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How to unshrink a hole

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  • #1

    How to unshrink a hole

    I have two Tormach tapping heads with TTS adapters. I wanted to be able to use it in a drill press with a #2 morse taper spindle so I bought a #2 Morse x 3/4" end mill adapter. It fit nicely except the set screw only catches the end of the Tormach holder so I needed to shorten it. In cutting it with a carborundum wheel it got very hot and I tripped the circuit on the table saw. So I finished using a 4-1/2" metal cutting diamond wheel on the hand grinder. In the process the hole apparently shrunk, the adapter no longer fits! How to open it up?

    I am thinking lapping it using a wooden dowel as a lap and some lapping compound while it spins in the drill press. Without buying more tools is there a better way?
    Tags: None
  • #2
    I'd start with just a chamfer. It's likely that only the very end is distorted.

    Dan
    At the end of the project, there is a profound difference between spare parts and left over parts.

    Location: SF East Bay.
    • 1 like

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    • #3
      Yup- probably just a burr on the end of the opening.
      Kansas City area

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      • #4
        Definitely not a burr or rolled over edge, already used the triagular scraper on it and created a substantial chamfer. Might have gone out of round.

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        • #5
          Lapping is the next thing I would do.
          Kansas City area

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          • #6
            Wait, table saw? As in, an abrasive cutoff wheel in a standard table saw is what you used to do the cutting? That poor tool...

            Anyways, got any other tools you can use to measure the hole to make sure that its actually changed size? Some gauge pins or an internal mic? Be able to find out real quick if it was out of round or size that way

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            • #7
              Shrink fit it. Seriously. Heat it up and drop the tool shank in it. It will freeze on pretty quickly, so go full depth in one quick motion. Even a propane torch will get it hot enough to grow a couple thousandths. You might never get it out.

              I have one 3/8 Kwik 200 holder that is just a smidgeon out of spec. I got a wiggler into it that way. Sadly I crashed the wiggler a couple months later. LOL. Now I have to press it out.
              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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              • #8
                I have two tapping heads with Tormach TTS shanks and want to be able to use them both on the CNC or the drill press, so no shrink fits. Yes gauge pins would be a great idea, if I had them. I'd bet that pins this size would cost WAY more than this adapter!

                So lapping, using what for the lap?

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                • #9
                  There is slop. Just stick some Emery in a slotted rod and chuck it in a drill.
                  *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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                  • #10
                    A reamer would be better, but I expect if you had a 3/4 inch reamer you would have already used it.
                    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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                    • #11
                      Originally posted by garyhlucas View Post
                      So lapping, using what for the lap?
                      Piece of round stock turned slightly under and charged w/ compound ?

                      In the absence of lapping compound, something to hand that is abrasive. Rubbing compound, valve grinding paste?

                      Maybe bluing beforehand, then a light touch, followed by visual inspection to determine where contact occurs and then paying attention to this localized area?
                      Last edited by EddyCurr; 12-02-2019, 10:51 AM.

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                      • #12
                        an hone like and Sunnen would be the best way to go. that said Hot saws and tool holders never a good thing if there not hard before the they will be after in spots and small. wood dowel rod cut a slot in it with hacksaw and use emery. Bob I bet if you tried a reamer it would not cut and you would kill the reamer Ken

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                        • #13
                          Originally posted by ken View Post
                          an hone like and Sunnen would be the best way to go. that said Hot saws and tool holders never a good thing if there not hard before the they will be after in spots and small. wood dowel rod cut a slot in it with hacksaw and use emery. Bob I bet if you tried a reamer it would not cut and you would kill the reamer Ken
                          An amazing number of tool holders I have found are NOT as hard as you would think. Besides I have carbide reamers for those sizes where I am most likely to need them, although I mostly use the carbide reamers on specialty aluminum parts. A file would likely tell you how hard the tool holder is, but I figured Gary would likely know that and most likely own a file.

                          Gary, Have you considered just making some TC tappers for different machines. I've made several now. The Tormach one is really nice (I own one) but a simple cross pin design with slots works great. If its going to be a direct tool holder or in another tool holder in a machine the OD has to be on size, but if you are going to hold it in a collet that can be tightened down as needed it just has to be pretty close to size. The bore for the collet chuck can be a little sloppy. 1-2 thou over size is good. It just needs to be concentric with the OD. EVERYTHING else can be sloppy. Really. It will self correct as the tap starts. I make them in two setups on the lathe. For making one to go on the Tormach I also make sure the register is perpendicular by doing the OD of the shank, bore for a cheap collet chuck, and register and clearance trepan in one setup. Then I flip it end for end and bore out the larger clearance for the springs and cut the internal slot for the retaining ring. Over to the mill to pop out the pin slots in a collet block. For those on the Tormach I do try to get the 3/4 shank size spot on by letting the part cool before making the finish pass to final diameter. I use a PDB on the Tormach that's adjust out of spec to hold with larger cutting tools. Undersize might slip and over size might be hard to install. If I was using a hand tightened collet it wouldn't matter. If you want to really have some fun make one out of stainless. I did with my first one, and I still use it. Also because stainless galls a press fit retention cap for the springs may never come out. LOL. I make them out of 1144 now. Very easy to turn and plenty strong enough. Heat treatable if I felt it was necessary.

                          Last edited by Bob La Londe; 12-02-2019, 01:45 PM.
                          *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

                          Comment

                          • #14
                            Originally posted by garyhlucas View Post
                            ... In cutting it with a carborundum wheel it got very hot and I tripped the circuit on the table saw. So I finished using a 4-1/2" metal cutting diamond wheel on the hand grinder. ...
                            Hey man,
                            your shop, your rules.
                            I'll watch from the end of the driveway.

                            -Doozer

                            DZER

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                            • #15
                              Originally posted by Bob La Londe View Post
                              There is slop. Just stick some Emery in a slotted rod and chuck it in a drill.
                              This, got it done. Took way more grinding away than I ever would have thought. About 1/2 hour and changed the emery cloth at least six times!

                              My Tormach tapping heads are not tension compression. They are geared auto reversing and back out at twice the speed as going in.

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