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  • Spindle taper surprise....

    The vertical head I have for the small mill I have been using with 2MT attachments for years. Mostly collets, but also some other things. Some of the 2MT stuff came with it.

    The previous owner, who ran a small screw machine shop in N Illinois, had been doing the same, using 2MT in the head.

    So last night I needed to drill some holes and needed the precision of the table movements to position them. I don't have a drawbar 2MT adapter and chuck, so I used a small Cushman chuck on a tanged 2MT adapter.

    After I got done, I noticed that while it had worked, the taper was actually not the same as the adapter. There was a slight rattle, with the tail end loose. Checking with other 2MT tooling showed the same.

    Apparently the thing has a B&S #7 taper, which is similar to a 2MT, and the drawbar has been "covering up" the difference all this time. the two are quite similar, but have 25 thou or so difference at the small end with the 2MT seated.

    Since B&S 7 stuff is not too common, I probably need to change the taper, which may not be too easy. At least I do if I want to run non-drawbar attachments in it.

    You just never know.....
    1601

    Keep eye on ball.
    Hashim Khan

  • #2
    Originally posted by J Tiers View Post
    The vertical head I have for the small mill I have been using with 2MT attachments for years.
    Mostly collets, but also some other things. Some of the 2MT stuff came with it.

    ........ I probably need to change the taper, which may not be too easy.
    ...
    It's not that difficult, providing the head can be tilted, and you have knee-travel
    that exceeds the lenght of the taper in the receiver. Getting the Morse angle accurate
    is crittical. After that it just takes some care.

    Comment


    • #3
      B&S #7 is not that uncommon, especially in older machines. Little Machine Shop carries collets at a reasonable price;

      http://www.littlemachineshop.com/pro...4312&category=

      Solid tooling, such as taper shanks for drill chucks are a bit more difficult to locate, but the taper angle is much easier to duplicate than MT if shop fabricating. The two tapers are so close in size that machining to MT2 is a bit cringe inducing. If what you have works, I would be inclined to leave well enough alone.
      Jim H.

      Comment


      • #4
        I recall that ToolForCheep has the same chinee collets, same quality for less.

        Comment


        • #5
          Hmmm? Makes me wanna check my small milling head (bridgeport M) I have on my hardinge horizontal mill. It also is an apparent MT2 taper. I just assumed that cause it came with a bunch of MT2 tooling. But the M head also came with the B&S 7 taper. Gonna check. JR
          My old yahoo group. Bridgeport Mill Group

          https://groups.yahoo.com/neo/groups/...port_mill/info

          Comment


          • #6
            Just send it out for regrind.
            Amount of experience is in direct proportion to the value of broken equipment.

            Comment


            • #7
              JT,

              It might sound a bit crude, but couldn't you just clamp a straight-shanked 2MT taper reamer to a vee block on the table, run the mill at low speed and gently feed the spindle down onto it? From the sounds of it, you're only enlarging the large end by 25 thou or so.

              Centring it shouldn't be too difficult (run a dial gauge around the shank first). But even if it's a fraction off centre, as long as the reamer and spindle are both vertical, the taper will be correct.

              Ian
              All of the gear, no idea...

              Comment


              • #8
                Wells Index can regrind the spindle for you.

                Comment


                • #9
                  http://stores.ebay.com/superiormachi...=p4634.c0.m322
                  http://www.tools4cheap.net/products.php?cat=17

                  Boring heads? Drill chucks? Use a straight shank in a collet. What else do you really need?
                  Last edited by Arthur.Marks; 04-04-2014, 12:48 PM.

                  Comment


                  • #10
                    I had that surprise happen tool with a B&S 7 head when I put a tapered shank drill in there. But I did buy the Tool4Cheap collets. I also found an old stock endmill holder set and an old DA collet holder with collets on eBay that looked unused for good prices. So I'm tooled up. JimB
                    JimB

                    Comment


                    • #11
                      One good reason to change over is to be able to use all the tooling I already own, and avoid special tooling just for that machine. I will shortly have another small mill in operation that takes 2MT, so that would mean duplication out the wazoo.

                      It has already been really good to share tapers between lathe, horizontal mill spindle, and drill press. The lathe uses 2MT tailstock taper, so there is another batch of tooling already present...plus leftovers from the old 2MT drill press.

                      I still have to figure out if the spindle will take an MT 2 without trouble.... the #7 is slightly larger on the big end already, without much room to sink the taper in further, so there may be a problem.

                      I might have to make a new spindle entirely, or spend a bundle on BS7 .
                      1601

                      Keep eye on ball.
                      Hashim Khan

                      Comment


                      • #12
                        Originally posted by J Tiers View Post
                        One good reason to change over is to be able to use all the tooling I already own............

                        I might have to make a new spindle entirely, or spend a bundle on BS7 .
                        The name escapes me at presant, but there is 'Prehard' shafting made specificly
                        for making pump-shafts from, for pumps too old to get parts for in power-plants and etc.

                        It is machinable with insertable tooling, and even a good 8% cobalt H.S. bit will cut it
                        as long as you keep speeds reasonable.

                        If you're good on a lathe (a good lathe) Spindles just aren't that hard to make.
                        And it's a myth that it has to be ground to finish to be accurate enough.

                        Even a draw-bar hole won't require a special drill, just a good one and go slow.

                        . . . suddenly "StressProof" comes out of the cob-webs?
                        been over 35 years hmnnn.

                        Yup. that's it.
                        http://www.niagaralasalle.com/pdf/stressproof.pdf
                        Last edited by Old Hat; 04-04-2014, 11:00 PM.

                        Comment


                        • #13
                          That. or 4140PH.

                          I've made a bunch of MT3 tooling with 4140, some H-mill arbors, some shell end mill arbors, one drill chuck arbor, some other stuff. I'll be making a spindle for the other mill.

                          This one has a really well-fitting plain bearing spindle, ground and just plain nice..... It would be a lot of work to duplicate in a different taper. I might have to make some of the other tooling again in BS7.... The collets have been working, for me and the P.O. (go figure), so maybe I'd spring for them and maybe not. I really only need 1/2", 3/8" and maybe 3/16".. for cutters. Don't need a whole set.

                          You can get 1144, which is similar to stressproof, from McMaster. It machines well, and may be the exact same... the analysis is same, and finish is same, but I don't know if the same process is used. McMaster does not release much information, although you often can get the source info from the labels on their bags.... not for steel, though, I have some smaller sizes of McMaster 1144 in stock now.... no label.

                          The compound on the Logan will cover a 2MT or presumably a 7BS as far as length is concerned...(almost does a full 3MT, I just leave a longer tail) That's the easiest way to get a taper.
                          1601

                          Keep eye on ball.
                          Hashim Khan

                          Comment


                          • #14
                            StressProof isn't even that hard. It's game is that it's fairly strong without hardening, not that it's prehardened. They cold draw it in high draft dies so it's basically "forged rod stock."

                            You can cut it just fine with anything, it's machinability rating is 83%. Just remember, StressProof is strongest at the outer skin, if you significantly reduce the diameter you'll be left with a lot more "normal" steel.

                            If you really want "hard" without heat treating, 4140 Prehard sounds a lot like what Old Hat was mentioning, even more than StressProof.

                            Edit: J Tiers types faster.

                            Comment


                            • #15
                              Good points! Better than 4140 as long as you stay pretty close to the skin.
                              And will hold better against side-loading.

                              But; a Plain bearing arrangement all seated in and happy.
                              Leave the sleeping Dog lie, and get a few nice holders for it.

                              Comment

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