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Thread: Turning B&S 9 to R8 question

  1. #11
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    Quote 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.

  2. #12
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    Quote 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".
    Quote 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.

  3. #13
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    Quote 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 at 03:36 PM.
    .

  4. #14
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    Quote 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.

  5. #15
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    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.

  6. #16
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    BCRider, thanks, you brought up some good talking points.
    The nose on the little mill is about 1.750, and big end of BS9 is 1.07xx.
    I had asked about 30 taper because I noticed the big end is 1.250 same as R8. The taper looks the same, that is why I asked to compare.
    I question this please,
    R8 runs up to 3HP on the big Bridgeport, and R8 is actually a smaller taper than NMTB30. But, 30 has the drive dogs, and it is a more shank on the taper.
    So, if R8 is smaller than 30, why does R8 run without drive dogs??

  7. #17
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    Quote Originally Posted by BCRider View Post

    Yeah, grinding would be nice. But if you don't have the proper stuff that jacks up the cost a LOT.
    Nice or necessity? Do we think/know for some reason the spindle is not hardened? Without specific knowledge of the mill, aren't the odds that it is; spindle are suppose to be hardened and ground in which case its for sure its a grinding job. i'm a bit challenged to see how grinding on the lathe is going to be as good the a (presumably) well made factory spindle. Its a lot of grinding and heat and risk imo.
    .

  8. #18
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    A crazy thought, join the Yahoo groups Sheldon or Burke group. Ask if anyone has converted their milling machine spindle from B&S 9 taper to something more common. That should get yo0u time/effort/cost information.

  9. #19
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    I had it done.

    Wells Index did mine for my millrite mill.

    I paid around 300 bucks.

    Here is the head page from my mill clean up project
    http://www.mikeamick.com/millrite_project/head.htm
    Last edited by Mike Amick; 05-29-2019 at 01:20 AM.
    John Titor, when are you.

  10. #20
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    I called wells index already, that is over $600 now. for the same $600 I could probably tool up for BS9. this little mill might not be worth 600.

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