if I had a large number of parts to produce, is probably the way I'd do it.

                Barring that, the fourth trick is to have a small lever slide attached to the cross slide, that when actuated produces the taper. As noted above, if you're doing something else with the cross slide, mount it behind the work. If I needed to make a relative few parts, this is how I'd go. A small slice could probably be fabbed from a cheap surplus compound.

                Or, there's this trick I keep hearing a lot about, where you can actually bolt a computer to your lathe, and...

                Doc.
                Doc's Machine. (Probably not what you expect.)

                Comment


                • #9
                  Thanks for the advice. I do not have a production cross slide, but I think that may be the best way to go. I know that Hardinge made a little lever slide like Doc mentioned that could be a good solution, rather than trying to form the surface. Nickel silver isn't a tough material by any means, but from what I understand the bronze can be, and I think that using a form tool might be asking for trouble with the thin walls (either tearing if I drill before forming, or any sort of chatter causing my thin rear edge to get damaged if I drill after forming). I production set-up with a tool following a profile is not going to be flexible enough for my needs, great for really large runs but I'm looking more at smaller runs using the same setup of tools.

                  Time to see what I can hunt down.
                  Cayuga, Ontario, Canada

                  Comment


                  • #10
                    Originally posted by Doc Nickel View Post
                    Or, there's this trick I keep hearing a lot about, where you can actually bolt a computer to your lathe, and...
                    What are these computer things you speak of? I like gears, knobs, levers, and linkages.
                    Cayuga, Ontario, Canada

                    Comment


                    • #11
                      Usually done with a turret lathe swing tool and adjustable guide.
                      W&S has two tools that would do the same task. Dedicated taper turner, M1816, M1818 and Taper forming box tool,M927, etc.
                      Last edited by reggie_obe; 04-23-2021, 11:54 AM.

                      Comment


                      • #12
                        Just a thought but I think it would result in minimal tooling to be made up and might even be useful for a wide range of work.

                        Make up a rack for your compound that allows you to set it up with a 1 or 2 inch travel dial gauge. Then provided you have a QCTP that can swap holders without losing registration you can use the compound for the taper and return it to the same starting point each time and swap cutters all without losing your registration for each operation. This would be something that might be handy on the bed too. Or do something much the same but instead of a dial gauge where you have to write down numbers and remember than make up a little 4 position stop rod setup.

                        I think I'd prefer the dial gauge though because it can reference in both directions. And if we have to focus for long enough to remember or reference the number perhaps we won't forget to turn the indexing stop....

                        The reason I like the dial gauge is that it neatly steps around the issue of play in the screw and nut and the small 10ths dial keeps us in tune with the distance along the inch or two of travel.

                        It's also possible that you could do this with one of those "half a computers" in the form of a cheap stand alone digital linear scales. I don't know if they make 3 inch versions though. I think 6 inch is as small as they go.
                        Chilliwack BC, Canada

                        Comment


                        • #13
                          Fly rod ferrules? Make a form tool for the turret. It's been done before.

                          Comment


                          • #14
                            Skive tool, do it in one shot.
                            https://www.productionmachining.com/...art-of-skiving

                            Comment


                            • #15
                              Because you are not well tooled, consider this....it will get you in production.
                              do all you can on the turret...except the taper.
                              then set your compound at correct angle, mount pieces in chuck or collet... and machine taper as a second op..
                              then you can start building taper slide and what not for the turret..

                              Comment

                              Working...
                              X