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  • Collet Chuck Runout

    I bought a 5C collet chuck for my Logan 922 from Ebay. Here's the chuck. https://www.ebay.com/itm/5C-Collet-C...72.m2749.l2649

    I trued up the back plate and made the necessary relief cuts to make it fit. There is a slight interference fit between the chuck and backplate - both the recess on the chuck and the protrusion on the backplate measure 3.741".

    With a piece of drill rod in a collet, I'm getting about 0.003" runout. Is this acceptable for a relatively low-end chuck, or should I keep trying for better? My runout on the lathe spindle looks to be less than 0.0002" on my 0.001" indicator.

    All input is appreciated. Thanks!

  • #2
    Drill rod often isn't round. Try the shank of an end mill in the collet.

    -js
    There are no stupid questions. But there are lots of stupid answers. This is the internet.

    Location: SF Bay Area

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    • #3
      What's the runout on the back plate alone? Check the runout at the collet chuck taper--Not with a mounted collet. You don't know if the error is the back plate, chuck or the collet. I have the same chuck with a 1 1/2-8 back plate and runout at the taper is near zero (barely moves the needle). It wouldn't be worth setting up the TP grinder for what it's out.

      By the way, "Toolprecision" on Ebay is CDCO.

      Added:
      After you know your chuck is spot on, mount your test rod in different axial positions to see if the error is in the rod or the collet.
      Last edited by CCWKen; 09-10-2018, 09:01 PM. Reason: Addition

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      • #4
        Originally posted by CCWKen View Post
        What's the runout on the back plate alone? Check the runout at the collet chuck taper--Not with a mounted collet. You don't know if the error is the back plate, chuck or the collet. I have the same chuck with a 1 1/2-8 back plate and runout at the taper is near zero (barely moves the needle). It wouldn't be worth setting up the TP grinder for what it's out.

        By the way, "Toolprecision" on Ebay is CDCO.

        Added:
        After you know your chuck is spot on, mount your test rod in different axial positions to see if the error is in the rod or the collet.
        Thanks. I'll check the backplate alone and the runout on the chuck taper.

        Comment


        • #5
          Remove chuck from plate, turn the 3.471" down to 3.465" or so....reinstall chuck, grip known round and straight shaft in collet, loosen the three mounting bolts a bit, indicate shaft and "tap" the chuck true, re tighten bolts.

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          • #6
            .003 runout is too much. I wonder how they built the chuck. The TIR ought to be within .001 for anything remotely decent. One thing to check is repeatability of the mount to the spindle. Take it off and put it on a couple times and check runout each time. If the mounting won’t repeat within .0005, that’s a problem that has nothing to do with econo chucks.

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            • #7
              As Ken suggested identify and eliminate all possible sources of error. I'll add one more thing to check to his list. You machined the backing plate so it was dead nutz zero at the time. But what about when it's removed and re-mounted? If you have an exposed outer surface that you machined on the first get go check that first and remount it a couple of times to ensure it stays zeroed. From there move on to the chuck's internal locating taper and parallel surfaces that the collet seats into.


              These things will confirm that the chuck and backplate are true and consistent or point out one or more problem areas. After that it's the collets themselves. I checked all mine and actually tossed on into the scrap bucket because it was about .003 off center. And for all that folks poo-poo Grizzly the replacement I got from them was no more than a needle wiggle off true... so essentially dead on. Maybe lucky? Perhaps.
              Chilliwack BC, Canada

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              • #8
                For checking things running true I never use drill rod. (silver steel here in the UK). Use a piece of High Speed Steel cutter blank at about 1/2" diameter.

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                • #9
                  I've just got the same chuck but with D1-4 mount from CDCO on Ebay. Mine had .0015" runout on the taper socket and about the same on the cylindrical journal in the back of the chuck. 5C collet centers on front taper and back cylindrical journal, so you need both to run true in your chuck to have any luck with collet runout.

                  The chuck's fit to my spindle end and to my collets was near perfect, so I decided to take the chuck apart and see what I can do. I have found a lot of grease, dirt, rust, chips inside. Nothing was deburred. Gear teeth were not machined, but cast or forged. Gears appeared to be not heat treated. When I mounted only the back half to my lathe, it had .003" runout on the face and register diameter. There is something wrong in their manufacturing process and I think all of the chucks from this factory are defective.
                  I have approached CDCO and asked for a 50% refund and to keep the chuck. My hope is to be able to re-machine the chuck to a usable condition. This is what I am planning to do.

                  I am getting an indicator with a long needle so I can reach the back cylindrical journal. I will machine down the register diameter of the back part of the chuck and probably will not touch the face. After that will re-assemble both halves with light torque on screws (need to replace the screws, the originals are only 8.8 grade and are too short) and tap the front part to a perfect alignment on the back cylindrical journal. Now it is the time to check TIR on the front taper and grind it if needed. I am not planning to put back the 2 roll pins between the front and back halves - they are not needed.

                  So this is my plan - what do you think about it? I know it is a lot of work, but I have time and I am getting a great satisfaction from being able to convert a pure junk into a usable product.

                  Comment


                  • #10
                    Sounds like a good plan of action to me. Once you get the chuck running true, you will get a lot of use out of it. Check each and every collet for runout. On mine, some Hardinge, South Bend and other name brand collets had a surprising amount of runout when the 5C taper was running only .0001 or .0002 out. Some of the cheap import collets were very true, with some having varying degrees of runout. I used gage pins in the collets, as there were many different sizes.
                    Kansas City area

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                    • #11
                      I bought one from CDCO and tried everything and still had excess run out and it was the hole for the collet that was off center, after truing with a boring bar it now has .0005” run out!

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                      • #12
                        All these runout and poor machining reports is making me happy that I did my own from scratch......
                        Chilliwack BC, Canada

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                        • #13
                          Originally posted by 1200rpm View Post
                          Remove chuck from plate, turn the 3.471" down to 3.465" or so....reinstall chuck, grip known round and straight shaft in collet, loosen the three mounting bolts a bit, indicate shaft and "tap" the chuck true, re tighten bolts.
                          This will work but you'll probably have to tap it around with each different size collet you use.
                          Indicate the run out on the taper, tap it around until you get zero and then try a collet with a gage pin or as mentioned the shank of an end mill and see what you get.
                          Unless you buy Royal or Hardinge expect up to .003 in runout.

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

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                          • #14
                            Originally posted by BCRider View Post
                            All these runout and poor machining reports is making me happy that I did my own from scratch......
                            Well, this what you get when you buy a Chinese copy. Bison or any other name brand chuck lkke that will cost you close to 1k or more.

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

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                            • #15
                              Well she's done and I have seen the error of my ways. Its now giving me no measurable run out on the taper of the chuck, and about 0.0003" on an endmill shank held in a Shars collet in the chuck.

                              While I'd like to blame my difficulties on some kind of manufacturing defect on the part of some far-east manufacturer, a more accurate description would be summed up as operator error - I Bozoed the backplate.

                              I mounted the chuck on my Logan lathe with a threaded spindle. When I trued up the back of the backplate, I just spun the backplate on backwards without making sure it was seated properly on the spindle. Once I figured out what I did, I recessed some of the threads on the front of the backplate so it would seat properly on the spindle, retrued the back side of the backplate, then flipped it and recut the front surfaces. I was lucky in that there was plenty of meat on the backplate to allow me to recut what I had to.

                              I thought I watched enough youtube videos before I started, but I guess not!

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