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I hate tapered pins!

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  • I hate tapered pins!

    Been a while since I posted here. Stop in to look around now and then but busy much of the time.
    Recently I picked up a 10"x 36"(?) 195X Monarch CCK lathe for $250. Both a 3 and 4 jaw chucks, steady rest and taper attachment. Reason it was cheap is because the last guy knew nothing about rigging and dropped it TWICE! Both times if fell forwards onto the shift levers and hand wheel. Also bent the carriage reversing shaft and the clutch engaging shaft-the square one. Trying to get the levers off to repair has been a night mare of dealing with tapered pins not wanting to let go/ back out no matter what I do. The big ends are only 1/4" so there is not enough to drill and tape for slide hammer. Add to this that none of them are in an easy plane to follow with a drill and I have come to wish who ever thought up specified taper pins in this build a lot of ill will!!

  • #2
    I assume the taper pins were or are holding whats left of the carriage handwheels on?, try a little heat on the boss and shaft with a puller applying tension on the boss belt the thin end with a short 1/8 inch parallel punch, worked for me once taking a broken hanwheel boss off the apron.
    Failing that and drilling becomes the only option you may have to make a guide that can be clamped or tack welded on so you can get a hole through then ream with a taper reamer to remove the pin, it usually gives up before you reach size leaving a shell on the reamer, can you get a mag drill on the top of the apron?
    Good luck
    Mark

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    • #3
      The hand wheel was the easy part to get off since I could turn it until the pin was straight up and down. The problem is with the shift levers. Pins at just 0.250 on the big end. Only 1 was horizontal. The rest are at odd angles and close to or beside something else so getting a straight shot at them is not possible. Heading is always the first thing I do to loosen parts!

      Will take a picture later.
      Thanks!
      mark61

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      • #4
        Drill, tap, screw in SHCS, and then use a slide hammer.

        oh.. I hate the SOB's also. My Polamco is covered with them. The "blind" are easy - the are all tapped for an extraction bolt. The "through" pins are not, and both side are messed up by the prior owner so you can't tell even the direction of the taper - careful flush grinding then dye will often show the outline on both sides..

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        • #5
          Hi mark61
          It appears that the IDIOT who dropped the lathe on it's side has part sheared the taper pins so that they now have a step in them making them impossible to drive out.. Would it be possible drill a pilot hole with a "Dremmel Tool".
          Keep us posted on progress.
          Eric

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          • #6
            Many times the get buggered up on the small end and are a real pain to get out. grind the pin end flat before using a pin punch to drive them out. I have also drilled them out. Many times its hard to get a drill bit and drill motor close as it hits the casting, so I braze a longer extension to the drill or buy a pulley drill so you can keep the drill motor (hand power drill) running straight and drill it out. Once the center part of the pin is gone it scrinks in and can loosen up. As you said its a real pain. Take your time and stay cool.....:-) Riich
            Last edited by Richard King; 11-01-2013, 09:36 AM.

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            • #7
              Taper pins themselves are not so bad. They work.

              The problem is the spawn of slime who drill the holes in at any old angle, which the reamer of course follows, so the pins might be at nearly any angle, not perpendicular and not through center. Not much help if you have trouble finding the other end.

              Then when the assembly is, as is sometimes done, "cleaned up" with lathe or a good filing job, there is almost no trace of the pin. Good luck.

              So long as you find the small end, they drive out, in general. Not so much if the hole is not accurately tapered, if swelled up on the small end it may "peen in place" and not want to move. or if the pin is partly sheared, same thing.

              With Monarch, I wouldn't expect that. But it's super easy to peen the pins so they refuse to come out. Then the more work you do, the tighter they get.

              Those problem are also present with straight pins, though. And straight pins may be hardened (hard to drill).

              At least if you can shift a taper pin, it comes out. A straight pin may fight you all the way through.
              1601

              Keep eye on ball.
              Hashim Khan

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              • #8
                I HAVE BEEN FIXING JUNK FOR 66 YEARS.
                It sounds like you are on the right path.The first thing I do when I run across a stuck or broken pin or screw or tap or drill or nut or bolt is STOP and clear the area and clean everything up.This calms me down and gives my time to think.The worst thing I have done ,and I think we all have done it is to grab a drill or a hammer and chisel and make it worse. My favorite tool for this stuff is a high speed pencil air grinder with a 3/23 or 1/8 carbide BALL CUTTER .You say that you cant come at it longwise with a drill.In this case sometime I use a small right angle air grinder .These have a 1/4 inch collet .I have an adapter collet that allows me to put my 1/8 shank carbide ball cutter in my small right angle grinder.These small right angle grinders only go 20,000 rpm but this might allow you to carefully wallow out the pin.Ihope this helps and good luck.Edwin

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                • #9
                  I have to remove stuck taper pins routinely.Best method I have found is to drill the small end with a drill about 2/3 the diameter of the small end.Drill ALMOST all the way through leaving about one pin diameter of length left at the big end.Insert a good quality drive pin punch into the drilled hole and drive it out.Given the sizes mentioned I would try a 5/32 drill and a 1/8 punch.

                  I have also used a Mig welder to build a head up on the big end.Then used a bolt about 2" long,chopped the head off and weld it on to the build up as a pull stud.A short pipe sleeve ,washer and nut and a twist of a wrench and out they come.Sometimes they require a few taps on the small end alternating with tension on the otherside.

                  Like Jerry said,if you can get them to move at all they will most times come on out.
                  I just need one more tool,just one!

                  Comment


                  • #10
                    [QUOTE=mark61;883050] Monarch CCK lathe for $250. Both a 3 and 4 jaw chucks, steady rest and taper attachment. [QUOTE]

                    Taper pins a bit difficult? Wow too bad, I feel for you. NOT

                    Comment


                    • #11
                      Originally posted by lakeside53 View Post
                      Drill, tap, screw in SHCS, and then use a slide hammer.

                      oh.. I hate the SOB's also. My Polamco is covered with them. The "blind" are easy - the are all tapped for an extraction bolt. The "through" pins are not, and both side are messed up by the prior owner so you can't tell even the direction of the taper - careful flush grinding then dye will often show the outline on both sides..
                      How can he drill and tap the pin he's trying to remove if he can't gat a straight shot at it with a punch???

                      What I've done in the past with things that are in a bad position to drive out is get a piece of flat bar about 12" long or so, drill and press a pin in one end leaving it sticking out about 1/2" you then can hold the bar in one hand while positioning the pin over the pin you want to drive out, then you can hit the bar with a hammer as close to the pin as you can get. It's not a direct hit over the pin but usually transfers enough driving force to move the pin. Taper pins only need a slight nudge to come loose.
                      Note: you may want to tack weld the driving pin to the bar.

                      JL........................

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                      • #12
                        Originally posted by JoeLee View Post
                        Taper pins only need a slight nudge to come loose.
                        JL........................
                        Sometimes!
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #13
                          I did have a customers maintenance man helping me once and I told him what to do, and he still had issues, so I took a look. I said "hey do you have a dial vernier?. I said take it and measure the ends....he did and turned around red faced.....lol..he had been whacking the big end....
                          I tell folks when installing new ones, tap them in and don't use your 5 pound sledge. Doesn't take much to hold them in.

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                          • #14
                            When I was working as a mill wright I learned to drill them out as others have suggested. This seems (not data supported) to reduce the press fit between the pin & the hole. Don't drill all the way through to leave yourself a hole with a bottom for the punch.

                            Keep in mind taper pins allow one to disassemble and reassemble components as close as possible to their original location, so in that respect they are excellent. However, as you and others have said they can be a real PITA to remove, especially after they've been mushroomed over, or bent.

                            Concerning the ones that are in "impossible to reach" locations you may need to make a tool such as the flat bar with a pin, or remove the assembly from the lathe with a different approach so you can work on it on a bench. Others have recommended "Dremmel" or air grinders an I agree with them. One could also consider flex shaft and right angled versions that can access tight places.

                            Your main ally is patience along with persistence. Trust me I understand just how frustrating careful dis-assembly can be and I've mentally and sometimes literally cussed more than one designer. At least I learned from their mistakes and include things like threaded holes for jack screws in my designs.

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                            • #15
                              I like the idea about drilling 3/4 way down and using a punch. I sure enjoy reading this site.....thanks for making the day pass faster. :-) Rich

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