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  • #31
    Tailstock Design Part 3

    Using the lever and handwheel adds the original screw travel to the setup.




    Once the screw is right in the handwheel can then be deployed.



    In this case giving a massive 6" of travel but with the barrel / barrel extension fully supported. Chances are you would not use this travel but it's nice to know it's there if need for say deep hole drilling.

    The Chinese ones can be done exactly the same way and I have one here but because of a conflict of interests I can't post those pictures.

    One problem that still exists is the play in the barrel that I addressed in my other post on tailstocks and by designing a new keyway system that can also be rectified.
    I have also come up with a sealing system that will double up to reduce wear and play but again that I can't mention but there are many many ways to achieve the same aims.

    End of post.

    .
    .

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



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    • #32
      That is pushing the length to diameter stiffness ratio, just a tad

      But the travel is welcome in many applications...

      My old SB with a wrench operated tailstock to bed clamp, and short quill travel... has eaten up a few hours of deep hole drilling time..

      My bigger lathe has not limited me much yet... but will someday..
      Last edited by Bguns; 11-08-2009, 08:00 AM.

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      • #33
        Btw dockrat, Why do you need a center on such short parts?
        The quill need not reach all of the way over the apron as short workpieces do not usually need its support. This inability is of course a hallmark of a cheap machine, as you must be aware since you probably bought it for that reason.. So what's to complain about?
        Aside from the un-called-for slam against the OP in the second quote, you guys aren't thinking outside the box here.

        Not ONLY does teh carriage/crosslide need to FIT under the tailstock ram, it would be nice if the carriage was actually USEFUL under there.... instead of just sitting there looking pretty. That means you want to have some carriage travel.

        And then also you might someday want to actually turn a feature on the part which is close to the tailstock end. You may not have much travel towards the headstock either.

        In the picture of the short ram, the carriage is not movable closer to the tailstock, so unless you can use the topside as a substitute workaround for longitudinal movement, you can't do the job that way.

        If you happen to be turning a taper on part of the work, and straight portions on the rest, you might be doing a lot of taking off, resetting, putting back and continuing work. With a sensible tailstock-to-crosslide width ratio, that would not be necessary.

        Or in some cases the topslide feed handles may graze or interfere with the tailstock when trying to get the topslide parallel to the axis for use as a substitute workaround feed.

        That all-purpose wide crosslide was probably designed for milling, but causes some severe compromises.

        On lathes designed for lathe work, without extra features, the carriage is purposely made narrow in the middle, specifically so that you WILL be able to actually use the carriage feed when working on small parts between centers. it also means that a sensible tailstock ram travel can be used and be quite functional.


        Finally, length is relative.

        if your part is 1.5" long, but 0.156 diameter or maybe smaller in places, you can't really expect to stick it out of the chuck and do work. You are going to use centers.

        Originally posted by Robin R
        It sounds like J Tiers is describing a bed turret, see the second picture from the bottom. http://www.lathes.co.uk/hardinge/page4.html

        Not really, I have a bed turret, they are totally different animals. but the design approach would work OK.
        1601

        Keep eye on ball.
        Hashim Khan

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        • #34
          Originally posted by dp
          Quill, barrel, and ram are common terms and I doubt anyone is confused.
          There are a lot of "common" terms". Being "common" does not make it correct or acceptable.It could be that one of the differences between a HSM and a professional is knowing the terminology.

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          • #35
            J Tiers, the OP refers to the machine as a "Chi com BVB25L" and a "POS".
            He knows what he bought. The question is "Why?". Even a chi com POS is a sizeable investment so why did he buy it if it is so bad?
            However I'm not sure I see the problem here. Why not travel the saddle under the chuck? If it won't fit, get a smaller chuck. Any lathe can be fitted with a chuck so large that it impedes the cross slide travel.

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            • #36
              Originally posted by tdmidget
              There are a lot of "common" terms". Being "common" does not make it correct or acceptable.It could be that one of the differences between a HSM and a professional is knowing the terminology.
              Or it could mean something else, entirely.

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              • #37
                Originally posted by tdmidget
                J Tiers, the OP refers to the machine as a "Chi com BVB25L" and a "POS".
                He knows what he bought. The question is "Why?". Even a chi com POS is a sizeable investment so why did he buy it if it is so bad?
                However I'm not sure I see the problem here. Why not travel the saddle under the chuck? If it won't fit, get a smaller chuck. Any lathe can be fitted with a chuck so large that it impedes the cross slide travel.
                Tdmidget, if you refer back to my original post you will see where I said “As a hobby lathe it is adequate except for the tailstock.” The POS that I was referring to was the tailstock design only. From what I read in the posts in this thread, my cheap Chinese lathe isn’t the only one with this problem. As to why I bought it….at the time I had absolutely no knowledge concerning lathes. It was more a case of what I could fit in the available room. This fit and I have used it to do a lot of stuff and so far I have not had any case where I have not been able to find a work around to overcome its failings. On reading through your posts I can tell that you know everything there is to know about machines and machining so instead of slamming us HSM’ers for our terminology and cheap machines, how about adding some positive input to the question at hand?
                Ernie (VE7ERN)

                May the wind be always at your back

                Comment


                • #38
                  just to make you guys jealous



                  A full 11" of quill travel.
                  OK it's a 19" lathe. but I do have to watch out for compound and tailstock interfering with one another...

                  Tim

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                  • #39
                    Well most of the small import lathes just have not been given much design thought period. Everything is boxy and square. The problem is not really the tailstock. The entire saddle/tailstock relationship is just poorly though out. This effects many of the import machines and not just yours.
                    The saddles on the these machines also do not have long enough "wings", for the lack of a better term. The saddle wings give the saddle much extra bed contact, making for a more solid foundation. Having long saddle wings allows for a narrower cross slide which improves tail stock reach.

                    Also the QCTP's usually reduce tailstock reach as the tool is mounted off to the side which results in the need to move the carriage more to the right.

                    My SB9-



                    My Artisan 11x24-
                    This machine I love. Note the unusual saddle. It has 3 saddle wings due to it's unusual bed ways and excellent tailstock reach. The tailstock slides over the center wing.



                    Steve

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                    • #40
                      ahhh, I see that the BV25 lathe is also sold as a combo machine. That might explain the wide saddle and cross slide. The extra wide cross slide would surely come in handy for milling.

                      Steve

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                      • #41
                        Originally posted by S_J_H
                        ahhh, I see that the BV25 lathe is also sold as a combo machine. That might explain the wide saddle and cross slide. The extra wide cross slide would surely come in handy for milling.

                        Steve
                        At first I thought it WAS a 3 in 1 machine.
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #42
                          Maybe an idea for a group project would be a range of tailstock castings we could buy and then do with what we wish (since we all have our own ideas, just a big block of iron that looks like a tailstock body would likey be best, can bore or dovetail or whatnot ourselfs)

                          I don't exactly wanna modify my existing tailstock to be longer because as is I allready had to take the handle off the handwheel because it limits my bed length as my tailstock hits the wall before it hits the end of the bed :P (Small workshop)
                          But an second extra long/rigid tailstock would be swapable.

                          My lathe for example just uses the single prismatic way and flat way for the tailstock, so milling it for alignment/fit should be easy..
                          Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                          • #43
                            Tailstock castings

                            You might present this problem to Craig Donges over on the PM forum. He's doing some casting work(having it done)
                            Maybe he could do a "series" of castings that would cover a range of lathe sizes that you could order by "length"?

                            Comment


                            • #44
                              Dockrat, pull your panties out of your crack and read my post. If you fit a smaller chuck the saddle can pass under it and your tailstock will be closer.

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                              • #45
                                Originally posted by tdmidget
                                Dockrat, pull your panties out of your crack and read my post. If you fit a smaller chuck the saddle can pass under it and your tailstock will be closer.
                                A smaller chuck isn't going to help me if I am trying to turn 7" OD stock. I can barely hold it with the 5" chuck I have with the jaws sticking out far enough to cause a major crash against the saddle if I ain't paying attention. However even with normal turning where I can get under chuck with the saddle, I can't get back far enough to start a cut as the backside of the saddle is against the tailstock. Hence the need for the adaptor. Here, lemme show you. I just went and took a picture. Note that the "quill" is at full extention, the compound is as far out as it will go without the screw dropping out, but I can't get back far enough to start a cut as the saddle is up hard against the tailstock and ya can see where the cutter is.

                                Ernie (VE7ERN)

                                May the wind be always at your back

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