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  • ................
    Last edited by J Tiers; 01-04-2009, 01:23 AM.
    1601

    Keep eye on ball.
    Hashim Khan

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    • I don't think that this is about being right or wrong, I think this is about is it going to actually work. I went through something similar to this with my dad on the multimachine project (lathe made with old engine blocks) and he ended up going with tapered roller bearings for the spindle. In his case they were domestic automotive wheel spindle bearings (not the junky autozone ones, but domestic bearings from NAPA), and by swapping them around, buying extras and taking the ones back that were really sloppy, he got the spindle runout under .001" (the best that we could measure at the time). I know that Evan can do better than that, the work that he turns out on his SB9 is simply beautiful and shows an amazing attention to detail.

      Another thing that I would seriously look at it using a spindle that is that small on a big swing lathe. From past experience I think that you are going to have enough flex in the spindle to cause chatter when you try to turn larger parts. The spindle on my 15" Colchester is about 3" in diameter and it is not considered a particularly heavy lathe.

      Comment


      • Every now and then I come back looking around, hoping things have changed. Of course they haven't. If anything, they are worse.

        I don't post projects here any more. It's a pity grown ups can't act a little more grown up.

        Evan, looking forward to seeing your progress, whether it is documented here or on your personal site.

        Sincerely,

        BW
        ---------------------------------------------------

        http://www.cnccookbook.com/index.htm
        Try G-Wizard Machinist's Calculator for free:
        http://www.cnccookbook.com/CCGWizard.html

        Comment


        • Originally posted by JRouche
          Too bad there wasnt a thread lock function where a "build thread" could only be updated by the original poster to update the build progress. Would make it so much easier to view the build.
          The BBS software I run allows users to lock threads they start. I'd be surprised if VBulletin didn't. I think it is appropriate for a Projects forum, and for tutorial type content. Unfortunately, in the software I use (SMF) it is a global option so applies to all forums.

          Comment


          • Another thing that I would seriously look at it using a spindle that is that small on a big swing lathe. From past experience I think that you are going to have enough flex in the spindle to cause chatter when you try to turn larger parts. The spindle on my 15" Colchester is about 3" in diameter and it is not considered a particularly heavy lathe.
            I'm not building a big lathe. I am building a little lathe with a big swing. I considered jacking up my SB but decided that I would be better off with two work lathes. I need to turn large diameter work from time to time. For instance, my telescope design was constrained by the size of the SB9 lathe.



            The rings are exactly 9 inches outside diameter. If I had the capability when I built it I would have made it an 8 inch scope instead of a 6 inch scope. I don't have a need to turn large heavy parts, just large parts. Putting the centerline higher above the bed in no way makes the lathe somehow weaker or stronger for that matter. As long as it is properly designed it will work fine.


            I really don't understand all the fuss about this bearing. It is a preloaded bearing with ten times the capacity it needs to have. It is completely rigid with no axial or radial play. Because it is so wide and rigid it will provide a much greater degree of support to the spindle nose than would normally be the case. The spindle at that point is 2" OD. You could cut off the rest on the other side of the nose bearing and it would still work. The bearing is a heavy temperature assisted press fit on the shaft. That is a part of the preload.

            The bearing will work. There are plenty of usable lathes that have far less in the way of spindle bearings.

            All my working life nearly every single job I have had, and there have been many in the early years, every job has had something to do with machines. Either building or maintaining, repairing or operating them and even designing them.

            In fact, everything I build is my design. Even as a child I designed my own toys, games and models and built them. I have been designing machines since I was about 5 years old. It's what I like to do more than anything else. I like machines and the principles of operation that underlie everything we invent and exploit.
            Free software for calculating bolt circles and similar: Click Here

            Comment


            • Nice looking 'scope Evan, i can understand why you need to turn large but lightweight parts.

              I am saddened by the state of this thread, i can see maybe 1-2 pages of worthwhile stuff and 12 pages of deep in-depth analysis of a bearing! I dont recall you asking for someone to pull your project apart, if you feel that your design will work (and i am sure it will in this instance) then why the need for it to be redesigned by others?

              It would be ggod to be able to lock your own threads here, as it is a better site than PM due to its current interface difficulties and i view this s ite more often. !6 pages of comments on a project build - wow!

              It certainly puts me off wanting to post pics of projects.

              Dave
              If it does'nt fit, hit it.
              https://ddmetalproducts.co.uk
              http://www.davekearley.co.uk

              Comment


              • "Putting the centerline higher above the bed in no way makes the lathe somehow weaker or stronger for that matter."

                Not that it's quantitatively significant in your application, but increasing the centerline height lengthens the moment arm of the forces, increasing stress and deflection in all of the machine structure in the load path between work and cutter.

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                • all the best.markj

                  Comment


                  • OK one last post before we leave it to Evan seeing as I was probably the one who derailed the post, which wasn't my intention.

                    Some points first that have already been covered in the post. This 5310 bearing is a double row angular contact with no adjustable preload other than manufacture and assembly.

                    They are designed for loads where the thrust is from both sides, wheel bearings and as Lazlo has said the knee on a Bridgeport which is presented with loads from two directions, ie. wind up, wind down.

                    A lathe doesn't have these opposing forces resulting in one race doing next to nothing.

                    Will it work in Evan's case ? Sure it will and work well given the bearing size and the loading.
                    From one table published it has a loading of nearly 82,000 Newtons [ it's the sealed bearing with a lesser loading ] more than enough.

                    A single row angular contact bearing of the same ID / OD has a loading of 76,000 Newtons. So the bearing manufactures accept that one race is doing very little hence only 6,000 Newtons difference.

                    I whole heartedly accept that this will work for what Evan wants it to do, hell even one deep groove has a loading of 64,5000 Newtons and it's heavy duty mate is rated at a whopping 84,500 Newtons.
                    I also accept that Evan used this as it was available for free, and that rates high up on the list.

                    My mistake was to point out to people following the thread that it wasn't the best choice. Looking at the data above just one angular contact bearing with an ordinary ball race at the back, or even a second angular contact would give or exceed the specs of this bearing.

                    After that I was told by Evan why it would do what the manufactures say it will not do by design.

                    In typical Evan fashion he then twisted words, ignored questions and even posted the Nachi link which disproved his theory.

                    Spin Doctor who worked on high speed spindles all his life even came to my rescue and was ignored, so much for experience.

                    My post # 37 basically says the same as this post.

                    This all isn't aimed at Evan, it might look that way after it got out of hand. There isn't a right and wrong way to do many things in this trade there are just many ways and if people can't see that then they are either thick or blinded by their own importance.

                    I don't know everything that's why I come here, I learn a lot. I learn a lot from Evan as I know sod all about many subjects but I do know there are alternative ways to do most things.

                    So basically this is a tongue in cheek apology, not to Evan as I don't feel I have slighted him, his bearing WILL work, but to the rest of the readers on this forum for allowing the thread to run away.

                    .
                    .

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



                    Comment


                    • his bearing WILL work,
                      That's the part you failed to mention at the outset John. It would have gone a long way if you had.
                      Free software for calculating bolt circles and similar: Click Here

                      Comment


                      • Originally posted by Evan
                        That's the part you failed to mention at the outset John. It would have gone a long way if you had.
                        I did but it took me until post # 37

                        .
                        .

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



                        Comment


                        • [So basically this is a tongue in cheek apology, not to Evan as I don't feel I have slighted him, his bearing WILL work, but to the rest of the readers on this forum for allowing the thread to run away.

                          .[/QUOTE]
                          I don't think an apology to the "rest of the readers" is needed. I, for one, enjoy spirited discussions. Is that not the scientific method? State your position, back it with evidence and argue back and forth..supposedly that is how we all can come to the best conclusions.

                          There is a lot to be learned from this forum, egos often cloud the issues but that is often the case with people who are good at what they do.

                          Comment


                          • I've learned a lot from the thread that I never knew a thing about, so there have been some benefits for me at least. On the whole it's been a mostly technical discussion without descending too far into personal ego-bashing. Some points a bit too heavily-laboured and dragged-over but on the whole a discussion with many merits I think.
                            Peter - novice home machinist, modern motorcycle enthusiast.

                            Denford Viceroy 280 Synchro (11 x 24)
                            Herbert 0V adapted to R8 by 'Sir John'.
                            Monarch 10EE 1942

                            Comment


                            • I'll be posting further progress in a new thread for now. This one is too deep to wade through. We'll see how it goes.

                              John, the way you came across to me is that you were slamming my choice of bearing even though it wasn't a choice. You didn't allow the possibility that it would serve until it was too late. That wasn't the only issue though. It really gets me steamed when somebody implies that I am lying. The measurements I made are real and I took care in making them.

                              You may have noticed my setup. There is a small cast iron table that is keyed to the ways by underside vee grooves. A large lead weight holds it in place and provides damping. The mag base clamps directly to the table and the indicator is mounted as close as possible to the base to minimize deflection in the support. Without such measures it isn't possible to obtain reliable readings in that range.
                              Free software for calculating bolt circles and similar: Click Here

                              Comment


                              • Holy Smoke! What a wild runaway happened here...
                                Ummm..."this will kill the board"...lol!
                                How many times have I heard that..and it's still here.
                                I am sorry to hear from a couple of respected members here that they no longer post their projects on here.

                                I post a lot of my "Rube" inventions on here. I do it with an open mind.
                                Yup...I think my way is the best...or I'd buy what i needed from Crappy Tire.
                                I've been sorta disappointed a few times that my genius wasn't recognized
                                That my idea wasn't the BEST way...
                                So I just tell myself..."Sukk it up Princess and learn from those who actually know the subject".

                                We seem to be a large collection of open minded thinkers here.
                                We don't need the "See the plans".
                                We already saw the plans...in our heads.
                                Sometimes our plans need adjustment.
                                Sometimes....it turns out we are right no matter what the experts say...
                                Russ
                                I have tools I don't even know I own...

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