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  • 3 jaw chuck run out

    all righty now , I know I will get a little critisism out of this , but here goes....I purcahsed a 3 jaw Wholesale Tool(import, I should know better, but can't afford a buck /cushman right now) D1-6 chuck on clearance for 100 bucks as is ....I figured it got returned because of exessive runout....and I was right ...6-7 thou...checked with several different diamiters always the same jaw high /low & one in between, the same amount. I then put a 5 thou shim on the low jaw , and it got everyting under 2 thou , which is totaly acceptable for most of the stuff I do on a regular basis. Now how do I fix it permanently/correctly????the only thing I can come up with is using a tool post grinder to true up the jaws.....am I correct in my thinking , or is there another way????Thanks in advance , Shawn

  • #2
    No Criticism from me
    Before you go to grinding them, that seems to have it's own set of issues.

    If the jaws are not numbered, perhaps even if they are try switching them and see if it improves anything.

    First though, tear it apart, check for burrs and clean everywhere, including the back plate.

    .006 - .007, have seen worse!

    Ken

    Comment


    • #3
      I clamp a piece of steel round stock with a hole in it.... in the back of the jaws and then use a tool post grinder to true up the jaws. Mark the steel so it aligns with the #1 jaw (or any jaw for that matter as long as you mark it). I then clamp the same piece of steel with the hole in the middle in the newly trued up faces (aligning it with the same jaw) and clean up the back end portion where the piece was clamped to start.

      Once done...make sure to dissassemble the chuck and clean it very well. The grinding swarf will chew the chuck to pieces if left inside. Oil it well and then check for true.

      Cheers
      mac.

      Comment


      • #4
        From what you've said, that is a logical conclusion. Be sure first that you can mount and unmount the chuck and it always comes to the same point, that is the same jaw would need the same shim to bring the runout close to nil.

        Once you have determined that to be the case, confirm it one last time with a short piece of pipe mounted near the back of the jaws. This gives the jaws something to close on and keeps them in the same position they would be in for any workpiece that's being held. (for the most part that is, there are other variables).

        Grind the jaws, removing only enough material so that each jaw has at least been touched by the grinding stone. Open the jaws only enough to pull the short pipe piece towards the front and close the jaws again. Finish the grinding job.

        Very important now- take the chuck apart and clean it well to get rid of all the grindings that will undoubtedly be lodged in the scroll and jaws.
        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

        Comment


        • #5
          Shawn,
          In addition,
          A quote from "Mcgyver" just about says it all.
          " Personally I don't care much whether its .003 or .006 - If it needs to be exact, use a collet or 4 jaw, if not whether its .003 or .006 usually doesn't matter. Remember though everything turned with one set up will be perfecty concentric - ie the lack concentricity is only between the turned surfaces and the surfaces gripped by the jaws. If you plan your work so that the turned and bored surfaces are done at one set up it is a convenient chuck to use."

          Comment


          • #6
            That was the first thing I checked no # on the jaws, pulled one of the top jaws off and it had a #1 on the mating surface , the master jaw had no # , so I reversed it and undid the next jaw, same thing , it is also #1, and the same on the 3rd jaw, it is also #1, So I have some labling to figure out as well...What di I expect fo a 100 bucks for a 10 " chuck....And I fully agree with Mcguyvers comment ken...the only problem I have right now is I don't have a 4jaw or collets ..So I have to make do with what I have , and if everything I turned was from scratch It would not be a problem, but sometimes I have to re-chuck stuff and then it's a problem... I guess I will just keep some shimstock handy...Thanks again guys, Shawn

            Comment


            • #7
              just use it.

              I've never understood this 3 jaw runout concern in the sense that even the good ones are going to be 2-3 thou out. For what class of work is 3 ok but 7 not? imo, the three jaw is either for very rough work where it doesn't matter whether its 3 or 7 OR for work where everything is turned at one setting (thus ensuring perfect concentricity)


              when you need concentricity to a work holding surface or repeatability, use a collet, 4 jaw or centres....not a cheap or expensive 3 jaw

              Ken, that's tooo funny, just typed that, well at least i'm consistent
              in Toronto Ontario - where are you?

              Comment


              • #8
                I understand Shawn, we all can spend only so much at a given time, sound like you have a grip on what's needed.

                Been mentioned more then enough but once more won't hurt
                Still, if you have not, completely disassemble, clean, lightly oil, and looking for burrs as well.

                When chucking, mark a spot on the stock that aligns itself with a given jaw, then, when re-chucking orient it to the exact same place, this will at least limit some of that re-chucking difference.

                Let us know how it ends up.

                Ken

                Comment


                • #9
                  Originally posted by Mcgyver
                  just typed that, well at least i'm consistent
                  And there's a lot to be said for that

                  Comment


                  • #10
                    If Your bargain chuck came with a D1-6 backplate sepperate from the actual back of the chuck, maybe You could turn it into a set-true style .

                    Steve

                    Comment


                    • #11
                      run out in chuck

                      I have a chuck that had run out it. It is a 10 inch non adjustable chuck. I removed the jaws and checked on the back side of the jaws. Mine has a plate that locates the jaw location in the groove that it bolts in the chuck. The plate is held in with a screw, I remove the screw and tapped the plate out and turned it 180 degrees on each jaw until I found through different combinations that I could get the chuck running within a few thousands. I have never seen a chuck made this way, but this one is. I do not know if your chuck is made this way or not, but its worth a shot.

                      Comment


                      • #12
                        Use a key ring

                        I use a key ring at the back of the chuck jaw just behind the offset when grinding. It is small enought that you don't have to reposition.

                        Comment


                        • #13
                          Its new after all.

                          This is the OP.

                          Originally posted by shawnspeed
                          all righty now , I know I will get a little critisism out of this , but here goes....I purcahsed a 3 jaw Wholesale Tool(import, I should know better, but can't afford a buck /cushman right now) D1-6 chuck on clearance for 100 bucks as is ....I figured it got returned because of exessive runout....and I was right ...6-7 thou...checked with several different diamiters always the same jaw high /low & one in between, the same amount. I then put a 5 thou shim on the low jaw , and it got everyting under 2 thou , which is totaly acceptable for most of the stuff I do on a regular basis. Now how do I fix it permanently/correctly????the only thing I can come up with is using a tool post grinder to true up the jaws.....am I correct in my thinking , or is there another way????Thanks in advance , Shawn
                          Shawn.

                          There is no need here, so far as I know - or care - that requires you or anyone else to get or have the approval of anybody (else) for anything that you buy or do or where anything is sourced from.

                          It follows then that there is no need to explain or apologise either.

                          From what I can see, that should be a good chuck - period.

                          The chuck should not need regrinding as it is - for all intents and purposes - new.

                          Here are the specs for new chucks - Chinese - so check them out.





                          The "acceptable" figures are in millimeters - 0.001" is about 0.025mm.

                          It seems that the chuck the OP has is not too bad after all.

                          I agree with Mcgyver's advice and sentiments - just accept is for what it is - pretty good really - and get on and use it "as is".

                          Comment


                          • #14
                            Clamp with the master and grind/bore the jaws true.After that check a few diameters for runout.If there isn't any it's cured.If it still has runout,especially inconsistent runout then there is no fixing it.

                            I will go along with a fourjaw being better,but only so far as the fourjaw not being bell mouthed.They do wear out too.
                            I just need one more tool,just one!

                            Comment


                            • #15
                              Originally posted by Mcgyver
                              just use it.

                              I've never understood this 3 jaw runout concern in the sense that even the good ones are going to be 2-3 thou out. For what class of work is 3 ok but 7 not? imo, the three jaw is either for very rough work where it doesn't matter whether its 3 or 7 OR for work where everything is turned at one setting (thus ensuring perfect concentricity)


                              when you need concentricity to a work holding surface or repeatability, use a collet, 4 jaw or centres....not a cheap or expensive 3 jaw
                              it matters because it is annoying.

                              it matters if you would like to get all the work "inside" the piece you start with, and that's close to net size.

                              Did I mention that it is annoying?

                              Pretty much like crosslide slop. Yes, it doesn't really matter in most situations, but it is annoying, a source of calculation errors, etc.

                              And it's annoying, of course.

                              Go ahead and grind.

                              But, turn some plugs to fit the top jaw holes, and close the jaws on a ring grabbed by the plugs. (for thos having solid jaws, drill holes with a 1/8 masonry bit or other carbide in highest jaws)

                              Closing on a ring at the heel may not matter in this particular case, but if the jaws are worn, it doesn't load them the way they get used, and will leave the jaws bellmouthed after grinding. (method originated with Rich Carlstedt)
                              Last edited by J Tiers; 11-05-2009, 09:57 AM.
                              CNC machines only go through the motions.

                              Ideas expressed may be mine, or from anyone else in the universe.
                              Not responsible for clerical errors. Or those made by lay people either.
                              Number formats and units may be chosen at random depending on what day it is.
                              I reserve the right to use a number system with any integer base without prior notice.
                              Generalizations are understood to be "often" true, but not true in every case.

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