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Cutting a V-Grove Pulley

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  • #31
    With a small diameter pulley, you need to get hold of the type of vee belt with the internal segments. They are called cogged belts.

    https://www.globalspec.com/learnmore...v_belt_pulleys

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    • #32
      If you have access to a Machinery Handbook the pulley angle for various pulley diameters and minimum wrap angle is there.
      A long time ago I made these rough gauges to check pulley groove angles and they have come in handy at times.

      Click image for larger version  Name:	groove degree tools.jpg Views:	33 Size:	87.2 KB ID:	1949926
      Last edited by Ridgerunner; 07-04-2021, 10:52 AM. Reason: clarify

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      • #33
        This link which was kindly given to me on another forum may be of use when designing vee belt systems:

        https://ptandbs.com.au/reference-2/b...th-calculator/

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        • #34
          Googling overwhelmed me and my ADHD gets in the way. The suggestion of machinery handbook was a good one. I couldnt find info for metric so opted for the evil imperial system ,Im sure its close enough. If I understand the charts the angle is 30 degrees on a 4l belt smaller than 65mm in diameter . Ive machined it and is good. Thanks for the suggestion

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          • #35
            Originally posted by old mart View Post
            This link which was kindly given to me on another forum may be of use when designing vee belt systems:

            https://ptandbs.com.au/reference-2/b...th-calculator/
            Note that the calculator assumes that the belt wraps each pulley 180*, regardless of their relative sizes and distance apart.

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            • #36
              Originally posted by Ridgerunner View Post
              If you have access to a Machinery Handbook the pulley angle for various pulley diameters and minimum wrap angle is there.
              [snip]
              Thanks - I never knew that the angle depended upon the pulley size. I guess that means that the pulley angle may be different than the belt angle. How does that work?

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              • #37
                Originally posted by old mart View Post
                You need to check the angle of the threads, your lathe spindle may have 55 degree Whitworth form........Reverse with an unlocked threaded spindle is safer with low backgear speeds and gentle cuts. I have made this drawbar for the Atlas in case reverse is ever used, it does block the spindle bore and relies on the chuck bore being large. ..........
                No, Its a standard 1-1/2 x 8 Spindle 60 degree V thread.
                The Boxford is a Improved version of the Southbend Lathe and all attachments are interchangable with Boxford.
                My Boxford AUD has a Southbend Taper Attachment on it and SB Steady-rest It came with Pratt and Bernard Chucks (UK) , but my 6 " Buck Chuck ( USA) works fine. Even the cross-slides and tool-slides can interchange

                During WW II , The US loaned drawings for the Southbend Lathe to the UK as part of the war effort.
                When the war ended, the Brits came up with great revisions ( Timken headstock, Large Dials,Torrington Needle bearings, Dynamic one step Back Gear arrangement-hooray ! ) and created the Boxford but used the same Way spacing and general arrangements

                Rich
                Green Bay, WI

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                • #38
                  Originally posted by Bob Engelhardt View Post

                  Thanks - I never knew that the angle depended upon the pulley size. I guess that means that the pulley angle may be different than the belt angle. How does that work?
                  The way I understand it is when you bend the belt around a smaller pulley it expands on the inside belt edge making the angle less.

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                  • #39
                    Originally posted by Rich Carlstedt View Post
                    When the war ended, the Brits came up with great revisions ( Timken headstock, Large Dials,Torrington Needle bearings, Dynamic one step Back Gear arrangement-hooray ! ) and created the Boxford but used the same Way spacing and general arrangements
                    Rich
                    Rich -- I haven't heard of a one step back gear. Can you give a description?

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                    • #40
                      I don't know how Boxford designed a one step back gear, but Smart & Brown model A toolroom lathes had a major backgear redisign during their production. The early model (Mk 1.5) at the museum requires withdrawing a locking pin between the pulleys and the spindle first, and then engaging the back gears using an eccentric shaft. The later (Mk 2) used a single lever to do both things at once, which is much stronger and quicker.

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                      • #41
                        Yes, Boxford did introduce single lever operation for the backgear, with the usual proviso that the machine had to be stopped before changing gear. According to www.lathes.co.uk, only the early Boxfords up to serial number 1360 had the Southbend spindle nose. after that it was the same diameter and pitch but 55deg Whitworth thread form.
                        '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

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                        • #42
                          A related question when boring the center hole I over shot the size just a hair. It is still usable, but I think I am going to redo and try for a tighter fit. Is it better to ream the last little bit? If so do I look for a morse taper reamer that held in the tailstock or it is better to ream by hand?

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                          • #43
                            Originally posted by donf View Post
                            A related question when boring the center hole I over shot the size just a hair. It is still usable, but I think I am going to redo and try for a tighter fit. Is it better to ream the last little bit? If so do I look for a Morse taper reamer that held in the tailstock or it is better to ream by hand?
                            The pulley has a Morse taper? Are you sure - your drawing doesn't show a taper.

                            EDIT: Oh ... a MT shank! Brain cramp! Thanks for not ridiculing my confusion.
                            Last edited by Bob Engelhardt; 07-20-2021, 03:03 PM.

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                            • #44
                              Originally posted by Bob Engelhardt View Post

                              The pulley has a Morse taper? Are you sure - your drawing doesn't show a taper.
                              The pulley design is accurate, no its not tapered. I was asking about the reamer. If a reamer is the best way to make a consistent hole size if have two choices. Purchase a hand reamer and ream the hole by hand or purchase a reamer that's held in the tail stock. For a Boxford that's an mt2.

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                              • #45
                                Just a thought: why not build up the inside of the hole with JBWeld and rebore?

                                -js
                                There are no stupid questions. But there are lots of stupid answers. This is the internet.

                                Location: SF Bay Area

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