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OK, here's the deal- set true chuck

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  • #16
    yes. but its a pain, especially if you want to glue them on. every glueing you do will have a different thickness. and dont forget deburring the edges, which is a pain in itself.

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    • #17
      Originally posted by rogee07 View Post
      I'm always looking for the easy way, which often ends up taking longer than doing something the right way. So let me ask this question. Would you be able to increase the parallelism of a set true chuck by inserting shims between the backing plate and the chuck body?
      Good point. I have separated some mounting platez from chucks and found brass shim stock. I was surprised.

      I would suggest you not do that. Dount shim the chuck into place. JR
      My old yahoo group. Bridgeport Mill Group

      https://groups.yahoo.com/neo/groups/...port_mill/info

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      • #18
        Originally posted by rogee07 View Post
        I'm always looking for the easy way, which often ends up taking longer than doing something the right way. So let me ask this question. Would you be able to increase the parallelism of a set true chuck by inserting shims between the backing plate and the chuck body?
        That seems like the hardest of hard ways to do the job, when you can just take off the chuck (which you are going to do anyway) and then turn the backplate to a true condition.

        Originally posted by Bented View Post
        There are several approaches, one may solve the root problem or treat the symptoms.

        Hobbyists are often very concerned with accuracy and repeatability which are two different things. Making an accurate part (many make just 1 or a small number of parts) is easily done if time is not a consideration as most claim. Someone such as yourself are more concerned about the machine being “correct” then actually making the part accurately.

        The hobbyist method is, as you mentioned, to first determine the root cause of any inaccuracy, this includes much pulling of hair.
        Then devise home brewed methods of correcting it such as grinding the spindle nose in place, turning the back plate in place, grinding the hard jaws in place and so on, this may take weeks or indeed months. This costs little money yet a good deal of time.

        In an operating machine shop if a single part needs to be made you simply treat the symptoms and make the part, repeatability is unimportant when making one part. If producing 100 parts per hour you do not have the luxury of painstaking setup or even measuring each part. In this case repeatability is paramount, if the process will not repeat then the machine issues must be addressed using the same methods as listed above. This may include buying a new machine or hiring a company that does nothing but correct spindle or chuck errors in place, this is often done in 2 days or less but is a bit costly for a hobbyist (-:
        I think you are taking the typical attitude of a "professional" toward "home shop Harry", which is one of contempt and disdain. ("hating on them"). Kinda makes me wonder why you stick around.

        Yes, many hobby folks seem to be overly concerned with details, while at the same time ignorant of facts. Not all, however.

        I laugh when I see folks very concerned with getting the paint color on their "restoration" of an SB 9" just perfectly matching the "original factory color", while there is a 30 thou wear ridge on the bed of the machine, and every feed screw in it is worn paper thin..

        Also when work in the chuck is not held true, and the first assumption of "home shop Harry" is that "the spindle is bent". Apparently he knows the name "spindle", and has the vague idea that a bend in it is bad and could cause the problem, so that is what he focuses on.

        However, there are "mere hobbyists" who can smoke "professionals" at toolmaking, production, machine rebuilding, etc. Not all of those were ever professionals, and a number of them are on this forum.

        One fun fact is that suppose two people make a particular part. One is a home hobbyist who makes a "to-print" replacement on well-restored equipment in his personal shop.. The other is a new machine shop hire, who makes the part to "commercial tolerances" on a trashed Bridgeport after having a malt liquor for lunch. Both take about the same time to make it.

        Well then.... if a reporter were to describe the two parts, one would be a "professionally made part", and the other would be a "home-made substitute part". I will leave it to you to figure out which is which, as "an exercise for the student". And let you decide which part is likely to work.
        Last edited by J Tiers; 10-04-2020, 11:36 AM.
        1601 2137 5683 1002 1437

        Keep eye on ball.
        Hashim Khan

        If you look closely at a digital signal, you find out it is really analog......

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        • #19
          I cannot believe that checking and skimming the backplate would prove to be such an difficult task for the OP. Why on earth does he bother to have a lathe anyway?

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          • #20
            Originally posted by J Tiers View Post


            I think you are taking the typical attitude of a "professional" toward "home shop Harry", which is one of contempt and disdain. ("hating on them"). Kinda makes me wonder why you stick around.
            There is much humor to be had here (-:

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            • #21
              Originally posted by Bented View Post

              There is much humor to be had here (-:
              Yah.... there is a drought, though.... much of it is dry.

              It's often fun to just act like you take it literally and see what happens..... 😁
              1601 2137 5683 1002 1437

              Keep eye on ball.
              Hashim Khan

              If you look closely at a digital signal, you find out it is really analog......

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              • #22
                Many a true word is spoken in jest!

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