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Logan lathe tailstock MT#2 tool holder question

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  • Logan lathe tailstock MT#2 tool holder question

    Hi,
    I would appreciate some advice on how to hold a milling cutter on the tailstock on my lathe.
    194x Logan 850-2.
    Normally I would just chuck a drill-bit in the Jacobs or Albrecht chuck, mounted in the MT#2 tailstock.
    But this project is 6AL4V Titanium.
    I realize it may be stupid to try to cut this in the ancient Logan.
    However, I was able to cut threads, using Warner tooling, and catalyzed Sulphur lubricant, (Habcool-318) no problem.

    Click image for larger version

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    I need to hold a solid carbide 19/32 cutter, so as to make a hole in the Ti, where the live center is in the photo.
    As you may know, Ti work hardens in an instant, so I only get one chance to make this hole.
    After the 19/32 hole is in the part, I have an OSG 5/8-24 tap for it.
    The tap is made specifically for Ti.
    Thus I am not going to try it w/ a 19/32 drill bit.
    Found a collet kit w/ MT#2 holder on ebay, would that be a good thing to try for this, or is there a better option?

  • #2
    what's the worry about holding the endmill in a drill chuck? It should only experience a thrust load, just like a drill. Personally I'd drill a small pilot the size of the web of your finish drill and then just drill it. Slow speed, hard feed, plenty of oil, no dwelling anywhere and you should be fine. I've not done a whole bunch of drilling with center cutting endmills, but I generally find the feed pressure to be higher than with a drill, which isn't what you want in a work hardening material.

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    • #3
      The nose of an end mill is not going to want to start out clean and at the right size unless you can do a conical start to aid with centering the cutter lips. I'm not sure that your tail stock will be rigid and fitted well enough to avoid an oversize hole for at least the first part of the hole. It may or may not steady up as it cuts deeper. Frankly if you need solid carbide to avoid the tool dulling and thus work hardening the Ti then perhaps a solid carbide DRILL bit would be a better option? It may also require a 4 facet cut all but the smallest part right at the center point can be a cutting format.

      As for which holder for the carbide end mill? Due to the hardness of the carbide shank an ER collet chuck with MT2 shank would be held with better grip than a regular drill chuck. And it would perhaps allow you to cut at a good enough chip load to avoid rubbing and work hardening the Ti.

      Chilliwack BC, Canada

      Comment


      • #4
        Could try a morse taper collet sized to the end mill - but then you need a drawbar and such. Could use an MT2 arbor blank and make an end mill holder from it. Or, yeah, just use a drill chuck.

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        • #5
          I found some solid carbide 19/32 drill bits on ebay, would like to try one instead of the end mill idea.
          Some say “screw machine” does that require some special mount, or can I just put a “Screw machine” drill in a normal chuck?

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          • #6
            Normally a screw machine drill is about 1/2 the length of a normal drill bit. Depends on how deep you need to go. I would just drill it with a good 1/2" drill bit, then a 19/32 drill bit. That particular alloy of Titanium is not hard to machine if you keep the spindle speed down to around 200 to 250 rpm. Use sharp cutting tools and cutting oil, should walk right through it, even with HSS tooling.
            You may want to get an ER32 chuck with MT2 shank and a set of collets for future projects where you need an endmill in the lathe.
            Kansas City area

            Comment


            • #7
              Thanks!
              Seems like a short drrill bit would be ideal to reduce any flexing. I only need .625 depth.

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              • #8
                Screw machine drills are short, good for smaller size machines anyway.
                and usually split point, which work hardens less.
                i d not know why you cant drill 1/2 or 9/16 , then bore to size..

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                • #9
                  Use an end mill holder. With no draw-bar, the collet will probably not hold well.

                  A drill will be better, most likely
                  2730

                  Keep eye on ball.
                  Hashim Khan

                  Everything not impossible is compulsory

                  Comment


                  • #10
                    If it's a center cutting end mill then there would be enough pressure needed to clear the center that the morse taper would be fine as far as not needing the draw bar. But one would need to be careful if using an end mill drilling into a pilot hole.

                    I suspect the bigger issues that makes using the drill bits a better idea is that the drill bit will more easily start a well centered hole. An end mill will try to walk around and cut an oversize and non round hole as it starts.

                    I'm also thinking the same question as 754. Seems like for a few holes which are only .625" deep that drilling 1/2" and boring would be a lovely way to go what with giving a truer hole shape and certainly a truer size.
                    Chilliwack BC, Canada

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                    • #11
                      However work hardened your titanium gets it will be no match for a solid carbide drill. You will need a drill intended for hard steel, not for other materials. You should get good size and finish also.

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                      • #12
                        Originally posted by Toolguy View Post
                        ...You may want to get an ER32 chuck with MT2 shank and a set of collets for future projects where you need an endmill in the lathe.
                        This is what I was thinking. ER collets are great. You can get sets for reasonable money too.

                        -D
                        DZER

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                        • #13
                          Originally posted by Doozer View Post

                          This is what I was thinking. ER collets are great. You can get sets for reasonable money too.

                          -D
                          I actually made an ER32 collet chuck for my spindle, threads directly on.
                          Thru hole same diameter as thru the spindle.
                          Best thing since sliced bread.
                          Save a ton of time and aggravation because you don't have to indicate everything.
                          25 miles north of Buffalo NY, USA

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                          • #14
                            Jam up, Van Man ! ! !

                            -D
                            DZER

                            Comment


                            • #15
                              I have an ER32 and ER40, both with MT3 taper shanks for the tailstock. I use them fairly often, sometimes with an endmill, but mostly for larger size drills that won't fit in the drill chuck.
                              Kansas City area

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