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What Do You Indicate Off Of When Tramming Mill

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  • MichaelP
    replied
    Originally posted by garyhlucas View Post
    A perfect tram is when the spindle is perpedicular to the X & Y axis ways, not the vise or the table. If you are trammed perfectly to the ways the edge on a cutter will touch perfectly on the leading and trailing edges of a cut. Then you can take trim cut on your softjaws or a sacrifical plate to get the flatest possible support for your part. Of course if the ways are shaped like a banana as on my old Bridgeport then flat won’t be flat.
    How do you tram to the ways?

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  • garyhlucas
    replied
    A perfect tram is when the spindle is perpedicular to the X & Y axis ways, not the vise or the table. If you are trammed perfectly to the ways the edge on a cutter will touch perfectly on the leading and trailing edges of a cut. Then you can take trim cut on your softjaws or a sacrifical plate to get the flatest possible support for your part. Of course if the ways are shaped like a banana as on my old Bridgeport then flat won’t be flat.

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  • loose nut
    replied
    I use an old bearing (cheap/free) outer race, ground all over, since it allows me to cross over the gaps in the bed. It could be placed on blocks to elevate it up above a mill like the fixture in the pictures.

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  • vpt
    replied
    I go right over the bed, remove as many variables as possible.

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  • BCRider
    replied
    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.

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  • Mark Rand
    replied
    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.

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  • tmc_31
    replied
    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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  • thaiguzzi
    replied
    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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  • dalee100
    replied
    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

    Leave a comment:


  • vpt
    replied
    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?

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  • dalee100
    replied
    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.

    Leave a comment:


  • dmartin
    replied
    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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  • Tundra Twin Track
    replied
    I use a 10" Lathe Chuck to tram mine.

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  • JoeLee
    replied
    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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  • JoeLee
    replied
    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............

    Leave a comment:

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