Announcement

Collapse
No announcement yet.

Southbend backplate register

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

  • Originally posted by SLK001 View Post

    If there is a 1/2" space between the chuck and the spindle shoulder, then you don't have a register at all. You are simply butting up against the end of the threads. If the backplate was fit to the chuck like this, then it will seem that it is "registered". What you have is a soft cast iron backplate running to the end of a hardened spindle. Over time, the cast iron backplate will peen down where it meets the end of the thread and throw out your alignment. It will be barely detectable at first, but will continue to progressively get worst over time. You should probably make a decision now to fix your setup, before it becomes unusable in the future. Decide which area you want to register on - the spindle shoulder or the area with no threads. Either one will be better than what you have now.
    I was mentally eyeballing the wrong part of the back plate. But did learn that the (small, no-name) 3 jaw chuck that came with my 2nd 820 wasn't contacting the shoulder. Compared it with the Buck, and the undercut differed by almost a tenth and a half! .143. I have no idea what lathe the backplate may have been fitted for, but it wasn't a Logan 10". Haven't decided if I want to make a backplate, too many "I'm a gunna" as it is, or sell the thing with the disclaimer I have no idea what lathe spindle the undercut is sized for.

    Appreciate your time.

    Ron

    Comment


    • Chuck that little chuck (you said it) in a bigger one and open out the undercut to fit so it screws down against the shoulder. No need for a precise fit on the spindle for that, 20 thou loose is fine. So is 30......

      BTW...... a "tenth" usually means 0.0001" i.e. a tenth of a thou. 0.100 is 0.100, even though it is a tenth (of an inch).
      Last edited by J Tiers; 08-25-2021, 07:01 PM.
      2730

      Keep eye on ball.
      Hashim Khan

      Everything not impossible is compulsory

      Comment


      • Originally posted by J Tiers View Post
        .-------- No need for a precise fit on the spindle for that, 20 thou loose is fine. So is 30......

        .
        Sigh. I'm saying nothing---.

        'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

        Comment


        • Originally posted by Richard P Wilson View Post

          Sigh. I'm saying nothing---.
          Because he is correct?
          21" Royersford Excelsior CamelBack Drillpress Restoration
          1943 Sidney 16x54 Lathe Restoration

          Comment


          • Originally posted by J Tiers View Post
            Chuck that little chuck (you said it)
            LOL, still a 8", but point taken.

            Originally posted by J Tiers View Post
            BTW...... a "tenth" usually means 0.0001" i.e. a tenth of a thou. 0.100 is 0.100, even though it is a tenth (of an inch).
            Again, point taken. Gotta do a better job using the common terms.
            Last edited by Shiseiji; 08-26-2021, 09:08 PM.

            Comment


            • Originally posted by The Metal Butcher View Post

              Because he is correct?
              No, because he isn't, but I'm fed up trying to persuade you lot.
              'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

              Comment


              • I finally remembered to measure the spindle of the 12 x 24 Atlas, and it is not exactly the same as the SB dimensions in post #76. Overall length is 0.698" (SB 0.6875"), register diameter 1.498" (SB 1.509"). This spindle shows little evidence of wear. The backplate that I made to fit it would not fit on a South Bend as the bore of the register was made 1.499".

                Comment


                • So I made the second backplate for my mates three jaw. He roughed it out and I did the finishing. This time round it was much quicker. First time was 30 hours of googling and one and a half days of machining. This involved making a dummy spindle and internal threading tool.
                  Second time round maybe took me two and a half hours.

                  My first register I did was 38,6 so I tried getting it better this time round. A mistake . I measured the register wrong but its not so easy to measure .Its a dark garage and using a borrowed dial vernier that I dont know how to read doesnt help. A micrometer doesnt go on because the jaws bump on the Spindle face. I measured it wrong and made my register 38,1mm
                  This meant I had to clock it up and recut it. I managed to set the backplate by eye to 0,2mm just by eyeballing it and clocked it in within 0,01 to the spindle axis and 0,04mm on the facing axis which is good enough for me . It fit on perfectly . All in all it took me about two and a half hours . Funny how when you get used to something it becomes so much easier. I normally machine through necessity ,not really for hobby stuff but I must say its alot of fun getting stuff done.

                  Comment


                  • Good result, Plunger, it would be normal to give the front face a skim to exactly match the backplate to the spindle after screwing it on and off a few times to settle it down.

                    Comment


                    • Originally posted by old mart View Post
                      Good result, Plunger, it would be normal to give the front face a skim to exactly match the backplate to the spindle after screwing it on and off a few times to settle it down.
                      Yes my mate will do that on his southbend.

                      Comment


                      • Originally posted by plunger View Post

                        Yes my mate will do that on his southbend.
                        Sounds like you guys have it the way it should be
                        25 miles north of Buffalo NY, USA

                        Comment

                        Working...
                        X