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3 jaw lathe chuck

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  • 3 jaw lathe chuck

    First. I went back and read the 3 to 4 year old thread on "cleaning and lubing chucks" and even the post I made noting I had 8 lathes to start thinking about cleaning the chucks. :-) Well the time has finally arrived and I started on the first one. Got the chuck body off the back plate ( D 1-6 ) I think. and the crud out of that space. Then I started looking for how to get access to the scroll plate and the gearing. HA! I couldn't even find the place where the two pieces even separated until I got the light in a particular place and still no idea of how to separate the two. Do I realy need to get at the back of the scroll ?? The front can be cleaned ( with considerable difficulty ) without getting it completely out but access through the jaw slots is cramped. :-) So! here is pic of the Atlas chuck in question.
    How do I get it apart or should I fergetit ? :-)
    ...lew...

    Stupid cell-phone camera pix. I had that pix rotated in the file I linked but the internal info wont let it stay that way BAH!
    Last edited by Lew Hartswick; 01-29-2018, 03:39 PM. Reason: add note on pix.

  • #2
    Support the upper part off the ground from center hole and press the lower part apart via bolts screwed partially to those holes.

    Cleaning the backside of the scroll is lot less important but once in a decade is not bad idea.
    Location: Helsinki, Finland, Europe

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    • #3
      That looks a lot like the BTC chuck I disassembled (and posted about) last week. It's got a lot of pictures. The center screws go through the top half to screw into the bottom half. I believe mine were 1/4-20 thread. If you support the top half by putting a large socket or drift in the central 1/5 inch hole you should be able to force the halves apart by putting pressure on the 6 center screws. Make sure the center screws are screwed in several turns so they don't deform under pressure.

      http://bbs.homeshopmachinist.net/thr...e-BTC-Zero-Set

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

      Location: SF East Bay.

      Comment


      • #4
        I don't see the chuck pinions in your picture. Did you remove those already? They need to come out first or the inner back plate and scroll won't budge. Once those are out you can typically thump the back edge down on a scrap board and the impact pushes the scroll and the back plate out the rear of the body at least far enough that you can then thump it down against some smaller scraps that only catch the edge of the body.

        If you use screws or a drift to push the scroll and inner retaining plate out do so very evenly and walk them out with small taps. They get wedged in the body bore very easily with any angle at all.
        Chilliwack BC, Canada

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        • #5
          Originally posted by BCRider View Post
          I don't see the chuck pinions in your picture. Did you remove those already? They need to come out first or the inner back plate and scroll won't budge.
          If it's designed like mine, the two halves separate at the pinion hole. The pinion will not come out till the halves are split. Can't tell from this picture.

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

          Location: SF East Bay.

          Comment


          • #6
            OK I'll see tomorrow. I think it's made like the one danlb posted. It's an Atlas and had a D type back but that came off easy . I thought the 6 screws around the center must be what holds it but couldn't find any way to hold the right part to do any "taping".
            Follow-up tomorrow afternoon . Promise. :-)
            ...lew...

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            • #7
              Does that have 4 screws around the base to adjust the position? It looks like the the Buck set true as well as the BTC Zero set.
              At the end of the project, there is a profound difference between spare parts and left over parts.

              Location: SF East Bay.

              Comment


              • #8
                When you finally get the thing apart, file a tiny chamfer on the external joint, so that in the future, you can see where the split line is. Also mark the main parts as they come apart so they go back together the same way. Manufacturers often finish grind the outside after assembling the main parts and the joint line is hard to see.

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                • #9
                  Originally posted by old mart View Post
                  When you finally get the thing apart, file a tiny chamfer on the external joint, so that in the future, you can see where the split line is. Also mark the main parts as they come apart so they go back together the same way. Manufacturers often finish grind the outside after assembling the main parts and the joint line is hard to see.
                  No need to do the chamfer now that I know how and where it comes apart, :-) Every thing worked fine after I finally found a piece of turned stock to fit the hole and support the front while tapping on the three longer socket head screws I used in place of the 6 that held the two parts together. As to marking for re-assembly, Not needed as there is only one pinion so the parts can't go together any way but one.
                  danlb; yep those do the job I remember doing it a long time ago. I got 3 of chucks done this morning only 5 more to go :-) The adjustment got faster the more I did, only 2 times around on the last one. :-)
                  The grease was pretty well dried out, actually caked on one of them. Used kerosene and "Brakeclean" to clean up and a spritz of aerosol lithium grease to help insert the scroll and a Mobile Synthetic grease on the pinion and gear. By the time I get all 8 done I should be almost an expert on this. :-) Maybe I should "hire out" to do them. :-) There was not as much junk in the scrolls as I thought there would be. But plenty in between the chuck and the backplate. A pix of one disassembled. Any one know how to modify the EXIF data so I can make the pix show up rightside up ?? Silly cell-phones cameras insist on using wrong way up.


                  ...lew... Hey this one came out right. :-)

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                  • #10
                    It always interests me to see the variety of construction methods for a simple thing like a chuck.

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                    • #11
                      Originally posted by old mart View Post
                      It always interests me to see the variety of construction methods for a simple thing like a chuck.
                      :-) These chucks aren't quite so simple as all that. :-) Now a 4 jaw is a bit "simpler" and even a collet I would consider simpler. :-)
                      ...lew...

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                      • #12
                        Now to figure out whether BTC made them for Atlas or the other way around. Two piece jaws on that one? Are they standard or closer to what's shown in this PDF?
                        http://www.btcchuck.com/catalog/Catalog_Page_09.pdf

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

                        Location: SF East Bay.

                        Comment


                        • #13
                          A Logan we had at work had a chuck like this that split in the middle in the same way. But it was all held together with screws from behind instead of from the front.
                          Chilliwack BC, Canada

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                          • #14
                            Originally posted by danlb View Post
                            Now to figure out whether BTC made them for Atlas or the other way around. Two piece jaws on that one? Are they standard or closer to what's shown in this PDF?
                            http://www.btcchuck.com/catalog/Catalog_Page_09.pdf

                            Dan
                            Sure looks lie the same parts arranged in the same fashion. :-)
                            ...lew...

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                            • #15
                              The 6 inch BTC has two part jaws that are not "standard". That's why I'm hoping to find other models that share the same parts, especially the jaws. Would you mind checking yours against the spec in the PDF?


                              The link I sent shows the key for the 6 inch master jaw sticking up in the middle of the jaw. Standard design is to have the groove in the bottom, and key in the top. The width of the master jaw is 0.736 inch, and the distance between the center of the holes is 1.686 and they use a 5/16-18 thread.

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

                              Location: SF East Bay.

                              Comment

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