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  • Boring! Lunacy or genius?

    Hi all. I'm sure this is a very noob question...but that's where I'm at
    I've bought a tailstock die holder for the 25mm thread dies I have. The holder is fractionally under-sized. I knew this when I bought it but figured it shouldn't be too much hassle to skim around 0.3mm off the ID. The question is, what with?

    I've got some TCT boring bars for a mill but they're all 12mm cylinders with no flats. I could buy a square sleeve but will have to check it isn't too big for my QCTP.

    I've got a pre-shaped 10mm HSS boring tool but I've not had great results with the other tools and found the carbide soo much better. I'll admit to being both lazy and grinder-inept in my preference for inserts

    My preference would be to use the DCMT RH turning tool I have but is this a bad idea and if so why please?

    Also have to get the part running true so it could be a good excuse to get the 4-jaw mounted for the first time

    Many thanks,

    Gareth

  • #2
    Admit it! You are just looking for excuse to buy these:
    https://www.banggood.com/5pcs-810121...r_warehouse=CN

    And this:
    https://www.ebay.com/itm/S12M-SDUCR0...0AAOSwcLxYGER2
    Location: Helsinki, Finland, Europe

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    • #3
      It's not an excuse I need....it's unmarked packaging and delivery direct to the man-shed!

      Prices are good but most are two big. I reckon I could shoe-horn a 12mm in but 16 and 20 would take a lot more imagination! Already spent my "I'm not spending anymore money for the moment...oh, shiny!” money on an SER1010H16 (It's actually 10x12mm shank) threading insert holder that turned "threading doesn't work!" into "Oh, that was easy" The 16mm inserts come in a larger range than the 11mm and you can get full-profile inserts for maximum ineptness compensation

      Interested from a curiosity (academic if you like) viewpoint whether a DCMT right-hand turning tool would be good, bad or ugly for boring and why.

      Gareth

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      • #4
        It may not have enough relief to clear the bore below the cut.
        Boring tools have a lot of relief because the bore curves back under the cutter.
        When turning the work curves away from the cutter so much less relief is required.

        Mount it up and use the best tools in your shop. (Two eyes connected to a functioning brain)

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        • #5
          Yeah, relief is going to be problem in a 25mm hole.

          Mount it way above centerline and rotate the toolpost to gain little bit of extra clearance can work in a pinch.
          Location: Helsinki, Finland, Europe

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          • #6
            You have a mill and boring tools. I assume you have a boring head. Set the job up in the mill.

            Another way is to make a holder for the boring bar that fits your toolpost.

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            • #7
              Ah, I see. I was only thinking about clearance in the horizontal plane but the issue is with the bottom of the insert holder hitting the ID. It might work with a tilt but it'd be so close it's not worth the mental anguish!

              Good call on setting it up in the mill. The lathe is the new toy (can ya tell?!) so it hadn't even occurred to me not to do it on that - especially when the job has lathe written all over it! Time to get the mill leveled in its new home on the workbench of unlevelness then. Coaxial indicator is on my Christmas list....would be damn useful right about now!

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              • #8
                An edge finder is another easy way to find center on a round feature in a milling setup.
                Kansas City area

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                • #9
                  Originally posted by Toolguy View Post
                  An edge finder is another easy way to find center on a round feature in a milling setup.
                  I was going to sweep with a DTI and hope for the best but I'll give that a go too and compare the results. Seems it may be easier with a DRO - got any tips for compensating for backlash? Find one edge, take out the slack and then measure from there?

                  OT: Got the mill leveled but have to clear a job that's set up first - everything was thrown into chaos when the lathe arrived. Have a 3MT fly-cutter that I modified (wider slot) to take a 10mm LH CCMT lathe tool. Did this because the HSS bit blunted too quickly and then work-hardened the HRS surface. The result was fairly flat but far from pretty. Got a cheap (£10 inc shipping) CBN CCGT. Result is great. 640rpm, 1.5mm/4 seconds feed and about 0.2mm DoC. Rainbow-patterned but reflective. Nice!

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                  • #10
                    If you have boring bars then you need a boring bar holder. If your new lathe came with a boring bar holder then use that and make up a split shim as required. Or if you don't have such a tool holder then get a hunk of heavy stock and drill it for a hold down bolt then line it up and self drill it in your lathe. The two sizes shown on the holder on the left were done this way. It's my standard boring bar holder. For the hold down and the relief flexing hole on the smaller size the holes were done in the drill press.

                    Chilliwack BC, Canada

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                    • #11
                      The OP is increasing the ID of a die holder that has either a 3MT or 2MT tapered shank. This is not going to be easy to setup in the mill.

                      WAY better to hold it in the lathe by the flats of the OD of the die holder. In a 4-jaw the ID can then be used to get to minimal runout.

                      The depth of the bore is only around 10mm and he only needs to take off a wee little bit from the ID.

                      There are a lot of options for the "tool" to do the boring with in the LATHE. Perhaps even put a 2-flute milling cutter in between a couple of aluminium strips (grove them if you must); so that the tip of one of the flutes is pointing to where you need it.

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                      • #12
                        Learn to grind your own, it wil, get you thru anything.
                        Here is what I would do..
                        Mount a block of aluminum in a QCTP holder , about 1. 5 x 1 .75 sticking out and 3 inches long.
                        Set it up so that this piece is parallel to the ways the position it so you can drill/bore/ream a 1 inch hole in the block, with at lest 1/4 INCH OR MORE meat left on side away from the QCTP.
                        Bore and finish 1 inch hole then drill, tap, and slit the outside part so it can clamp a 1 inch bar.
                        Then get a 1 inch straight sleeve from KBC with a Morse 2 taper inside it.
                        Now you can hold the dies with you QCTP , way easier than using tail stock on long stuff.
                        Now here is the best part,
                        Now you have power feed for drilling.

                        Comment


                        • #13
                          Originally posted by Norman Bain View Post
                          The OP is increasing the ID of a die holder that has either a 3MT or 2MT tapered shank. This is not going to be easy to setup in the mill.

                          WAY better to hold it in the lathe by the flats of the OD of the die holder. In a 4-jaw the ID can then be used to get to minimal runout.

                          The depth of the bore is only around 10mm and he only needs to take off a wee little bit from the ID.

                          There are a lot of options for the "tool" to do the boring with in the LATHE. Perhaps even put a 2-flute milling cutter in between a couple of aluminium strips (grove them if you must); so that the tip of one of the flutes is pointing to where you need it.
                          Good point. And given that most lathes have a morse taper of some sort in the head stock spindle a good time to either buy a suitable MT adapter or to buy at least a MT to parallel holder that allows such tooling with MT shanks to be held in a four jaw chuck.

                          This certainly falls under the "tool to make a tool" banner. But it's an issue that is very likely to arise in the future at fairly regular times.

                          Usually the lathe comes with an MT2 or MT3 solid center and an adapter to allow using that smaller size in the more normal MT4 or MT5 taper found in a lathe spindle. So he may not even need to buy anything.
                          Chilliwack BC, Canada

                          Comment


                          • #14
                            Originally posted by BCRider View Post
                            If you have boring bars then you need a boring bar holder. If your new lathe came with a boring bar holder then use that and make up a split shim as required. Or if you don't have such a tool holder then get a hunk of heavy stock and drill it for a hold down bolt then line it up and self drill it in your lathe. The two sizes shown on the holder on the left were done this way. It's my standard boring bar holder. For the hold down and the relief flexing hole on the smaller size the holes were done in the drill press.
                            I didn't get a boring bar holder with the lathe unfortunately. Do have a QCTP which I've just managed to make a passable post with which to mount it. Are your tool holders designed to mount in place of the tool post block?

                            The die stock holder unfortunately doesn't have a Morse taper - it'd make it easier to centre. I wanted one that did but I didn't need 6 different sizes of head (all my dies are 25mm) and I wasn't prepared to pay £50 for the set that had a 2MT. This one was £18 and single size only. The body slides on a parallel shank to be held in a drill chuck. It's a compromise but it should be adequate. The shank comes out so it should be possible to hold it on the mill...in a lathe chuck ironically.

                            Grinding my own: I'm aware it's the sensible option. It's not something I'm very good at and I don't get a lot of time to learn the art. My grinder also had to make way for the lathe - my entire work area is 2.3 x 1.4m - so it's now on the bottom shelf of the bench. Usable (just) but far from ideal.

                            Headstock is 3MT and tail is 2MT. I do have dead centres in both. Trying to resist the urge to fix the problem by throwing money at it....have already run out! I do have a bar of scrap Aly that seems to be a reasonable grade. Is that likely to be strong enough to make boring bar holders for the TCT bars I have already or would it be a case of getting away with it for such a light skim but useless for anything more serious?

                            Thanks for all the replies everyone. It's good to get my head around lots of different ways of cracking the problem and definitely better to learn what's a bad idea from more experienced machinists (right now I'll admit that's everyone!) rather than by picking shards of hot metal out my face!
                            Last edited by Cenedd; 11-12-2017, 05:56 AM.

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                            • #15
                              Most lathes come with no toolholders.
                              Grinding your own, will always save you money it's the cheapest way out.
                              None of us were good at this, until, until... we applied ourselves, and made a conscious decision to learn how to do it.

                              You should post your location. Help may be nearby m or someone may know of a place near you to get small pieces of material for cheap .
                              Last edited by 754; 11-12-2017, 01:15 PM.

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