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Sanou 4 Jaw Chuck Back plate Question

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  • Sanou 4 Jaw Chuck Back plate Question

    I bought a PM 1022v metal lathe for my garage. It came with an additional Sanou 4 jaw chuck with the back plate that fits the PM1022 spindle attached. OK, I can mount it on this lathe, however, I'd like to disassemble, clean, and lubricate the chuck first. Most back plates I've seen so far, are attached to the chuck by recessed cap screws or similar. However, this back plate, while holes do exist, some with threaded bores, others blind bottomed holes, does not have any apparent screws or bolts holding the back plate onto the chuck. Yet it is very firmly attached. Does anyone have this particular chuck/lathe combo and been able to disassemble the chuck for cleaning/lubrication? Haven't run a lathe since I was 16 years old, some 49 years ago so things are different now.
    S E Michigan

  • #2
    Might there be screws from the front that are mounting the chuck? The holes for those might be blind holes, since there are some already apparently there.
    1601

    Keep eye on ball.
    Hashim Khan

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    • #3
      No front screws that I could see. Removed one of the jaws to see if behind that, but only the threaded jaw screw. Maybe I'll get some pics when back in the garage shop and post. Most confounding, but someone had to mount this spindle fitting back plate...just need to figure out how without resorting to pounding.
      S E Michigan

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      • #4
        Originally posted by OaklandGB View Post
        I bought a PM 1022v metal lathe for my garage. It came with an additional Sanou 4 jaw chuck with the back plate that fits the PM1022 spindle attached. OK, I can mount it on this lathe, however, I'd like to disassemble, clean, and lubricate the chuck first. Most back plates I've seen so far, are attached to the chuck by recessed cap screws or similar. However, this back plate, while holes do exist, some with threaded bores, others blind bottomed holes, does not have any apparent screws or bolts holding the back plate onto the chuck. Yet it is very firmly attached. Does anyone have this particular chuck/lathe combo and been able to disassemble the chuck for cleaning/lubrication? Haven't run a lathe since I was 16 years old, some 49 years ago so things are different now.
        A little searching found https://markswoodchips.com/precision...2v-lathe/.html where it appears the backplate is supposed to be held by bolts from the back.



        Might the bolts have been removed by accident? Chucks often have a VERY tight fit to the backplate, and it might be stuck on the spigot???? Just guessing without the pictures.
        At the end of the project, there is a profound difference between spare parts and extra parts.

        Location: SF East Bay.

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        • #5
          Danlb,
          Yes Sir!!! that is exactly what I have, with the same spindle mounting studs, but minus the bolts holding it to the chuck. The 3 spindle mounting studs and nuts were loose in the sealed Sanou box, and there are no other bolts in the back plate like the hex bolts in your pic. I am thinking that your comment about the tight fit is the most likely situation, but thought I'd post the question before that step. I think I will try tapping the back plate with a dead blow hammer to see if it comes apart, there being absolutely no other visible means of attachment. Thanks for the suggestions.
          Gary
          S E Michigan

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          • #6
            Quality control seems to have been lacking..... it is a good thing that you did not mount the thing and spin up to a good speed, as the whole chuck and work WOULD have flown off the mount in short order.

            I am not too impressed with the close up pics, either.... Notice the way the clearance flats are not milled down to the same level as the turned portion.... so the mounting bolts are forced to have their heads bent off at an angle. Not the best for longevity, but probably sorta OK if they are only tightened one time.
            1601

            Keep eye on ball.
            Hashim Khan

            Comment


            • #7
              JT. by gosh you are right. Hadn't noticed that but looks to be several thousandths difference there. The one at about 2 o'clock in the pic also seems cocked over or it is just the angle of the photo. These pics came from markswoodchips.com from a few years ago I think. I noticed that the spindle mounts are still the same but his version of the PM 1022 did not come with the QCTP installed as they now do as standard. Your point about the chuck letting go if spun up is right on. I can't get back to this until tomorrow night but I have an appointment with that 4 jaw and a dead blow hammer to confirm it is just friction fit. I wouldn't have mounted it without cleaning anyway but not sure someone else would have and suffered some problem. As the chuck was in a sealed Sanou box from the manufacturer, it is likely that the seller's machine order specs include the back plate mounted to the 4 jaw. They just put it in the crate with the rest of the extras and ship it out. I'll do a follow up on my results after the hammer session tomorrow. Thanks for the comments. Gary
              S E Michigan

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              • #8
                Well, it took all week to get back to the garage and that new in the box 4 jaw Sanou chuck. JT you were correct. The back plate was just mounted without being secured by anything except a tight fit. A tap with a dead blow loosened it. Found the same "ledge" but measured about 0.002". Must be the corners are cut using a mill but they are not getting down to the turned surface. Live and learn I guess.
                S E Michigan

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                • #9
                  I noticed the numbers on the bolts holding the backplate and chuck together, they are 4.8. This grade is what I would call HTC (high tensile cheese). Bolts with 10.9 or 12.9 are three times the strength. The other fixings from the backplate to the flange on the spindle may also be low grade alloy, I would make replicas out of something strong, and get some decent nuts as well.

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                  • #10
                    While I would, for several reasons, use higher grade parts.... My suspicion is that if there were any real need for higher strength, the "event" that causes that need would tear up the rest of the machine before all those bolts sheared.
                    1601

                    Keep eye on ball.
                    Hashim Khan

                    Comment


                    • #11
                      Hmmm, keen observation on the bolts and mounting hardware. This is a 10x22 and pretty light duty, but those mounts in better steel might be an interesting project. Would they need to be hardened at all? Not sure what steel would be good for this application. The other thing is I'd have to figure out how to cut the flats since I don't have a mill.
                      S E Michigan

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                      • #12
                        Just buy them . They should be available in a better grade if you determine the size, which looks to be 6 mm or so.
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #13
                          Making replicas of the spindle to backplate in better steel should not be difficult, you can produce the spanner flats with a file.
                          Perhaps someone could recommend a decent grade of steel to make them from which won't require any subsequent heat treatment, the specs in the UK would be en19t or en24t, but I'm unsure what the USA equivalents are.

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                          • #14
                            Did I miss something? Those blind holes were mentioned in the first post and not mentioned again. So here's my $.02. The blind holes are for jack bolts that push the back plate off the main body. look at posts 9 and 10 on here: http://bbs.homeshopmachinist.net/threads/67015-D1-chuck
                            Last edited by Dave C; 07-29-2018, 02:13 PM.
                            “I know lots of people who are educated far beyond their intelligence”

                            Lewis Grizzard

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                            • #15
                              Dave, You missed posts 4 through 8. The blind holes are for bolts to hold the backplate to the chuck body. The "threaded bores" are for the studs that hold the backplate to the spindle.

                              Disassembly of the chuck body uses the screws on the back of the chuck body just inside the central bore.
                              At the end of the project, there is a profound difference between spare parts and extra parts.

                              Location: SF East Bay.

                              Comment

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