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What Do You Indicate Off Of When Tramming Mill

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  • #16
    Originally posted by dmartin View Post
    I was hoping someone here that has been using a milling machine for 40 years would say, yes if you trust the vice and table from past experience and only the head was moved it will be fine don't worry about it.
    I would say that is safe conclusion....but we didn't know about the nuances, the back issue, vise being dead on etc, so you got best practices. Only you know what you work on, but for me, the solution would be a lifting device so you could take the vise off; probably 10% of the time, maybe more, I'm taking the vise off to bolt work directly to the table or use some other tooling; angle plate, V blocks, 5c fixture, RT, diving head, tilting table etc. Not having safe access to the table would really limit things.

    If the vise just can't come off, I'd be thinking of making some disk with a block that was very accurate, scraped would be my choice. The block would register to the bottom of the vise and fixed jaw and present a horizontal surface parallel and perpendicular to those surfaces to tram to. That way tram is to the fixed surfaces you believe to be true, whereas the top of the moving jaw is a bit of a variable.

    That or one of those three legged stool things.
    Last edited by Mcgyver; 09-15-2018, 07:26 AM.
    in Toronto Ontario - where are you?

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    • #17
      At my work, I'm always removing the vise for big parts, then putting it back on for small stuff- probably several times a week. I've gotten really fast at indicating the vise in. I semi-tighten the table clamp on one side. Set your indicator on that side, then move in 'X'. Power feed makes it even easier. As the table moves, watch the indicator. Keep tapping with a soft hammer as you go to keep it on '0'. Once you get it good, gradually tighten the bolts and keep re-checking. I use a .0001 indicator exclusively, and it only takes me a couple minutes to get the vise within a tenth- assuming the vise and machine ways are that accurate.

      I told you all of that to say that I almost always move the vise out of the way to tram the head. I use a 7" diameter bearing race, and a .0001 indicator. If it's within a couple tenths over 7", it's more accurate than most mill work anyway. I would tram off of the vise jaw if: 1) I had to tilt the head to machine a part already in the vise, and 2) I had already checked the top of the vise jaw in my initial set-up to be sure it was parallel. I tend to mount my vise somewhat off center so that I can bolt a bigger part directly to the table without moving the vise, and it also leaves me a clear space to tram the head off of the table without moving the table way off center, which may not be as accurate due to wear and table sag.

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      • #18
        Originally posted by Paul Alciatore View Post
        I sweep across the table itself. But then, I don't make a habit of keeping the vise permanently mounted on it.

        I have seen rings that stand over the vise with their legs resting on the table used for this. I think they are sold by some of the tool suppliers. As to how good they are, I do not know.
        I've never seen anything like that before, any pics???

        I use a 1/2" wide x 6" long parallel to tram my mill. I ha e a bar that I mount in the spindle that is bout 12" long. I can mount the dial anywhere along the bar depending on how big a circle I want to sweep. I move the parallel along under the dial point as I rotate it around.
        I also have a 3" dia. x 1" thick disc that I ground flat. I use that sometimes. But that doesn't hang over the table very far.

        I've been looking for a ground test ring about 10" in dia.


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

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        • #19
          Originally posted by Mark Rand View Post
          I use a ventilated car brake disk. They are surprisingly flat (maybe not so surprising, since they tend to be faced with a double sided tool post). The one I got is flat to less than a tenth, and rests on the table while I sweep the indicator around.)
          I bought a 13" rotor last year at one of the local parts stores for this purpose.
          Tried to find one with out a hub but all the large dia. ones had hubs.
          I indicated it on the surface plate and found that it tapered inward about .002 but was consistent all the way around. The finish was pretty nice but still gave the dial the jitters.
          I don't think I can mount it in my lathe to part the hub off of it and I can't find any shop with a surface grinder big enough to grind it.

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

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          • #20
            Originally posted by Paul Alciatore View Post
            Nothing is ever mounted to the TOP of the vise. So, IMHO, that is not what you want to tram the mill to. Now, the top of your vise may be 100% true, but do you know that? I doubt that the top surface of any milling vise is even specified.

            The sequence is:

            1. The top of the table should be parallel to the ways/slides.

            2. The bottom of the vise should be a good, FLAT reference surface.

            3. The top of the vise's saddle, which is what a part or your parallels that support your part are mounted on, should be parallel to the vise's bottom.

            Due to the buildup of tolerances, it is not best practice to use any part of the vise for tramming the mill head. Number 1 above should be checked when the mill is new and at intervals after use. But that should be a "given" and should not have to be checked on a daily basis or even when the head is rotated and then returned to vertical.

            As I said above, you should tram the head on the TABLE's top surface. And, as I said above, that is difficult if you keep the vise mounted all the time.

            So, I suggested one of these:



            It allows you to tram to the table's top while the vise is mounted on that table.
            It looks like something you would put a burner under.

            Is there not a fourth leg??? I would have to question the accuracy of using something that set on legs as opposed to a ground ring that covers the overall surface area of the table.

            My vise is dead flat in all directions last time I indicated it on the surface plate, so no need to tram off of it or check it on the mill.

            JL..............
            Last edited by JoeLee; 09-15-2018, 10:14 AM.

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            • #21
              I use a 10" Lathe Chuck to tram mine.

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              • #22
                Originally posted by Mcgyver View Post
                I would say that is safe conclusion....but we didn't know about the nuances, the back issue, vise being dead on etc, so you got best practices. Only you know what you work on, but for me, the solution would be a lifting device so you could take the vise off; probably 10% of the time, maybe more, I'm taking the vise off to bolt work directly to the table or use some other tooling; angle plate, V blocks, 5c fixture, RT, diving head, tilting table etc. Not having safe access to the table would really limit things.

                If the vise just can't come off, I'd be thinking of making some disk with a block that was very accurate, scraped would be my choice. The block would register to the bottom of the vise and fixed jaw and present a horizontal surface parallel and perpendicular to those surfaces to tram to. That way tram is to the fixed surfaces you believe to be true, whereas the top of the moving jaw is a bit of a variable.

                That or one of those three legged stool things.
                Thanks, and yes the info that everyone provided is good stuff, and based on the the amount of info that I provided in the 1st post was spot on. I tried to keep the 1st post brief but more detail was needed in order for anyone with many years of experience to say, yeah that will be fine based on the history of what you are using. There is quite a bit of good information that was posted and the important part that is obvious in hind site is to use the vise bed and not the top of the vise jaw to indicate off of.

                Dwight

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                • #23
                  Hi,

                  For best accuracy, always tram off the bottom of the fixture. Tram off the table if you are using the table. Tram off the bottom of the vice if you're using a vice. That way your cutter moves parallel to the surface that references the part.
                  If you think you understand what is going on, you haven't been paying attention.

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                  • #24
                    Originally posted by dalee100 View Post
                    Hi,

                    For best accuracy, always tram off the bottom of the fixture. Tram off the table if you are using the table. Tram off the bottom of the vice if you're using a vice. That way your cutter moves parallel to the surface that references the part.

                    But then do you tram with the knee locked or not?
                    Andy

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                    • #25
                      Hi,

                      Depends on what you are doing. If you aren't moving the knee, like for facing operations, lock the knee and leave it. All bets off if you unlock it. Everything will move.

                      If you are running multiple operations in one set and needing to move the knee up and down to accommodate very different tool lengths, like drill and ream, leave the knee unlocked. Might not be perfect, but it should be closer - machine wear being what it is - than locking it in two different places. YMMV
                      If you think you understand what is going on, you haven't been paying attention.

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                      • #26
                        Originally posted by Mark Rand View Post
                        I use a ventilated car brake disk. They are surprisingly flat (maybe not so surprising, since they tend to be faced with a double sided tool post). The one I got is flat to less than a tenth, and rests on the table while I sweep the indicator around.)
                        +1.
                        I use a large ball bearing, about 7" OD.

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                        • #27
                          Originally posted by Mark Rand View Post
                          I use a ventilated car brake disk. They are surprisingly flat (maybe not so surprising, since they tend to be faced with a double sided tool post). The one I got is flat to less than a tenth, and rests on the table while I sweep the indicator around.)
                          Mark, why ventilated rather than solid?

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                          • #28
                            Originally posted by tmc_31 View Post
                            Mark, why ventilated rather than solid?
                            Because ventilated ones are thicker and much stiffer than solid ones, so hopefully more stable.
                            Location- Rugby, Warwickshire. UK

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                            • #29
                              Originally posted by dalee100 View Post
                              Hi,

                              Depends on what you are doing. If you aren't moving the knee, like for facing operations, lock the knee and leave it. All bets off if you unlock it. Everything will move.

                              If you are running multiple operations in one set and needing to move the knee up and down to accommodate very different tool lengths, like drill and ream, leave the knee unlocked. Might not be perfect, but it should be closer - machine wear being what it is - than locking it in two different places. YMMV
                              All very true. But along with this should be the realization that one should keep up with the gib adjustments to minimize the change from locked to slack.
                              Chilliwack BC, Canada

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                              • #30
                                I go right over the bed, remove as many variables as possible.
                                Andy

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