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Turning B&S 9 to R8 question

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  • Turning B&S 9 to R8 question

    I have a Sheldon horiz mill coming, it is B&S 9 spindle.
    I have found several options for getting tooled up.
    One option is to turn/grind B&S 9 spindle up to R8.
    I been looking at the taper shank dimensions on this site:
    http://www.tools-n-gizmos.com/specs/Tapers.html

    I cannot wrap my mind around the dims to bore up to R8, because guys on the other internet groups claim that after the R8 conversion you can go back an forth between either BS9/R8.
    If anyone is good with a CAD drawing, can you overlay the dims that I can see, an post that? or pm me?
    Personaly, when I look at the comparable dims on the listing I posted, I must question this:
    why not bore it up to NMTB30????

  • #2
    I don't know if it is dimensionally possible but there are a couple of questions that need to be asked because you didn't say.

    1. Are you going to do this yourself or farm it out.

    2. If you plan on doing it yourself do you have the skill and equipment.

    If you make a mess of this you don't have a mill at all just a boat anchor. If you do have the equipment and skills then what the hell why not, B&S collets are not common and expensive.
    Last edited by loose nut; 05-28-2019, 10:08 AM.
    The shortest distance between two points is a circle of infinite diameter.

    Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

    Southwestern Ontario. Canada

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    • #3
      You need to grind your spindle on an ID grinder
      like a Heald or a Bryant.
      Can also be done on a cylindrical grinder with a
      swing down ID attachment.
      Likely use a CBN mounted wheel.
      Set the angle with a standard or sine bar attachment.

      -Doozer

      -Doozer
      DZER

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      • #4
        loose nut,
        I plan to do this myself
        I think I got the skill and equipment
        I think I'm going to do one of 2 things:
        make my own B&S adapters to MT2, or just plain B&S9
        or,
        make a entirely new spindle of a common taper.
        saving the original BS9 spindle as a screw-up backup.
        Thats why I'm asking lots of questions before I dive in and screw up.

        The drive belts must be replaced, therefore the spindle is coming out regardless.
        Since the spindle will already be out, maybe I can duplicate it in R8, or MT3, MT2, or NMTB30, or.............?

        Comment


        • #5
          Doing the drawing sounded like a fun thing to do over morning coffee. The dimensions shown are what I'd use for making the sockets in the arbor and not the actual tapers. So the purple overlay of the B&S is a bit longer in the tail to allow for some positional variation and the open end is a touch smaller so the nose of the taper will stick out about 1/8 to 1/4". Same with the R8 done in black with green dimensions. It's longer at the parallel end and the middle is relieved out to 1" to allow easy inserting and the nose taper is shorter at both ends to reflect the wider midsection and so the tapered end will stick out about .05 to .06.

          I also see now that the B&S should likely switch to parallel about a 1/2" to 3/4" before the small end.

          Either way though this looks like it could be done if you choose to hog into the existing arbor. But I would say that your idea of keeping the original and making a new R8 would be the more prudent choice.



          But once again we get back to the idea that if your lathe has a compound that can travel for about 4" then you could pretty easily set up for making and fine tuning the fit for B&S tapers. The trick would be to find a B&S #9 socket to use for a "master" for rubbing the markings off the taper being made to see where a touch of metal removal is needed to get a good fit. Something like THIS ONE
          Chilliwack BC, Canada

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          • #6
            Wells-Index will regrind their spindles from B&S 9 to R8. They do it with the spindle mounted in the bearings. So, it is dimensionally possible. You might try giving them a call.

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            • #7
              Originally posted by gzig5 View Post
              Wells-Index will regrind their spindles from B&S 9 to R8. They do it with the spindle mounted in the bearings. So, it is dimensionally possible. You might try giving them a call.
              yeah, for 690$$

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              • #8
                BCRider,
                thanks, that is what I was looking for, just to wrap my mind around it.
                BTW, the R8 is undercut in the midsection is it not?
                Some drawings I saw were .949, some were undercut in midsection.
                Never saw any at 1".

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                • #9
                  The R8 spindle hole is straight. The collet.is.undercut for most of the length, with a full diameter section at the drawback 3d nd.

                  Sent from my SAMSUNG-SM-G891A using Tapatalk

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                  • #10
                    Originally posted by BCRider View Post

                    But once again we get back to the idea that if your lathe has a compound that can travel for about 4" then you could pretty easily set up for making and fine tuning the fit for B&S tapers. The trick would be to find a B&S #9 socket to use for a "master" for rubbing the markings off the taper being made to see where a touch of metal removal is needed to get a good fit. Something like THIS ONE
                    I would think that the spindle on the machine would be the best B&S #9 socket to use for a "master" for making collets and toolholders to match.
                    Kansas City area

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                    • #11
                      Originally posted by Toolguy View Post
                      I would think that the spindle on the machine would be the best B&S #9 socket to use for a "master" for making collets and toolholders to match.
                      Very, very true. And if the OP arranges to turn the arbors between centers driven by a dog then removing and replacing the arbor consistently would be doable. Not so much though if he opts to hold it just in the chuck where it won't return to center accurately without a lot of checking.

                      It could be done between centers for sure in all the situations I can see. And then after it's all done hold the well sized tapered arbor in the regular chuck to do the drilling and tapping for the draw bar last.

                      So yeah, good point.
                      Chilliwack BC, Canada

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                      • #12
                        Originally posted by Ringo View Post
                        BCRider,
                        thanks, that is what I was looking for, just to wrap my mind around it.
                        BTW, the R8 is undercut in the midsection is it not?
                        Some drawings I saw were .949, some were undercut in midsection.
                        Never saw any at 1".
                        Originally posted by shampine1 View Post
                        The R8 spindle hole is straight. The collet.is.undercut for most of the length, with a full diameter section at the drawback 3d nd.

                        Sent from my SAMSUNG-SM-G891A using Tapatalk
                        My own mill lets me insert the straight portion up fairly far until it engages the size for size portion. Which is why I showed that middle segment at 1" to mimic that relief. The smaller size for size portion shown would fully engage with the matching area of an R8 collet when inserted.

                        Also some collets might stick in the end if the hole is dead nutz on the 0.9495" size. The drawing I pulled off the web showed .9495 -0/+.0003. Likely wiser and easier if you aim for something between .9497 and .9500. But do try all your collets and size accordingly. For those that are a touch fat and sticky I'd dress them down a touch. Fit the spindle to the small and medium size collets since those will be in the majority.

                        The undercut in the middle of the collets is more to allow the segments to spring on the thinner walls than it is for clearance of the collet in the spindle.
                        Chilliwack BC, Canada

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                        • #13
                          Originally posted by Ringo View Post
                          or,
                          make a entirely new spindle of a common taper.
                          saving the original BS9 spindle as a screw-up backup.
                          Thats why I'm asking lots of questions before I dive in and screw up.

                          thats a lower risk suggestion. Mostly I'm with Doozer, modifying the shaft of the existing spindle this is a grinding job and not for the lathe. Factor in the cost of bearings though if you're making a new shaft.....and take lots pics and post them here

                          I guess the main reason for wanting to do anything is tooling availability? R8's are nice and common but not exactly the ideal taper. Is there room to make a Cat 30 spindle? Only you know your skill and equipment level but I'd be more inclined to leave the spindle alone if its in good working condition and make B&S 9 tooling
                          Last edited by Mcgyver; 05-28-2019, 03:36 PM.
                          .

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                          • #14
                            Originally posted by Mcgyver View Post
                            thats a lower risk suggestion. Mostly I'm with Doozer, modifying the shaft of the existing spindle this is a grinding job and not for the lathe. Factor in the cost of bearings though if you're making a new shaft.....and take lots pics and post them here

                            I guess the main reason for wanting to do anything is tooling availability? R8's are nice and common but not exactly the ideal taper. Is there room to make a Cat 30 spindle? Only you know your skill and equipment level but I'd be more inclined to leave the spindle alone if its in good working condition and make B&S 9 tooling
                            yeah, somebody please post a simple CAD drawing , overlay, of NMTB30 over R8.
                            Both of them are 1.250 on big end, and I think the tapers are the same.
                            Somebody please call this up in a computer to verify the same tapers.
                            30taper is 7/24 whereas, R8 is 16 degrees xxxminutes.
                            I think 7/24 is just a different expression of degrees/minutes.

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                            • #15
                              Look up how much tooling that you'll use is available for the 30 size and cost before you leap. Might prove costly.

                              One thing missing out of all this is the size of the nose on the arbor. The B&S is only around 1.07 on the nose of the existing spindle I'd bet. And given the angle of the NMTB30 I'm thinking that you'll want/need the drive dogs because there won't be much of a locking force with that angle of taper. So I'd say that calls for a new spindle for sure as you'll need a big enough nose to hold the drive dogs. So likely a bit more diameter to fit the 2.1 inch nose diameter and a touch more length to give good support to the dogs. So that sounds like it more than likely means a new main shaft.

                              What sort of lathe do you have? I'm thinking that if you can turn out the taper for the NMTB30 to start with then put a good holder in that end that will run on a center that you could then turn the outside between centers to obtain a good degree of concentricity. Then as a last step bore it for the drawbar which can tolerate a bit of wander.

                              Yeah, grinding would be nice. But if you don't have the proper stuff that jacks up the cost a LOT. And with a bit of care and some trickery you can obtain a nice fitting taper that has a smooth finish to start with and then move on from there on the outer work.
                              Chilliwack BC, Canada

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